News Tagged ‘Trees’

Superb Spindles.

Thursday, August 11th, 2011

In one of last months’ blogs I mentioned what a remarkably good year it is proving to be for fruit and seeds, with the warm, dry spring allowing maximum pollination, followed by a wet-ish summer when the fruits need moisture in order to swell and ripen. The Rowans – Sorbus species – undoubtedly lead the charge in mid-summer, but in terms of wow-factor, and as summer moves to it’s conclusion, the Rowans are now being eclipsed by an altogether less well-known and less celebrated group of plants – the Spindles.

Euonymus grandiflorus fruit capsules.

Spindles are from the genus Euonymus, well-known to most gardeners as the home of the very widely grown and bomb-proof (if rather innocuous) evergreen ground-cover plant E. fortunei and the equally indestructible shrubby E. japonicus, widely planted as hedging. I would guess that for many those two plants are both the beginning and the end of their experience of Euonymus, which is something of a minor tragedy, as this fascinating genus contains over 175 species, many of which are exceedingly ornamental. Spread across all of the continents (barring Antarctica, obviously!) these highly successful plants have evolved and diversified into small trees, shrubs, climbers and creepers, such as good old E. fortunei.

Euonymus planipes with semi-ripe, unopened fruit.

By far the majority of their number, however, are medium-to-large-growing shrubs. This band includes our native species, Euonymus europaeus, a deciduous shrub or small tree widespread across much of Europe and into Asia minor, and commonly seen forming part of the living tapestry of ancient hedgerows and woodlands. The wood of E. europaeus is unusually hard and was traditionally used to make the spindles used for the spinning of wool, flax and hemp, a utilitarian purpose which has lent the common name “Spindle” not just to our own species, but also to all of it’s shrubby relatives.

Euonymus cornutus var.quiquecornutus - this rare Chinese species has wonderfully "horned" fruits.

Throughout the early growing season the Spindles quietly get on with the business of growing, rarely drawing the gardeners attention. Their flowers are extremely curious and rather fascinating, but they are also absolutely tiny and are generally coloured in the green/brown regions of the colour spectrum. The casual observer might not even notice that a Spindle was flowering, even when at it’s peak. Those miniature blooms are popular with bees and hoverflies, which is always a plus in any garden, but it’s what happens next that holds the key to the Spindles splendour.

Euonymus europaeus in flower.

Following pollination the flower ovary expands considerably to form a fruit, and by mid August the fruits of the earliest of the Spindle species are beginning to ripen and burst open in the most spectacular fashion. Although their shapes vary somewhat across the species all Spindle fruits are heavily lobed, commonly likened to spinning tops or jesters hats – these are plants of great character, to be sure. Those fruits are also vividly coloured – typically bright pink or red externally, opening to reveal tangerine-orange coloured seeds. As they ripen the seeds, rather than simply being shed onto the ground, are held for several weeks  to dangle on delicate threads that extend from their cases. In a good season – and 2011 is about as good as any I can remember – the overall effect of a Spindle in full fruit is quite wonderful.

Euonymus hamiltonianus 'Winter Glory', with it's heavy clusters of fruit.

The Spindles have another trick up their woody sleeves too, and as the chills of autumn arrive the leaves of many of the deciduous species start to turn to a dazzling array of colours from deep black-ish plum-purple, through every shade of yellow, orange and red and, in some cases, bright pink, all forming a backdrop to those fruits that are often retained well into winter.

An individula fruit of E. europaeus 'Red Cascade'.

In order to produce a good fruit set two or more individuals of the same species need to be grown together. Even then some Spindles are showier than others and both fruit set and particularly autumn foliage colour will vary greatly from year to year, dependant, as they both are, on the weather. Our own native E. europaeus, one of the largest growing species, is no slouch, and bears an abundance of fuchsia-pink seed capsules, followed by bright scarlet leaf colour. The best form for use in gardens is undoubtedly ‘Red Cascade’ which couples abundant fruit set with much more reliable autumn colour. E. europaeus f. albus is a variant with porcelain white fruit capsules, and the two are particularly effective when panted together, also forming pollination partners to ensure good fruit set.

Euonymus europaeus albus.

Euonymus hamiltonianus is the next most widely grown and distributed species, and many forms have now been selected and named. The fruits ripen much later, well into autumn as a rule, and mature to pink, whilst the large, glossy leaves fade to delicate shades of apricot, yellow and coral.

E. alatus, with it's full-on autumn effect.

E. alatus is very widely grown in the USA where it is a mainstay of some municipal plantings – not exactly a recommendation, perhaps – and is also freely available to gardeners here. Plants are compact, rounded and slow-growing, forming a tangled web of branches that bear wide, corky “wings” that are pretty attractive over winter. The fruits are small and red-purple, but the autumn leaf colour is vibrant, crimson-pink.

Euonymus latifolius.

E. latifolius and E. planipes are close relatives of one another, the former from Europe, the latter native to Japan. They are both readily cultivated and each produce large scarlet fruit and brilliant autumn foliage – highly recommended.

Euonymus myrianthus.

Not all of the Spindles are deciduous, and some of the most beautiful are evergreens native to China. E. myrianthus was a species that I first encountered as a teenager and, indeed, the one that awoke my enthusiasm for the Spindles in general. That particular plant was growing, as it still does, in the National Trust garden at Killerton, here in Devon, and I spent much time being fascinated by it’s deep golden fruits as well as admiring the tropical-lushness of the long, glossy leaves. E. myrianthus is a little tender in the garden, but it’s relative E. grandiflorus, is much tougher with large leaves that can remain evergreen in mild winters, or else age to deep burgundy and are slowly shed over the winter – a great foil for the beautiful, shell-pink fruits.

Euonymus grandiflorus, with not-yet-opened seed capsules.

The recent rise in interest in the Spindles, coupled with a mass of plant-hunting expeditions to Asia, has brought many new species into British cultivation and popularised others that have long been on the horticultural back-burner.  A few of my favourites are the exceedingly elegant E. bungeanus, with delicate, arching branches, slender, drooping leaves and blush-pink fruits; the wonderfully named E. cornutus var. quinquecornutus, a narrow-leafed semi-evergreen with perhaps the most dramatic fruits of all the Spindles; and E. americanus, with fruits that look just like little pink sea-urchins.

Commonly known (in the US) as the Strawberry Bush, Euonymus americanus is irresistible in fruit.

Aside from the few somewhat tender species, the Spindles are an adaptable and easily cultivated lot. We grow them successfully here on our mildly acidic river soil, but they will thrive on most soils, and do particularly well on chalk, making them amongst the most valuable of all shrubs for those somewhat difficult alkaline gardens. They are not large or difficult to accommodate in even small sites, and provided they receive a reasonable amount of sun they will reward you year after year with their impressive displays.

The delicate autumn colours and cascading foliage of E. bungeanus


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Remarkable Rowans.

Thursday, July 14th, 2011

2011 is shaping up to be a bumper year for fruit and berries. All of the hot sun and near-drought conditions of Spring allowed the mass-pollination of flowers by feeding insects – unhindered, this year, by rain or heavy cloud – whilst the recent summer rains have promoted the swelling of the subsequent fruit to terrific proportions. Our hedgerows are filled with the glowing gold and scarlet of Viburnum berries along with the over-sized, ebony-black hips of wild roses, and will soon be heavily laden with what looks to be a bumper crop of blackberries too. Elsewhere Malus (Apples and Crab-Apples) are all developing nicely, but they have been well and truly eclipsed by their close relatives the Sorbus, or Rowans, whose giant clusters of bright orange-red fruit seem to be festooning their owners branches with unusual abundance this year.

