News Tagged ‘Winter Gardening’

Hooray for hellebores.

Friday, March 19th, 2010

Some of the colours of the hellebore rainbow.

There’s no doubt that hellebores are pretty special garden plants.

Flowering at the tail end of winter, with only snowdrops and the occasional early Iris, Cyclamen and Crocus for company, these improbable members of the buttercup family never fail to inspire as they push up their multicoloured flowers and divided leaves through snow or ice, or whatever the winter weather has to throw at them.

Emerging so much earlier than most other spring-flowering plants hellebores would probably command attention even if they were small and weakly coloured.

Apricot with dark nectaries.

Thanks to generations of dedicated enthusiasts, there’s not much chance of that, and these perennials now pack a truly dramatic punch with large cup-shaped flowers in a kaleidoscope of colours from vivid green and pure white through yellow to apricot, pinks & purples and on to the most intense slate blues and deepest violet blacks.

Flower shapes vary from very rounded and cup shaped, to starry with a range of different shaped doubles. Some also have dark red or black-ish nectaries, which gives a different look altogether.

As if that range weren’t enough the flowers of many forms also come with a multitude of different markings. These have evolved to guide pollinating insects safely and accurately towards the reproductive organs of the flowers, but luckily for us it’s not just the eyes of passing bees that are dazzled by the endless different combinations of spots, blotches and lines.

A bit of Botany.

Near black - both flowers and foliage.

Before going any further I need to qualify exactly which hellebores I’m referring to. Helleborus is a small genus of around 15 species, all but one of which are native to Europe. H. foetidus (the rather unkindly named Stinking Hellebore) is actually a British native, but the large majority hail from central southern and eastern Europe, with particular strongholds in scrubby mountainous regions of the Balkans.

The only non-European species is the beautiful H. thibetanus, which, you won’t be surprised to hear, is a native of Tibet.

H. niger (the so-called Christmas Rose) and H. argutifolius are both very well known garden plants, but the large-flowered, multi-coloured garden hellebores are all very complex, multi-species hybrids based in part of the species H. orientalis.

Double white spotted.

Strictly speaking these should be called H. x  hybridus, but in reality hardly anyone used this name.

As a group the plants have widely and pretty consistently come to be known as the Orientalis Hybrids (as well as picking up the unfortunate and totally misleading moniker Lenten Rose)….having said that for simplicities sake I’m going to continue referring to them here simply as hellebores.

Cultivation.

Reverse picotee white spotted.

One of the other great appeals of hellebores is that they really are incredibly easy, tolerant and rewarding plants to grow.

In their wild habitats the species invariably live on slightly alkaline, rocky and generally pretty impoverished soils.

In cultivation they will happily grow in virtually anything you care to give them, although they will of course grow better and certainly provide a better flowering display if they have something halfway decent to sink their roots into.

Hellebores are essentially plants of open, light woodland, so a good, organic-rich soil with a free draining structure will give optimum results. They are also partial to a good feed, and though far from essential, a heavy mulch with well rotted manure in late autumn will see the plants respond with extra lush and large growth the following spring.

Green streaked picotee.

Despite their woodland origins hellebores are actually very sun tolerant and can be grown in a really wide array of garden positions, including that most difficult of all situations – dry shade.

In many ways, though, they both grow and look their best when integrated into a shady or woodland border situation, which of course also closely mirrors the habitats of the wild species.

Ongoing care.

Hellebores are evergreen, with flowers emerging before the foliage and on separate new stems.

The main care involved in growing them in the garden revolves around what to do with the previous years foliage. Many gardeners simply do nothing and leave the whole plants intact year round. There is something to be said for this since the old foliage will certainly help protect the soft new stems as they emerge in winter.

New spring flower stems.

However, those old stems and leaves can also act as snail hotels as well as potentially harbouring various fungal diseases, so the alternative approach is to cut all the previous years foliage and stems right back to ground level in mid winter.

This has the added advantage of allowing the new flowering stems to be displayed to their fullest, without last years raggedly, blotched old leaves marring their pristine beauty.

Propagation.

