Practical and functional, no garden should be without a greenhouse.

Installing a greenhouse is one of those pivotal moments for any gardener. Having a covered area in the garden, be it a conservatory, porch or even a cloche or cold frame, greatly enhances the scope of what you can grow and when, but once you have a greenhouse you’ll wonder how you ever managed without it.

Greenhouses create longer growing seasons, provide protection, warmth and additional humidity for their leafy occupants. They allow you to grow entire ranges of plants, both edible and ornamental, that wouldn’t otherwise be possible.

Seeds can be sown much earlier and bulbs and containers started safely into growth in late winter or early spring. Perhaps most important of all, greenhouses also provide a sheltered, dry and wind-proofed working environment which will work wonders to encourage you out into the garden on otherwise grey, cold and uninviting days.

Site.

A wooden potting table - essential greenhouse kit.

Generally speaking you might have only limited possible sites available in your garden, or quite possibly no choice whatsoever as to where to situate a greenhouse. There is a temptation to locate them as you would a shed – i.e. tucked away out of site in an unused and probably uncultivatable corner of the garden.
Unless you’re planning to house a specialist fern collection in your greenhouse, this kind of location is really not going to work. Another common mistake is to situate with the longest side facing due south into the sun. This will create unfeasibly high summer temperatures and you may end up oven-baking all your plants as a result; at best you will be continually struggling to keep ventilation and humidity high enough and may end up having to shade the entire greenhouse in an effort to keep things stable.

Where possible the very best site will have the longest sides of the greenhouse facing east and west, the door/ventilation end facing south and the northern end against the protection of a wall, hedge of fence.

Choice of greenhouse.

A typical flat-pack aluminium greenhouse.

The best value greenhouses are those that come flat packed for self-assembly. If you have the patience and (ideally) a couple of willing helpers on hand then these aluminium and glass constructions are extremely good value and can provide an ideal solution.

Go for the very largest size that you can afford and can accommodate. You may not think that you’ll fill up all that space, but believe me, no matter how large your greenhouse you will soon find yourself wishing you could squeeze in a little more.

Also the larger the enclosed space the more stable the humidity, temperature and environment within, and the less susceptible it will be to heat loss overnight and over-heating during the day.

Finally, ventilation is an absolutely part of any greenhouse so make sure that yours has as much as is available, preferably allowing for a cross flow of air from end to end and/or side to side of the structure.

Access to services.

In order to make the most of your greenhouse you will need access to electricity and a water supply. Once you have a collection of plants under glass you will want to ensure they don’t get hammered by extremes of cold, and, depending on what you are growing, you may also need to guarantee a frost free environment year round.

A water butt set up to collect run-off from the greenhouse roof.

There are a variety of gas heaters available, but they can be tricky to run and expensive to buy. The best of them also need to be installed by a qualified engineer, and might end up costing more than the greenhouse itself. Having power available in your greenhouse will allow for cheap and easy low level heating if and when it’s needed and of course will also allow you to add a light for those dark winter days.

Access to water is even more important, since you’re going to be using this, quite possibly on a daily basis, for a large portion of the year. Consider installing a tap or at least running a dedicated hose to the greenhouse, and most definitely install a water butt to capture the rain that falls on the large glass surface of your greenhouse. Using captured rainwater not only makes good environmental and economic sense but is also far better for all plants, and absolutely essential for the likes of Orchids & carnivorous plants as well as many seedlings.

Think also about your own access to and from the greenhouse and consider adding some additional paving or gravel in order to keep the entrance clean and prevent mud being traipsed in from a soggy wet garden.

Cleanliness.

All of the warm, humid & sheltered conditions that allow for great plant growth will also create an outstanding breeding ground for fungi, bacteria and plant viruses, not to mention weeds and a whole gaggle of flying insect pests. Keep work surfaces, glass and flooring clean, tidy and hygienic and you will greatly reduce the opportunities for any of these nasties to gain a foothold.

Greenhouses are not garden sheds and should not be used as dumping grounds for all the things that you want to tidy away – the transparent sides should put the kibosh on that idea anyhow, since everything inside is effectively still on display.

Equipping a greenhouse.

There are a few useful bits of kit that you should have lined up ready for your new glassy space. Top of the list is a solid, steady work surface set at a height comfortable for you to work with and strong enough to hold pots, compost and whatever else you’re likely to need. Consider using a table and perching seat – they don’t take up much room and make can make working conditions far more comfortable.

Working tray.

A large, shallow sided tray is also pretty essential. This will allow you to do a whole range of gardening tasks – mix composts, pot up plants, turn out old pots etc. – and all in contained, clean and hygienic conditions.

You’re also going to need an easily accessible and preferably containerised or divided tidy or storage area for tools, labels, pens, ties, plant foods and so on. Think about layout too, and where best to accommodate composts, pots, trays, canes and all the other items so that they are ready for use.

I like to have two separate bins running in the greenhouse. In fact it’s the very first thing that I set up and won’t start any work without them, as it’s amazing how much debris you produce whilst working in a greenhouse. Much of it can be composted, but some things, like old broken plastic pots and seeds trays or diseased plant material, need to be kept separate for waste disposal.

Shade netting - have some on hand long before it's likely to be needed.

Tools will vary according to your needs and the nature of what you will be growing, but secateurs, scissors, a hand watering can and a couple of sprays are all pretty indispensible in my experience.

Finally, unless you have indeed been forced to locate your greenhouse in a dark, shady corner where a shed might otherwise live, then you will almost certainly need some shading ready for extremes of temperature.

You can easily attach shading net to the inside or your glass walls, and some greenhouses come with their own shading systems too, but in either case you’ll need to have it ready to use well in advance of summer.