Sorbus aucuparia - our native Rowan. A tree in full fruit can easily rival many exotic ornamentals.

Our native species of Rowan, also known as the Mountain Ash, is Sorbus aucuparia. This is one of nearly 100 species of Rowan within the Sorbus genus, Sorbus being an unusual genus in that it is sub-divided into two very distinct sections: the Rowans (Aucuparia section) and the Whitebeams (Aria section). As the common name “Moutain Ash” implies, the species is a specialist of uplands, and very often forms the final tree line at higher elevations, with twisted, wind-blasted specimens often found clinging on in the most improbable and inhospitable sites. Although entirely unrelated to the Ash (Fraxinus species) Rowans do share the pinnate arrangement of their foliage with that genus, and all Rowan species have leaves that are divided into feather-like or fern-like fingers – the pinnae.

A single Rowan leaf, divided into feather-like pinnae or leaflets, which are themselves toothed at the margins.

Rowans have adapted not just to exposure and high elevation, but also to extremely acid soil conditions, where few other woody plants would survive. Such conditions are typical of our moorlands, of course, but, aside from out-and-out alkaline chalk-lands, Rowans are perfectly adaptable and thrive in virtually all soils. This adaptability, along with their general toughness and lack of major pests and diseases has seen Rowans widely used as street trees and in parkland plantings, but in many ways they are also amongst the very finest possible trees for planting in gardens. In common with most Rowans, Sorbus aucuparia is a small tree, with a delicate airy habit. That divided foliage ensures that no Rowan casts heavy shade, which in turn makes them ideal for under-planting with smaller shrubs and herbaceous plants. The leaves of the Rowan are also inherently attractive throughout the growing season, but take on a particular appeal in autumn when they start to tint to shades of red-purple and bronze.

Sorbus cashmiriana has somewhat larger individual flowers than do most other Rowan species.

Back in Springtime the trees produce large, and very densely packed corymbs of tiny, cream-coloured flowers. The flowering display is not generally considered of great ornamental interest, although I think they do have a bumptious, fluffy appeal, but, in common with many other creamy spring flowers, they are hugely attractive to bees, hoverflies and other pollen and nectar feeding insects. Finally, then, the result of all that feverish insect attention are the magnificent berries, produced well in advance of many other trees and in full scarlet effect by August.

Sorbus aucuparia flowers.

Rowans would be well-loved and widely planted solely for the ornamental effects of those berries alone, notwithstanding all the many other attributes that the trees have to offer, but the fruits are equally esteemed by many species of birds who often flock to the trees throughout autumn. Thrushes, Redwings are Waxwings are all devotees, and many other species will also make a detour to a garden bearing a fruiting Rowan tree. We humans too have long harvested the fruit to produce Rowan jelly – a marvellous preserve with a sharp, marmalade-like flavour.

Sorbus aucuparia berries.

As already mentioned, our native Sorbus aucuparia is just one of a large number of species of Rowan, and many new species have recently been discovered, named and introduced into cultivation following recent plant-hunting expeditions to the mountainous regions of South-Western China. Our native tree is well up there amongst the best of the genus, ornamentally speaking, but almost all of the species and their ever-expanding collection of hybrids are highly attractive, incredibly easy to accommodate and exceedingly well-worth seeking out and growing.

In a good season some Sorbus can produce jaw-dropping leaf colour - this is Sorbus sargentiana in full autumn finery.

There are a few much larger growing species, most notably the magnificent Chinese Sorbus sargentiana, with it’s huge sticky over-wintering leaf-buds, and 30cm long leaves that turn to vivid scarlet in autumn. Mostly, though, the Rowans are small to medium sized at maturity, often with a rather slender, upright habit.

Sorbus sargentiana is well-known for it's over-sized, sticky winter buds.

I’m a huge fan of autumn foliage colour. Over half of our entire garden is given over to autumn colouring trees, and Sorbus certainly contains some of the worlds finest. S. commixta, is one such, with leaves that consistently turn to burnt orange and glowing red in autumn. That species is another Chinese native, as is S. hupehensis, whose leaves have a distinct blue-ish cast, before turning deep red at the seasons end, as do those of the larger-leafed S. esserteauana.

Sorbus commixta - in full autumn colour.

As with all trees, autumn foliage colour can be inconsistent and short lived, dependent, as it it, on the vagaries of our climate, and most Rowans are undoubtedly grown primarily for their display of fruit. S commixta, S. esserteauana and S. sargentiana all produce berries similar to our native Moutain Ash, but the fruit colours within the Rowans extend well beyond fire engine red. Many of the Chinese species, including S. hupehensis, as well as S. forrestii and S. koehneana, bear white berries. S. cashmiriana has the finest berries amongst the white-fruiting species, with very large, marble-like fruit held in drooping clusters that remain on the branches long after the autumn foliage has fallen.

Sorbus cashmiriana - the berries are so large that they often weigh down the branches of the tree.

The newly introduced and highly desirable Sorbus rosea has gorgeous, large, clear-pink berries whilst those of S. vilmorinii start out rose red, slowly changing to pink and finally maturing to white flushed with apple-blossom, all against a back-drop of ever-intensifying red-purple autumn foliage.

Sorbus vilmorinii.

It’s hybrid S. ‘Eastern Promise’ is similar but with larger berries that retain their deep-pink colouration throughout. Yellow-fruited Rowans are also available, including S. ‘Golden Wonder’ and the very famous, wild-collected S. ‘Joseph Rock’, which is a truly outstanding prospect when laden with it’s golden berries against a kaleidoscopic backdrop of red, orange and copper autumn foliage.

Sorbus 'Joseph Rock'.


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The forecast: Snow in March (and throughout April).

Wednesday, March 30th, 2011

Hmm…sounds improbable perhaps? But then, what are those delicate white flakes drifting and fluttering on the lightest breeze?

The answer is petals….and the original owner of those petals is the Snowy Mespilus, or Amelanchier.

One of the finest and least demanding of small trees for the garden, whose virtues I’ve already hinted at previously, as March gives way to April and the countless thousands of poised Amelanchier flower buds open, I thought it high time to give these plants centre stage for a while.

Members of the Rose family – like so many other of the finest Spring-flowering woody plants – Amelanchier is a small and rather confused genus of trees and shrubs. There are anywhere between 6 and 35 species, depending on whose definition you believe. They are all, essentially, identical in their ornamental features, and what’s more the species have interbred with abandon to the point that definitive identification of many plants is all but impossible.

One species, A. lamarckii, is a good example. Considered to be a naturalised British plant, where colonies have spread thanks to the assistance of birds, this plant is, like all but two of the Amelanchiers, a native of North America, but “our” Amelanchier is not the same as the species that grows in the USA, and could be a different species, such as A. canadensis or A. laevis, or a hybrid of one or more of these species, or a hybrid with one of the indigenous Euro-Asian species. The truth is that the differences between all of the species are so small, and variable, that the best anyone can say is that an individual plant is closest to, say A. lamarckii…well, maybe.

Amelanchier x grandiflora 'Ballerina'.