It is possible, with much care and patience, to divide large plants in order to propagate from highly desirable individual clones. In practice though, hardly anyone fiddles around dividing their hellebores, because they are one of the easiest and most reliable garden plants to grow from seed.

A selection of yellows.

Actually, if you leave the seed heads to develop and ripen on the plants then you’re pretty much guaranteed to find a little crop of satellite babies sprouting around their parent the following spring.

It’s great fun, and really very easy to hand pollinate your favourite coloured plants with one another to see what new colours and patterns result, but simply gathering the copious seed that naturally develops will do the job as well.

Although it is released by the plants in late spring and takes around 9 months to germinate – naturally timed to sprout as the same time that the adult plants come into growth – hellebore seed does not store well and quickly looses viability. It’s simple enough to deal with though, and should be sown as soon as possible after harvesting.

No special treatment is needed although the seed does require winter stratification to stimulate germination, so, after sowing the pots/trays etc. should always be kept outside to experience the winter cold.

Pest and Diseases.

Red picotee with dark nectaries.

Again, these are thankfully few and far between. Slugs and snails will attack young shoots but once the leaves have matured they are far too tough to be appealing to any mollusc. Aphids can likewise congregate on new growth and if not removed will lead to distorted and damaged foliage and flowers.

More importantly aphids are also suspected as the agents responsible for passing on Hellebore Black Death – an all too common viral disease that leads to large black streaks and distortion in the foliage, stems and flowers of hellebores.

A much less serious but also quite widespread problem is Black Spot, a fungal disease that causes “dead” brown blotches to appear on the foliage. Removal of old foliage and good general garden hygiene will greatly reduce the occurrence of this and indeed any other fungal problems.


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Camellias.

Friday, March 5th, 2010

Camellia japonica 'Hagoromo'

As winter turns slowly into spring, one of the pivotal moments for me is the opening of the first camellia flower.

These often almost impossibly exotic looking shrubs have become very familiar inhabitants of our gardens, but for most of their British cultivation history they were considered as exclusively conservatory and glasshouse plants, and no one ever dreamed of trying them in the garden.

Cultivation history.

Native to Japan, China and south-east Asia, camellias were revered (and inspired countless works of art) for the last several thousand years in their home lands. Like so many other Asian trees and shrubs, the Victorians introduced the species, together with many named forms, into Europe through the latter part of the 19th century.

Camellia japonica 'Oukan'

By the early 1920’s though, they had all but disappeared from cultivation, having well and truly fallen from favour.

In large part they were victims of the massively increased cost of maintaining, heating and working those glass-houses, most of which were themselves condemned to demolition.

Post World War 2 there was a gradual revival of interest and as the general gardening fashion moved away from labour-intensive herbaceous plantings towards the more self-sustaining shrubbery, gardeners finally started trying camellias outdoors.

It shouldn’t have come as any great surprise that many of these plants were indeed fully hardy – many grow naturally in climates far more severe than our own – but their exotic flowers and foliage had for far too long seen them separated from their close cousins the Rhododendrons.

Camellias in the garden.

Camellia japonica 'Dahlohnega'

In the wild camellias are all very much understory shrubs – and ultimately small trees – which is to say that they naturally inhabit the dappled shade at the margins and in openings in woodland.

Knowing this simple fact, and then imagining what those natural conditions are like, tells you a few key facts about the conditions that they need to thrive in cultivation – 1) shady, but not dark 2) sheltered from the wind 3) with their roots in (acidic) leaf-litter.

Whilst the most frequently seen camellias are, to all intents and purposes, absolutely bone hardy as plants, the same can’t be said for the flowers themselves, particularly the earliest varieties that open in late winter.

Camellia 'Baby Bear'

Shelter from wind is pretty vital if those early flowers aren’t to burn off. Similarly, east-facing sites should be avoided since frozen winter flowers will turn to a brown mush if exposed to the rays of the early morning sun.

A westerly or northerly aspect is ideal, and walls, fences or trees and other (later flowering) shrubs can be used to provide additional shelter.

Much is made of camellias being “acid-loving” and even indicator species of acid soil.

