Siting a greenhouse | gardenersworld.com

Plant features

Where you place a new greenhouse or polytunnel can make the difference between growing success and failure, so it’s important to get it right. With careful siting, it should be possible to optimise the productivity of your structure, which helps to offset your initial outlay and justify the space it takes up in your garden.

Of course, it may be that there is only one possible place you can put it, but if you do have a choice, it’s well worth giving it the best possible position you can. It may seem a shame to sacrifice a prime location or an already productive spot in your garden, but when you weigh up the increased benefits you’ll get from protected cropping, it’s a sacrifice worth making.

Think about what you want to do with your protected structure, and what the needs of your plants will be. If you’re planning to grow crops in there all year round, raise seedlings or overwinter tender plants, you’ll need a spot with maximum light and sunshine, away from frost pockets and cold winds.

Discover the six essentials of siting a greenhouse, below.

Close-up of a gardener clearing debris from greenhouse guttering

Good light

Don’t put your greenhouse directly under trees. They’ll cast unwelcome shade, which encourages green algae to build up, while falling branches and leaves can cause damage and block guttering. Honeydew from insects on the foliage of trees can make the glass or plastic sticky and dirty, so it lets in less light. Tree roots can also upset the foundations and make planting directly into the beds inside tricky.

Convenience

As you’ll be visiting your greenhouse or polytunnel regularly, particularly during the summer, make sure it’s easy to get to and as near to the house as possible. Whether your visits are for daily watering, opening and shutting doors and vents, or just nipping in to pick a few tomatoes for your lunch, you want it to be close at hand.

Level ground

Avoid putting your greenhouse or polytunnel on a slope, if possible. Although it is technically possible, it would make things complicated, as the staging inside needs to be horizontal. Definitely don’t site it at the base of a slope, as this is often a frost pocket where coldness lingers – that doesn’t make for successful winter growing.

Orientation

If you want to grow crops all year round, it’s best to line up the ridge of the structure to run east-west, as this will maximise light during the winter. It will also help it to heat up more quickly after cold nights. If you intend to grow summer crops only, then aligning the ridge north-south is preferable as it gives an equal amount of sun to each side and helps to reduce overheating on the hottest days.

Easy access

Ensure there is at least 1m of space all around your structure. Not only does this make putting it up easier, but it’s useful when panes or covers need replacing, and when cleaning or simply walking past. Leaving this space will also mean that fences and other structures aren’t close enough to cast shade or hinder ventilation. With polytunnels, always allow plenty of space at the front too, as opening the door is usually the only way to ventilate it – and good air circulation inside is vital.

Good soil

If you’re planning on growing in the beds inside your structure, choose a spot with decent soil, if you can, as you’ll be asking a lot from it. Poor soil can be improved by digging in organic matter, and raised beds are an option, particularly in a polytunnel. Try to avoid stony or rocky ground, as it can make the construction process very problematic.

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Talkback: Siting a greenhouse

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Callander Girl 17/01/2013 at 22:28

If you set your greenhouse on slabs, make sure the upper surface isn't 'riven' as that lets water drain in whenever it rains!

flowering rose 18/01/2013 at 13:55

and if not even and set secure ,youll find they lift and like me you ll trip over.