But enough of that confusion, let’s focus instead on the many good points of these delightful trees. Their common names give a few hints of their attractions and also the considerable importance that the plants played in the lives of Native American and European settlers alike. Snowy Mespilus, as already noted, refers to the wonderful blizzard of innumerable tiny petals that grace the trees and then the ground beneath the trees as Spring progresses. “Mespilus” are the Medlars, further members of the Rose family, and ones to which the Amelachiers bore a resemblance in the eyes of the first Europeans to document the new North American flora. The names “shadbush”,” shadwood” or “shadblow” are also references to the flowering season, which coincides with the arrival of the Shad – a fish that formed a staple food for many of those same early settlers.

The flowers are only one of the appeals of the Amelanchiers, however and “serviceberry” and “juneberry” are further much-used common names. These, of course, refer to the fruit – a red-purple berry that eventually matures to black which was considered to resemble the berries of the wild European Service Tree – Sorbus domestica. The fruit are edible, and in the best varieties, quite delicious, which characteristic gives rise to yet more common names including “sugarplum”,”wild-plum”, and “Indian pear”, again, all hinting at the importance of the plant in the lives of the early populations of  North America.

The fully ripe fruit of Amelanchier alnifolia.

To the Cree Native Americans the plant was “misâskwatômina”, a name that was Europeanised into “saskatoon”, after which the town of Saskatoon, Saskatchewan, was named. Finally, while we’re talking names here, Amelanchier itself is derived from “amalenquièr” the Provençal name for the European species: Amelanchier ovalis, and, despite some sources that might state otherwise, the name is pronounced:  amma-LANK-ee-er, with a hard “K” sound, which perhaps becomes more obvious when seen against it’s French language counterpart.

Amelanchier x grandiflora 'Robin Hill'.

Amelanchiers produce an abundance of flowers from a very young age, and even the tiniest specimen will pop out a handful of blooms. Within a few years all of the branches of that plant will be fully laden with blossom each Spring. Once opened the flowers are joined by the new foliage which is often flushed with bronze or copper, making for a magnificent contrast and highlighting those dazzling white flowers all the more.

Amelanchier lamarckii with deep red/bronze new foliage.

So we have a tremendous Spring display followed by branches smothered by small, but highly decorative, edible fruit, but these trees have one final trick up their sleeves as the foliage can turn to glorious shades of orange and red in a good, crisp Autumn.  Amelanchiers display their autumn finery with great gusto and reliability in North America, although the colour can be patchy of even absent here in the UK, but that is entirely to do with our erratic, maritime climate rather than any failing on the part of the plants.

Virtually all Amelanchiers are capable of producing fiery autumn foliage under the right conditions.

Despite the presence of numerous selections in cultivation – the RHS Plantfinder currently lists 44 named forms – Amelanchiers are a pretty homogeneous lot, and really there is very little to choose between them. A. x grandiflora ‘Ballerina’ was selected for it’s larger flowers and is now very widely distributed. It’s a lovely plant, but we have it growing amidst 10 or so other named forms, and frankly I’m hard pushed to tell them apart from one another.  There are a few genuinely different selections however. The lovely pale-pink flowered form A. x grandiflora ‘Rubescens’, and pink-fading-to-white-flowered ‘Robin Hill’; the slender, upright growing A. alnifolia ‘Obelisk’ & similar A. canadensis ‘Rainbow Pillar’ and the much smaller growing A. rotundifolia ‘Helvetia’ and equally compact species A. stolonifera are all distinctive.

Amelanchier 'Obelisk' - not exactly fastigiate, but the closest to an upright form the genus has to offer.

Aside from these last two, all Amelanchiers are vigorous, as well as undemanding and easy to grow in many garden situations. Depending on how they are treated and grew as young plants they can form graceful, slender trees or multi-stemmed, more-or-less globular large shrubs. The plants can eventually get quite substantial, but they retain an airy, light quality to them and the slender leaves don’t cast a great deal of shade, even in mid summer. Plants may also be pruned after flowering to retain a desired shape or keep them to a fixed size. Amelachier are tolerant of a wide range of soils, including heavy clay and even water-logging, although young plants should be mound-planted if soil is permanently wet to allow the roots to find their own way through rather than simply plunged into a soggy hole.

Amelanchier canadensis in full autumn colour in the UK.

All parts of the plants are edible and are evidently quite appealing to a variety of browsing animals, from harmless leaf-cutter bees through to more potentially damaging rabbits and deer, so young Amelanchiers should be given some protection where appropriate. They are generally very healthy plants too, although they can suffer from fungal leaf spot, particularly if grown in sheltered areas with limited air movement. Treatment of the newly emerging foliage, together with collection of fallen leaves in autumn will keep this problem in check should it appear, and an opening up of the canopy of more congested plants will help prevent it’s re-occurrence.

Amelanchier stolonifera - the smallest growing of the species.

If sheer flower power in early to mid Spring is your thing, then, whichever form, species, or selection you choose, you won’t find a better small tree than the Snowy Mespilus, and adding one to your garden will ensure that you’ll always have at least a little of the right kind of snow, right where you want it every March and April.


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Heralds of Spring: New Foliage.

Monday, February 28th, 2011

Think Spring, and think of Daffodils and their blazes of yellow, Crocuses in their multi-coloured liveries, and a galaxy of other flowers that quite literally brighten the season. But I’d like to invite you to look outside the flower box, as it were, and focus on the some of the unsung heroes of Spring. Gaze around the landscape or garden as the tree-sap rises and the warming weather ushers in the season, and the principle plant display you’ll be viewing is not created by flowers at all, but rather by foliage.

Aesculus wilsonii.

The weather may be wildly erratic but the newly unfolding and emergent foliage of plants, big and small, is the one sure sign of the arrival of Spring. There’s a lush, fresh, vivid green-ness to foliage that can be enjoyed at this time of the year, and it’s is pretty much unique to the season too. The story doesn’t quite end there though, because green isn’t the only hue on display amongst the new leaves. A fairly substantial band of plants add to the seasonal interest by producing new leaves flushed with other colours. Most typically these are shades of red, but sometimes bronze, copper, purple-blacks and, in a few cases, even near-white can be seen.

Epimedium x versicolor 'Sulphureum'.

Some of these Spring foliage effects are subtle and muted whilst others can be every bit as flamboyant and startling as the most vivid floral displays, but in all cases there’s a sound evolutionary advantage that lies behind the colours. New leaves are obviously pretty crucial to the ongoing success of any plant, and they also contain an unusually large quantity of sugars and nutrients that make a highly tempting target for browsing insects, birds and mammals.

Acer palmatum 'Orido Nishiki'.

It’s in the interests of any plant to protect this valuable investment in it’s future and they are often able to do so by loading their new leaves with doses of toxins that are intended to dissuade would-be predators from munching on their hard-won resources. To advertise this fact the leaves are coloured, and, being a more-or-less universally recognised warning colour throughout the animal kingdom, red is the primary colour of choice.

Acer palmatum 'Corallinum'.

The toxic warning effect seems to work remarkably well too. A goodly number of the trees, shrubs and herbaceous plants in our garden here in North Devon were planted, at least in part, for their Spring foliage effects, and very few of them are ever subjected to attack in the way that some of their entirely green-leafed neighbours are.

The pigment serves another, equally important function too. Many of the spring colours, and particularly those displayed by trees, are generated by anthocyanins, the same chemicals that are responsible for the red and orange leaf colours of autumn. These function as a kind of sun-screen, and are particularly important for protecting the tender new foliage from damage by ultra-violet rays.