In fact they are considerably more tolerant than most Rhododendrons in this regard, and will happily succeed on a neutral as well as an acid soil.

Camellia japonica 'Black Opal'

Having a good, open, free draining, humus-rich soil (i.e. emulating what they would have in the wild) is actually far more important than the precise pH.

Where soil conditions are totally inappropriate or un-improvable, camellias also make great container plants. Their relatively slow rate of growth means that, with appropriate watering, feeding and repotting, they can thrive almost indefinitely in pots and their formality and glossy evergreen foliage makes them ideal patio subjects.

With care camellias can be planted out at any time of the year, but early spring, whilst the plants are in flower, in the ideal season. Then the roots will still be dormant and the plants will readily establish into their new homes.

The species.

Thanks to the renewed breeding efforts of the last 50-or-so years there are now a truly vast array of camellias from which the gardener can choose.

There are just over 40 wild species, (including C. sinensis, the plant from which we get tea) but virtually all of the widely grown garden varieties derive from 3 of those species - C. japonica, C. reticulata & C. sasanqua – and their various hybrids.

Camellia japonica.

Camellia japonica 'Lily Pons'

Certainly the most important and widely grown of all the species, the Japanese camellia has given rise to an extraordinary 30,000 cultivars and forms – the largest by far of any individual species of plant on earth.

The flower forms are classified into 6 types: single, semi-double, anemone, peony, rose double and formal double, with colours ranging from pure white and pale creams through all shades of pink to deep and vivid true reds. With such a large range of selections it’s not surprising that the bloom time varies considerably with different cultivars opening throughout late winter and the whole of spring – something to bear in mind when selecting plants for any given site.

The highly desirable white flowered forms are unfortunately also the most prone to weather damage and should always be planted with extra protection if the blooms aren’t to be regularly spoiled. The equally beautiful deep red flowered japonicas though are much tougher and can take considerably more harsh weather without getting damaged.

Camellia sasanqua.

Camellia sasanqua 'Yuletide'

This much less well known Japanese species is in many ways more versatile than C. japonica and should certainly be far more widely grown.

The plants flower in mid to late autumn, generally well away from any frost danger, and have a similar (if much smaller!) range of flower shapes and colours to their Japonica cousins.

The individual flowers are smaller and more fleeting than that species, but are produced in huge numbers from a very early age.

They also have the great bonus of being fragrant.

Camellia reticulata.

This extremely showy Chinese species has the largest blooms of any camellia, with huge flowers ranging from single to semi-double in shades of white and pink with a few reds.

They are much less hardy than the previous two species though, and, although they bloom later in spring so are less frequently subject to weather damage, the plants themselves definitely require a more sheltered location in order to do well.


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Winter garden wonders.

Monday, January 4th, 2010

In times gone by the deepest darkest months of Winter were seen by gardeners as fit only for leafing through catalogues of seeds, preferably by some form of open fire, whilst green fingered urges were met by watering the house plants and admiring seasonal indoor plants. These days, though, most folks want their gardens to deliver for them all year round, and whole plots and entire books are devoted to groups of garden plants that are at their prime in January and February.

Hamamelis - Witch hazel flowers open even when encrusted with ice and snow.

You certainly don’t have to go as far as dedicating all of your growing space to a single season to reap the rewards of winter gardening. There’s definitely a special kind of satisfaction that comes from seeing a blazing red Witch Hazel bursting improbably through snow and ice, or from having the heady perfume of a Viburnum waft gently through the air. What’s more, the addition of a few select seasonal gems into a garden will encourage you off the Christmas sofa to get out and about to investigate their progress.

There aren’t too many pollinating insects around in January so a common feature of lots of winter flowering shrubs is small flowers with a powerful perfume to entice those bees brave enough to take to the wing. Low-growing Sarcococca (Christmas Box) is so non-descript in flower you might well tread on it were it not for the knock-your-socks-off fragrance that demands your attention. Lonicera x purpusii ‘Winter Beauty’ is a  popular shrubby Honeysuckle with small white flowers that also pack a powerful scent and is pretty much foolproof to grow in almost any situation.