The colour effect dissipates as the plants produce and circulate chlorophyll to their new leaves. The production of chlorophyll is itself triggered by increasing levels of light and warmth. If those newly emerged leaves coincide with a cold snap or even just extensive cloud cover, then the greening will be stalled and foliage will remain red for an extended period. So the spring foliage effect is every bit as variable as it’s autumn equivalent, and for many of the same reasons too. In addition some plants take far longer to produce chlorophyll than do others, the effect lasting just a few weeks for some, whilst extending over the entire season in others. In either case by the time it has greened the foliage will have toughened up and the need for all-out protection will have lessened.

Toona sinensis 'Flamingo'.

The variety of plants that create this spring display is extremely wide. The new foliage of the vast majority of deciduous, hardwood trees flush red to some extent, but some really go all out and are worth planting and growing for this reason alone. Good examples include Acer (the Maples) and Aesculus (the Horse-Chestnuts), both of which genera contain an array of varieties that excel in the field of bright new foliage.

Aesculus x neglecta 'Erythroblastos'.

In fact there’s an entire subsection of Japanese Maples (collectively Acer palmatum, japonicum and shirasawanum) that have been developed in cultivation specifically for their “Spring effect”, which ranges from the glowing tangerine and lemon combinations of A. palmatum ‘Orange Dream’ through to the fire engine red of the likes of A. palmatum ‘Corallinum”. Other Acers, such as the aptly named Acer pseudoplatanus ‘Brilliantissimum, open to cream and pink’ and still others to bronze, whilst a few, such as A. buergarianum ‘Nusitoriyama’, start the season with leaves of ghostly white. Quite the rainbow of colours from a group of plants normally only associated with their autumn foliage.

Acer palmatum 'Orange Dream'.

Aesculus boasts a much smaller number of species, but almost all of them look pretty impressive in Spring. A. wilsonii opens bright red, quickly turning to chocolate bronze, for instance, whilst A. x neglecta ‘Erythroblastos’ dazzles in bright shrimp pink. The same colour appears even more dramatically in the almost garish new foliage of Toona sinensis ‘Flamingo’. One of my favourites though is a Lime, Tilia henryana, whose furry, heavily toothed leaves open a silvery colour before flushing with plum purple, a colour they maintain until the end of Spring.

Pieris 'Forest Flame'.

Some of the best known and widely grown of all ornamental shrubs are grown principally for their spring foliage too – think of Pieris ‘Forest Flame’ & Photinia ‘Red Robin’, for instance. There are hundreds of other shrubby examples, but I’ll mention just one. Less well known, and a tad less showy perhaps, is the nevertheless extremely beautiful Neolitsea sericea, a relative of the Laurels whose new foliage opens a soft copper/fawn, with the texture of suede on the upper surface and of silk beneath.

Neolitsea sericea.

Things are every bit as colourful at ground level too. A quick glance around the garden this morning shows new leaves of maroon Paeonia, plum, bronze and crimson Epimedium, golden yellow Aquilegia, silver to near black Ranunculus, a whole array of metallic colours amongst the ferns, and the breathtaking bronze and silver marbled foliage of Podophyllums (to name just a very few) all about to burst into view.

A Podophyllum delavayi hybrid.

Spring delivers so much garden colour and variety to explore and play with, and that’s all before you even think about flowers…


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The Winter Garden: Pruning

Monday, February 14th, 2011

Many gardeners who are otherwise reasonably confident in their approach to the care of their plants become less sure of themselves when wielding a pruning saw.

Two approaches that I’ve regularly come across are :  a) ruthlessly cut everything back or:  b) do nothing. Ever. There is also a common misconception that pruning is a kind of “dark art” best left to professionals, and/or a belief that every single plant has it’s own required pruning regime, but really neither are the case, and a few simple rules will suffice for most of your woody garden inhabitants.

The other oft-seen idea is that trees and shrubs always need to be pruned on an annual basis. The most frequent outcome of this approach is that spring flowering trees and shrubs never actually flower or set fruit in such gardens, because, of course, all their lovely dormant flower buds were merrily chopped off in the name of tidying-up the plant.

Winter allows a much clearer view of the arrangement of branches.

Pruning-wise you can divide pretty much all of your flowering trees and shrubs into three categories:

1. Spring flowering, which, as in the example above, always means that flower buds are set on the previous years wood. Such plants should only be pruned immediately after flowering, allowing them the remainder of the growing season to set the buds for the next years’ flowers.

2. Summer/Autumn flowering, which generate their flower buds on new wood that is created through the course of the same growing season. These plants should be pruned in winter.

3. Tender plants, which, regardless of their flowering season, should only ever be pruned when they are in full growth and all danger of frost has passed. Earlier pruning of such plants will often encourage widespread dieback and/or trigger growth too early in the year.

In addition, Winter is the preferred time of pruning for many trees because cut branches will not bleed sap whilst they are dormant, plus the bare leafless branches allow better access to and visibility of the branches. Still, whatever the time of year, the first consideration though is why prune at all?

It’s worth bearing in mind that woody plants do not prune themselves when growing in the wild, so there is no inherent need to prune from the plants’ perspective. For the gardener, though, there are some definite benefits. Before looking at shape and size the first consideration should always be to look for and then remove any dead, diseased or damaged branches.

Wood that is dead but still attached to a tree or shrub is a prime reservoir for infection – bacterial and fungal – that can easily spread into the healthy tissue of the plant. Likewise branches already showing the effects of disease threaten the health, or even the survival of the whole plant. Bacterial canker is common, particularly on fruit trees, and an array of fungi are all too ready to set up home too.

Coral Spot - a very common fungal disease of dead branches.

Dead and diseased branches should be taken back into clean, healthy wood. On shrubs this means cutting to just above a pair of growth buds, whilst tree branches should be taken back to live wood or removed entirely back to the trunk, depending on the shape and symmetry of the plant.

Cutting back to just above a pair of live buds.

Shrubs and trees are also subject to damage over winter. The last two UK winters, in particular, have brought extremes of cold and snowfall, both of which can cause severe damage. The weight of snow and/or ice can easily cause branches to shatter and tear, leaving large open wounds, whilst severe cold on it’s own can produce bark split as the sap freezes and expands.

Major wounds are also major sources of infection, and, as before, branches should be cut back cleanly into healthy wood, thus reducing the surface area for infection and preventing necrosis from taking hold in the damaged tissue.

When taking branches back to the trunk it’s important not to leave snags and stubs. These stubs will inevitably die back, potentially infecting the main trunk. It’s even more critical not to cut into the trunk itself. Trees have a natural infection barrier that is centred on their trunk and main branches, and, where possible, they will act to isolate dying material and reduce the potential for infection… so long as that barrier is not itself damaged by poor pruning!

Cutting back to the trunk using a pruning saw.

Large branches should be handled with great care and some forethought. Their weight can easily lead to them tearing away in mid-prune, ripping the bark and causing further wounding. Such branches should be cut first on the lower side, to relieve the weight pressure, with the cut being finished off from above. It can also be handy to have a trusty helper on hand to support the weight of branches to prevent tearing and allow a clean cut.

Having dealt with the sickly, damaged wood you can then consider shaping and sizing. Again, most plants don’t need to be cut back, but they may have outgrown their position, or require attention to restore balance and create a more pleasing shape.

Young trees, in particular, can benefit from some formative pruning to encourage the development of a strong leader, or to remove twiggy side shoots, particularly in instances where you’re seeking to create a handsome, clean trunk  once the tree has grown to maturity.

Formative pruning to open up the trunk of a young tree.

Another good reason for pruning is to promote a flush of growth once Spring arrives. This is the ideal way to restore vigour to tired looking shrubs whose flowering has started to wane. Many garden shrubs end up flowering at their uppermost points only. This may be where the most light and pollinating insects will be found – which are the reasons the plant is flowering in the first place – but when such flowers are pretty much out of reach then the time for action has arrived. Consider how much growth the plant is likely to put on each season and the level at which you would ideally like to have the flowers and the “bulk” of the plant, then shape accordingly.

Many entire books have been written about pruning, so this is a necessarily brief run-through of the subject, but before you reach for those loppers, secateurs or saw there are another couple of important issues to consider. Firstly, tools. It’s no good trying to tackle a tree branch with a pair of secateurs, nor a whippy shrub with a pruning saw, so make sure that you have the right tool(s) for the right plants.

Pruning Tools to tackle any eventuality.

It’s equally important to make sure those tools are sharp or you risk creating jagged surfaces and torn bark. Finally always consider plant hygiene. If you have just removed a branch that was harbouring disease then your pruning tool will very likely be carrying the spores of that disease with it to the next healthy wood that you cut into. Disinfecting tools regularly is therefore vital. There are proprietary disinfectants that will do the job, but boiling water works equally well.

The final consideration, but again, one that need to be sorted before you begin, is on treatment of the cut surfaces. Small cuts and shrubby branches don’t require any treatment, but wounds on larger branches do need attention to minimise the potential infection.

The advice used to be to fully seal such wounds and a variety of paints and tars were (and still are) marketed for the purpose. It’s now known that this is entirely counter-productive, since a galaxy of bacterial and fungal spores are ever present in the air and are thus transferred to the cut as soon as you make it. By sealing the cut you seal these spores into the tree and actually encourage infection and discourage natural healing. Breathable balms are now the way to go and help to promote regrowth and healing whilst combating the potential for infection.

Pruning Balm.


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The Winter Garden: Rehabilitating the Conifer.

Thursday, January 20th, 2011

Picea orinetalis 'Aurea'.

Trends and fashions in garden plants wax and wane just as they do in clothes or music, and one decades “must-have” garden plant can all too quickly become the next decades “wouldn’t be seen dead growing it”. Often such plants have become victims of their own successes – so ubiquitous and widely grown that they come to represent an era in their own right.

Picea likiangensis - startling cones of red/purple.

Kniphofia – Red-Hot Pokers – and Cortaderia – Pampas Grass – are pretty good examples. Quintessential plants of the ’70′s they were both relegated to the compost heap of all “fashionable” gardens in the 90′s.  The plants themselves, of course, weren’t to blame, and, as is the way with fashion trends, both are now back in a big way, with Kniphofia, in particular, one of the hippest plants for the border all over again.

Cunninghamia lanceolata

What does any of this have to do with conifers, much less winter gardening you may be asking…well, at about the same time that front gardens were being filled with those Pampas and Pokers back gardens were being planted out with faux rockeries and dwarf conifers. Both of these fell foul of gardening fashionistas sometime later that same century and, aside from use as hedging, the use of conifers in many gardens became all but unthinkable. A situation that, for many gardeners, remains largely unchanged to this day.

Pinus bungeana - python-like flaking bark.

It’s pretty hard to consign such a huge and important group of plants to garden history, however. The problem for conifers in gardens arose not so much with the plants themselves but the way that they were used and the selections that were promoted via garden centres. The dwarf, often shapeless blobs that came to dominate so many gardens denied colour, variance and (ironically) seasonal interest to many plots and were seen as the epitome of suburban gauche, whilst mis-planted leylandii hedges just compounded the problem.

Sciadopitys verticillata.

Conifers are, of course, a numerous, diverse and fascinating group of plants. Having paid homage to giant Sequoia in California, amongst others, I can testify to their enormous appeal and often astounding beauty. These two-thousand-year-old giants are a world away from some golden dwarf perched in a dodgy rockery, but delve into the vast array of conifers now available to the gardener and you open up a treasure trove of forms, textures, scents & colours.

Athrotaxis laxifolia.

AND (finally arriving at the crux of the matter…) Winter is the season when they truly excel. No matter how many winter-flowering bulbs, shrubs and perennials you gather together nothing better gives an air of majesty, structure and sheer personality to the scene than a well chosen and well placed conifer or two. What’s more the effects of frost, snow and winter light can transform coniferous foliage into a thing of sparkling magic.

Pinus wallichiana.

I must say, however, that I still have an aversion to those blobby, often gold-leafed dwarf conifers with very finely divided foliage – Thuja, Juniperus, Platycladus are perhaps the main culprits. For me they lack the two primary joys that conifers can bring to the garden – striking bark and bold foliage. Instead I’d like to turn your attention to three key genera - Abies (the Firs) Picea (the Spruces) and Pinus (yep, the Pines).

Abies koreana - numerous blue-ish cones produced from an early age.

These are three big groups of plants that offer an array of bold leaves, beautiful bark, elegant forms and sometimes spectacular cones. A few of the species are suitably small growing for almost all gardens – the beautiful violet-coned Abies koreana and the fabulous Lacebark Pine – Pinus bungeana are two such for example – but there are also a multitude of slower, smaller, stiffly upright and weeping forms that have been selected.

Many of these offer tremendous beauty and potential for moderate or even small sized gardens. Even in limited space the addition of just one specimen conifer – say Picea omorika ‘Pendula’ – will add tremendous personality and depth to the garden in winter as well as providing a perfect backdrop for winter-flowering shrubs like Hamamelis.

Picea omorika 'Pendula' - every individual forms it's own unique shape.

Whilst these three key genera should perhaps comprise the backbone of the winter garden supporting roles could also be played by a cast of somewhat less familiar coniferous beauties, many hailing from the southern hemisphere. Cunninghamia lanceolata is a fabulous and deeply exotic-looking gem from South America with huge, spiky foliage; Athrotaxis species are small, highly architectural conifers native to Tasmania; Podocarpus salignus is an extremely graceful Chilean native with drooping, willow-like deep green foliage; Sciadopitys verticillata is a unique and extremely ancient species with tremendous personality and a fascinating appearance; Wollemia nobilis is the headline-grabbing newly discovered Australian relic that is proving to be remarkably garden hardy here in the UK.

Wollemia nobilis.

Whichever you opt for the key is to think big, and think bold. Consign the apologetic blobs to yesteryear and allow the full beauty of these magnificent plants to reign supreme in the winter garden.

Podocarpus salignus.


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The May Tree.

Monday, May 17th, 2010

Right about now hedgerows, parks, woodlands and gardens across the land are full of frothy white blossom, which is itself buzzing with a multitude of hoverflies and bees. Richly evocative of an English spring, there’s little that’s more eye catching or pleasing to all of the senses than a May Tree in full flower.

A young Hawthorn, or May Tree.

One of the most marvellous and beautiful of our native trees Crataegus mongyna – AKA Hawthorn, Whitethorn, Haegthorn, Quickthorn or May Tree – has an ancient relationship with mankind.