Chimonanthus praecox - a sublime gem for the winter garden.

With it’s pretty lantern-like hanging flowers of primrose and burgundy the medium-sized shrubby Magnolia relative Chimonanthus praecox (Wintersweet) is rather more sophisticated and also provides a delicious perfume. Although it’s not often seen outside of big gardens it’s readily available and should be grown far more often than it is.

The image of Mahonias has become a bit tarnished lately, mainly due to their use in virtually every municipal park planting throughout the northern hemisphere. Still, there’s a good reason why they are so widely grown – dramatic, large, spiky, evergreen foliage, a tolerance for shade and the production of large racemes of very fragrant, canary-yellow flowers in Winter. In many ways these are the perfect shrubs for town gardens.  Viburnums are almost as popular, and the best of the winter flowering varieties, such as V. farreri, and V.x bodnantense ‘Dawn’ never fail to please with their clusters of pinky-white fragrant flowers.

If you have a wall that you’d like to see come alive in winter then Clematis cirrhosa is probably the number one choice. This moderately strong climber has delicate, fern-like evergreen foliage and really pretty, cream-coloured bell-shaped flowers that have a delicate scent. A number of forms are widely available, I particularly like ‘Freckles’ which has petals splashed with crimson on their inner surface.

Daphne mezereum - one of the finest native wild flowers for fragrance.

One of our more unusual wild flowers, Daphne mezereum is a British that thrives on chalky soils. This is one small shrub that delivers big time in winter with beautiful flowers of purple or pure white that have the most intoxicating fragrance.

Possibly my personal favourite winter shrub of all though is a Daphne relative from China – Edgeworthia chrysantha, the Paper Bush. The flexible bark of this beauty was traditionally made into bank notes, but unless you’re planning your own small-scale printing operation, you, like me, will be more drawn to the tubular, fragrant flowers of pale yellow. The form ‘Red Dragon’, if you can find it, is even more beautiful with impossibly exotic bright red flowers that, on a sunny winters day (and possibly depending on what you’ve been drinking the night before) might just convince you that you’re in the Caribbean.

Hamamelis (Witch Hazels) are firm favourites that can be found in most larger gardens. The old hybrid ‘Pallida’ is still hard to beat on the scent front, but there are a range of new-ish hybrids arriving from breeders in Belgium that deliver much larger flowers with the same awesome perfume. Colours vary from pale yellow through copper orange to blood red. ‘Nina’ is the finest of all the yellows and I particularly love the dramatic, large burnt orange flowers of recently introduced ‘Aurora’ and ‘Aphrodite.’

All of these shrubs work hard to drive away the winter cold and also serve as handy a reminder that Spring is just around the corner, but some trees are also at their best at this time of year. Birches can be rather understated small trees for much of the year but the best of them really come alive in winter. Then, with the leaves long since disappeared, the colours and textures of their often-fabulous bark are fully revealed. I’ve become a huge fan of Betula albosinensis, in particular, and seeing the low winter sun illuminate the peeling deep scarlet and bright pinky-orange bark of the many different forms is without doubt the highlight of my own garden in winter.

Betula albosinensis - a great centrepiece for any winter garden.

Of course none of these winter wonders should be planted in winter itself, but by checking out what’s looking good now it’s easy to plan ahead for a Spring planting. Unless your soil is truly dismal, then the best advice for planting all trees and large shrubs is simple: the only garden supplies you need are a spade, a fork, a short sturdy stake + tie, if your plant is tall or top heavy, and a willing digger-of the-soil…that would be you or a trusty assistant.

All of your planting time and efforts should be focussed on making a wide planting hole and breaking all of the soil into small, crumbly pieces, this way your new plantings will be able to get their roots out into the soil easily and will establish quickly.  DO NOT add compost into the hole, this damages the natural bacterial balance and can easily lead to root rot, as well as slowing down the progress of the plant into the soil where it will, after all, be spending the rest of it’s life. Instead mulch well on top of the planting, but don’t cover the stem of the plant, and the worms will do the rest.


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