The old Anglo-Saxon name Haegthorn – literally the “Hedge Thorn” – as well as Quickthorn – referring to the value of the plant as a living, impenetrable barrier – shows that it has long been the most valued of hedging and boundary plants. But the Hawthorn has much more to offer than a life as a prickly hedge. These are truly multi-season trees. In good seasons the foliage turns bright red in October.

Hawthorn berries, all a-glow.

Autumn also sees them smothered in tiny bright red berries (the “Haws”). These are packed with antioxidents, vitamins and minerals and are an invaluable pre-winter food source that is harvested by anything and everything that can get to them.

As well as providing great autumn viewing interest to us those berries are a guaranteed bird magnet and they alone make a Hawthorn a near-essential element of any wildlife garden.

Actually much of the plant is edible in one way or another. As well as the fruit that are traditionally turned into jellies and jams the young leaves can be eaten as a salad vegetable, or cooked and added to soups whilst the flowers and flower buds make a pretty and tasty garnish.

Would you like Hawthorn leaves with that, Madam?

Hawthorn wood has long been used for carving, whilst the tough root wood is traditionally used for box making. The trunk wood is also unusually dense and burns at an extremely high heat, so was the wood of choice for smelting iron.

Those individually delicate pure white flowers open from tiny, pink-blushed buds and, after being pollinated, the flowers age back to pale pink before falling in a carpeting confetti shower in early June. Other forms have much deeper pink flowers and these make a pleasing landscape contrast with the white.

Not surprisingly, given it’s long association with mankind and ubiquity in the landscape Hawthorns have many magical and pagan connections, legends and tales associated with them.

Their thorny nature as well as their often somewhat gnarled, Tolkein-esque appearance saw them approached with some trepidation and considered the haunt of  faeries, elementals and assorted enchantments.

A pink, double-flowered Hawthorn.

The common name of May Tree comes from the plants role in traditional May Day celebrations, when both people and their houses were dressed with May blossom (“bringing home the May”).

The popular rhyme “Here we go gathering nuts in May” was sung by the young men, gathering not “nuts” (which are around in Autumn rather that Spring) but “knots” of May blossoms for those May Day festivities.

Those celebrations, which are still richly enjoyed across much of the country - including our Devon neck of the woods – are all about welcoming the arrival of spring, new life and new growth.

Folks “wear the green”, by decking themselves in Hawthorn greenery and flowers, whilst the appearance of the early May blossom always had great significance and itself symbolised the beginning of new life and the onset of the growing season.

Snowy white blossom.

Hawthorns are also extremely long lived. The most ancient of all trees in France is a Hawthorn, reputed to be over 1700 years old.

The oldest British specimen, known as “The Hethel Old Thorn”, grows near Norwich and is believed to be around 700 years old, whilst the most legendary is undoubtedly the famous Glastonbury Holy Thorn in the old ruined Abbey.

Possibly even better news is that Hawthorns are ridiculously easy to grow, and failure is pretty much impossible. They will grow in virtually any soil (aside from a perpetually wet one) and will cheerfully inhabit any aspect.

A single flowered pink form.

Here we have them planted everywhere from full sun to deep shade, although they certainly flower better when given a sunny aspect.

In a completely ideal and open situation they can eventually reach as much as 8 metres (25 feet) in height and breadth. Where space is more limited Hawthorns can also be severely pruned to any acceptable size and shape without compromising flowering.

So from a historical, cultural, culinary, wildlife and aesthetic point of view the Hawthorn is one very special native tree. Why not join in an ancient English tradition and find a spot to plant your own May Tree today.


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Magnificent Magnolias.

Friday, April 9th, 2010

Magnolia 'Wildcat'.

April is the month when flower power really arrives in the garden. It feels like things are springing into life almost as you watch them, with new buds opening everywhere each and every day.

It takes real floral star quality, then, to shine through all this colour, life and activity, and be crowned the undisputed (by me at least….)  ruler of the garden in April, but this month nothing can come close to touching the Magnolias.

Aside from their flowering spectacular, which I’ll come back to shortly, Magnolias have a fascinating story to tell. They are considered to be the first flowering plants ever to have evolved on this green earth. Fossils of those very early flowers date back over 100 million years and preserve records of flowers that look almost exactly the same as today’s wild Magnolia species.

Magnolia 'Felix Jury'.

What’s more, these very early proto-Magnolias evolved well before flying insects. It’s actually the arrival of their flowers that triggered an evolutionary arms race that would eventually lead insects to take to the wing so that they could more effectively reach those same flowers.

If you take a close look into any Magnolia flower today you’ll most likely find a seething mass of tiny, pin-head sized pollen beetles, and it’s actually these little guys who today, as 100 million years ago, serve as the plants’ principal pollinators. All beetle-pollinated flowers share a few common characteristics – very large, simple flowers coloured white pink or red with masses of pollen and virtually no nectar.

Magnolia 'Judy Zuk'.

Nectar arrived later, in more highly evolved flowers where it serves to attract the likes of butterflies, moths, bees and eventually bats and birds to serve as pollinators. Magnolias do, in fact, exude a nectar-like substance in small quantities, although it’s function is to capture pollen from passing beetles (to improve pollination chances) rather than to feed flying insects.

There are well over 100 species of Magnolia currently recognised and many more hundreds of cultivars and hybrids, but until very recently here in Britain you’d be very lucky to see more than three or four of these anywhere outside of large specialist gardens and collections.

Magnolia 'Atlas'.

M. x soulangeana is the rose purple and white bicolour-flowered plant (eventually a medium/large tree) that is so widely planted here in the UK, including as a street tree. M. stellata is the smaller Star Magnolia, usually grown in pure white forms, whilst M. grandiflora is the North American evergreen species in which the best forms have large, felted leaves, and which is often seen planted against the walls of stately homes. M. x loebneri is the fourth, though less commonly planted Magnolia, producing huge numbers of strappy flowers of white or pink.

For the last 50 years or so handfuls of dedicated breeders have been working on improving the selection of Magnolias available for the garden. Some of the aims were to improve hardiness by pushing back flowering time (thus avoiding the earliest frosts) widen the selection of sizes, colours and perfumes and attempt to create smaller Magnolias better able to fit the average garden.

Magnolia 'Daybreak'.

There are a huge range of wild species to draw from, but developing new Magnolias is a painfully slow business that also requires huge amounts of space so that new crosses can be grown on to flowering age – we’re talking decades rather than seasons. Still, now there really is a kaleidoscope of colours and forms of these majestic plants out there just waiting to be planted.

Although three of those widely grown varieties are still very much worthy of any gardeners attention, the ubiquitous hybrid M. x soulangeana has been completely surpassed and superseded as a garden plant.

Magnolia 'Sweet Merlot'.

The magnificent giant Himalayan tree species (all very slow maturing and early flowering and hence pretty frustrating outside of very large, sheltered, southern gardens) have been crossed with later flowering and smaller growing species and hybrids, bringing intense violets like ‘Black Tulip’, ‘Sweet Merlot’ & ‘Old Port’,  near reds – ‘Felix Jury’ is one of the best yet – a wide range of true pinks including  ’Daybreak’, ”Star Wars’, ‘Apollo’ & ‘Spectrum’, and many large flowered bi coloured & whites like ‘Athene’, ‘Sayonara’ and the truly giant flowered ‘Atlas’.

Magnolia 'Eva Maria'.

The very late, American yellow flowered M. acuminata has been crossed with everything possible, creating a very exciting, extremely hardy range late flowered hybrids.

Colours range through pinks – ‘Daybreak’ (which is also regarded as the finest of all Magnolias for fragrance) ‘Pink Royalty’, ‘Rose Marie’, ”Coral Lake’, ‘Denis Ledvina’, ‘Blushing Belle’, ‘Phil’s Masterpiece’ – creams – ‘Ivory Chalice’, ‘Yellow Lantern’, ‘Gold Cup’ – yellows -’Daphne’, ‘Yellow Bird’, ‘Limelight’, ‘Lois’, ‘Judy Zuk’ – and even peach – ‘Peachy’, ‘Eva Maria’, ‘Amber’, ‘Apricot Brandy’.

Magnolia 'Goldstar'.

Finally, the smaller M. stellata (itself one of the parents of M. x loebneri) has been successfully crossed and backcrossed to widen the range of smaller Magnolias. The yellow/cream flowered ‘Goldstar’ is a real favourite, as are the semi-doubled ‘Wildcat’ & ‘Powder Puff’ and the beautifully formed, pure white ‘Donna’.

Once it’s been planted (and well tended of course) a Magnolia will grow to form a very substantial garden feature for generations to come, so it’s got to be worth taking the time to seek out and plant one of the superior forms that are now available. In gardening terms the reward, each spring, will be almost unparalleled.


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Trees for the garden.

Monday, February 15th, 2010

Stewartia - one of the finest of all garden-sized trees.

As night follows day, having blogged about how to plant a tree in my last post it seems pretty logical to follow with some suggestions as to which trees to plant.

Most gardeners obviously don’t have rolling acres to play with, and at best might only be able to make room for a couple of small to medium trees in their garden, so it’s pretty essential that any tree has to really deliver to earn it’s place. With this in mind I’ve been ruthless with my selections and have only included small-ish trees that offer multi-season interest. Aside from the beauty and appeal inherent in any tree, many can also offer various combinations of ornamental bark, flowers, foliage, fragrance, fruit, and autumn colour, as well as being appealing to wildlife, so I’ve gone for recommendations that tick as many of these boxes as possible.

Cornus kousa - tasty fruit.

I mentioned Cornus kousa – the Japanese Dogwood – a few blogs ago, and I’m going to start with this beauty here too.

Moderately sized, even at maturity, and easy to please in all but the harshest environments this supremely elegant plant definitely has a prolonged appeal.

Showy floral bracts of white, pink and cherry red slowly enlarge throughout May and June, to be followed by equally ornamental, edible, large, strawberry-like fruit in early autumn.

The show culminates with vivid displays of leaf colour in October. Lots of selections are available, but the deep pink flowered ‘Satomi’ is pretty tough to beat.

Amelanchier - autumn finery.

Flowering earlier in the Spring the Amelachiers are slender, graceful members of the rose family. There are a number of species, many of which are essentially shrubs, but A. x grandiflora is more definitely tree-like.

Commonly known as the Snowy Mespilus, throughout April the trees are smothered by delicate white or pink blooms which contrast with the new foliage that unfurls a bronze-red colour.

Sweet, purple-black blueberry-like fruits are formed in autumn and these are highly edible to humans and birds alike.

If all that wasn’t reason enough to plant one, many Amelachiers, such as A. grandiflora ‘Autumn Brilliance’, also have red, orange and gold autumn leaf colour.

Abies koreana cones.

For something completely different how about Abies koreana, the Korean fir, an easily accommodated, slow-growing conifer with a typically Christmas Tree shape.

The foliage is bi-coloured, with each needle dark green on its upper surface and bright silver beneath.

Attractive at any season this little guy really comes into his/her own when the cones start to appear – which they do on even the smallest specimens.

These are blue-violet, covered with a silvery white bloom and are held upright, looking like candles all along the branches. Just beautiful.

Arbutus x andrachnoides - the polished trunk glowing after rain.

Another evergreen, though not, this time a conifer, Arbutus x andrachnoides is a hybrid form of the Strawberry tree.

One of my very favourite plants, this has handsome, glossy, lightly serrated foliage all year round, with clusters of little white urn-shaped flowers appearing in spring, and often again in late autumn and winter.

Some of these go on to form the bright-red fruit that do indeed resemble wild strawberries, but actually the real glory of the tree lies elsewhere.

As the plants mature they form very appealing, sinuous, twisting branches, covered with papery, deep red bark which flakes away to reveal a gorgeous, deep red glossy trunk – spectacular after rainfall.

Another tree renowned for it’s bark is Prunus serrula – the Tibetan Cherry. This well known little beauty has a satin-like trunk that resembles highly polished mahogany. Although it’s far from the showiest cherry in term of its flowers or fruit, spring does see the tree transformed with a dusting of pure white blossom, plus the small, bright scarlet fruit are attractive to birds in autumn.

Malus tschonoskii - a crab-apple for all seasons.

Malus is a large genus that includes the apples and crab-apples. Many of them are well worth growing, and the best combine showy flowers and fruit with fine autumn colour.

My favourite three are the stiffly upright-growing M. tschonoskii – the Pillar Apple – with open, white flowers, red-tinted crab fruit and startling autumn colour; M. transitora, which never fails to amaze me every year with it’s super-abundance of flowers and the little orange-yellow fruit that follow, before the whole tree turns to shades of apricot in Autumn; and M. baccata, the Siberian Crab, with deliciously fragrant white flowers, equally delicious deep red fruit and, in a good year, bright red autumn foliage too.

Cercis siliquastrum.

Cercis canadensis ‘Forest Pansy’ is an extremely widely grown small tree with deep purple-red heart-shaped foliage.

The species is very showy in flower in its native North America, but the British climate doesn’t quite suit it and it rarely puts on much of a show here.

I much prefer its Asian relative, C. siliquastrum – the Judas Tree. This has equally beautiful, rounded foliage but is also smothered with purple-pink flowers (there’s also an even more beautiful pure white-flowered form) in early summer, followed by elongated, bean-like seed pods that mature to an ornamental deep red.

Parrotia persica - unrivalled in autumn.

It often amazes people that a tree whose native home is Iran should do so well in overcast Britain, but Parrotia persica comes from the Alborz mountains in the far north of country, which are actually home to lush, cool upland forests.

Parrotias are well know for spectacular autumn tints, when they turn into multicoloured arrangements of purple, gold, orange and red, but the trees also have patterned, bark that flakes away in small sheets to reveal the pinky-yellow colour beneath.

A final surprise comes in the dead of winter, when petal-less deep red flowers erupt straight out of the bare stems, eventually falling to form a ruby red carpet beneath the trees.

Styrax obassia.

A real garden aristocrat, Styrax obassia almost didn’t qualify for inclusion on this list, since it can’t boast any dramatic fruit, bark or autumn foliage finery.

What is does have, though, are large racemes of beautifully fragrant, pure white bell-shaped flowers that resemble large bunches of snowdrops. These are, rather usefully, produced in summer when few other trees are doing their thing.

The other thing I love about this tree is the foliage; Pure green, almost circular, and around 20cm across, each leaf resembles a small dinner plate with a little drip-tip added on one side.

Sorbus vilmorinii - a real wildlife magnet.

Like Malus, Sorbus is another big genus of trees and shrubs, some of which are amongst the most ornamental of all garden plants.

Separated into the “Whitebeams” with large, entire leaves, and the “Rowans” with heavily divided, fern-like foliage, most of the best for garden use come from the second group. Our own native Rowan M. aucuparia is a highly attractive small tree, very appealing to insects when in flower, and to birds when laden with bright red autumn fruit. M. commixta ‘Embley’ is it’s Japanese counterpart, and adds bright scarlet autumn leaf colour to the mix. The Chinese S. vilmorinii is perhaps the pick of them all, with exceptionally fine, very heavily divided foliage that colours well in autumn and large clusters of fruit that change from pink to violet, eventually ageing to white

Stewartia psudocamellia - large flowers and bright autumn colour are seasonal, but the flaking, peeling trunks are attractive year round.

I have, arguably, saved the best to last. Rarely seen outside of specialist collections I truly believe Stewartias to be the finest of all garden trees. Close relatives of the camellias these beauties leave no ornamental stone unturned.

S. sinensis, S. rostrata, and the more frequently seen S. pseudocamellia are the three that do best in British cultivation. They all have the most gorgeous peeling, flaking, and eventually polished trunks that look like the body of some giant python, coupled with large, creamy white, camellia-like flowers, and stunning purple red and orange autumn colour.

Give them a sheltered spot in the garden, ideally in semi-shade, and they will reward you with a lifetime of year-round beauty.


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Planting trees (and shrubs too…).

Friday, February 12th, 2010

An old gardening book of mine quotes the owner of a large country estate (one which boasts an impressive collection of rare trees) as saying that he paid: “a shilling for the tree and a pound for the hole,” the pound being the cost of the labour involved to dig a sufficient hole. This quote has always stuck with me, and generally runs through my mind pretty much every time I plant anything larger than a bulb.

Prunus incisa - a pretty flowering cherry that makes an ideal garden tree.

The simple fact is that, once planted, trees and larger shrubs will likely never be moved, and, if all goes well, will remain in place for decades or even centuries to come. Aside from mulching, the only chance that you will ever have to improve the structure of the ground where they will grow is at the time of planting. Bearing that in mind it has to be well worthwhile putting in the time and effort to ensure your spindly sapling will one day grow into a mighty tree (or shrub…)

Although it’s possible, with care, to plant at any time of the year, by far the best seasons are  late autumn and the early spring, when the plants will be dormant and will suffer far less shock than they would in the growing season. The ideal weather is cloudy, cool, windless and most definitely frost-free, so if necessary delay planting until suitable conditions occur.

It was long thought by many that the most important factor in tree planting was the fertilisation of the ground, with the addition of composts, manures and so on. Research has now shown this to be not the case; in fact the fertilisation of your planting hole is actually likely to prove harmful, or even fatal to new trees, the emphasis instead is all on the preparation of the hole itself.

Planting hole preparation - the most important job of all.

Generally speaking the bigger the planting hole the better. The aim is to break up as large an area of soil as possible, not in terms of depth, but rather width, because it’s here that your tree will be making it’s initial forays into it’s new soil.

How big is big? Certainly the planting hole should be considerably larger than the root ball of your new tree and none of the roots should have to be bent or curled to fit in.

It’s important to plant on the same day as you dig the hole as exposure to the elements will kill off many of the beneficial micro-organisms, and in particular the fungi that are present in the soil. Microrrhizal fungi are amongst the most essential members of the subterranean community as far as plants are concerned, and most trees actually derive much of their nutrition not directly from the soil, but rather from these fungi with whom they set up a symbiotic relationship.

Mound planting - to help trees establish on wet ground.

It’s often necessary to be a bit flexible with your planting location too. If you dig down and find standing water or a layer of bedrock, for instance then it’s best to stop right there and consider a new spot.

Having said that trees can be planted in wet sites by mounding soil up above ground level. We’ve taken this approach is a seasonally wet patch of our garden where we have succeeded in establishing a number of Acer palmatum by planting each one on a large mound as much as 60cm above the natural ground level.

In very dry locations you can take the opposite approach and plant in a dip so that any rain-water that happens by will be diverted to the roots of your tree. Be very, very wary, though, of creating a sump that collects water all year round, roots need oxygen as well as water so this is a quick recipe for a drowned plant.

Staking - short and sweet.

Before reaching for the tree, the next step is to consider staking. Unless your new arrival is on the short and stocky side then it’s often necessary to secure by tying to a stake. This makes sure then tree isn’t rocked – or even uprooted – in the wind and will allow it to properly establish at the roots.

Stakes should be short but sturdy – always thicker than the tree itself. It doesn’t matter if the top of the tree moves around (within reason), in fact it promotes thickening of the trunk, and if you stake too high you will end up with a perpetually spindly trunk that may never be able to support itself.

Securely drive the stake into the planting hole on the side of the prevailing wind and make sure you have a good, durable tie to hand – preferably rubber or plastic to minimise rubbing – and long enough to secure the tree but still allow for some movement and flexing, again to encourage strengthening of the trunk.

A rootbound pot-grown tree.

Once the hole is prepared you can unwrap or un-pot your tree or shrub and take a good look at its root system. My experience of planting many thousands of trees and shrubs is that unless the roots are relatively free and open then establishment will be delayed, often for several years. This is particularly key if your tree has been pot-grown.

If the roots are looking bound-together and have spiralled around the inside of the pot, and a gentle shaking and teasing won’t budge them, then the best remedy is to soak or hose away some (or even most) of the compost to try to free the roots without breaking them.

Next mound up a small amount of the top soil that you’ve previously removed into the centre of the planting hole until the tree sits with the base of it’s stem/trunk at the natural surrounding ground level. This level is really crucial. If you plant too deep, with the trunk collar under ground level, then the bark at the base of the tree will almost certainly rot off and the tree will be killed. Too high and the roots will be exposed, severely weakening, and probably destabilising the whole plant.

Then, breaking up all large clumps of soil that you’ve dug out, and crumbling everything into as fine a tilth as possible (again to allow quick and easy root penetration) quickly infill the rest of the planting hole and gently press in with your hands – not with a big stomping, root and air crushing boot! – then water thoroughly to let the soil settle into the hole.

The only material that goes back into the planting hole should be that which came out – or if it’s very poor or stony, other topsoil from as near as possible to the planting hole.

Why not take the opportunity to add lots of juicy well rotted manure or compost to feed the tree? The breaking down of this type of material completely changes the soil chemistry near the tree roots. It robs the soil of oxygen for it’s own decomposition, kills most of the beneficial, but very delicate fungi, and creates excess moisture that leads to root rot. Fertilisers also promote excess shoot and leaf growth, but do nothing for the root system, and will leave the tree with a desperate imbalance that may result in massive die-back as time passes.

Betula nigra - the river birch: well mulched, grass-free and thriving.

Finally it’s important to protect the new tree from competition for water from weeds, and particularly grass – vital if planting in a lawn or field. So once safely planted and staked the planting hole should then be mulched.

We use purpose made mulch mats, which fit flat over the planting hole and give years of protection as they slowly decompose. Well composted bark or garden compost is another, and more attractive alternative for the garden, but be sure to leave the trunk itself mulch-free or you’ll invite basal bark rot once again.

All that then remains is to keep well watered during dry spells, particularly for the first few years, and top up with an annual mulch. Then, sit back and enjoy the fruits of your one-days-labour for many, many years to come.


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