Polytunnels on an allotment

You can only have a polytunnel if your site allows it, and many don't. Where they're allowed you'll usually need written permission, and possibly planning permission too.

A polytunnel is the biggest thing most plot-holders ever put up. It's also a big structure on a small piece of rented land, so start with the rules before you look at kits.

Can you have one?

Not all sites allow polytunnels or greenhouses, so check your terms and conditions carefully.

Where they are allowed, you'll often need written permission first. Bolton Council, for example, asks tenants to get written permission before putting up a shed, greenhouse or polytunnel. Ask your site:

• Are polytunnels allowed, and is there a maximum size or height?
• How much of the plot can be under cover?
• Where can it go, so it doesn't shade a neighbour?
• What happens to it if I leave?

Planning permission

Site permission and planning permission are separate. Welsh Government guidance says you should get both.

Wales. For planning purposes, a polytunnel counts as a "greenhouse". Allotments have permitted development rights for one greenhouse (plus one shed) on plots of 125 sq m or more, or one greenhouse or one shed on plots from 62 to under 125 sq m. Each must be no more than 6 square metres in ground area and 2.2m high. Plots under 62 sq m, and sites in protected areas such as National Parks and conservation areas, need a planning application. Anything bigger needs planning permission.

England, Scotland and Northern Ireland. VERIFY: find official guidance on planning permission for polytunnels on allotments in England, Scotland and Northern Ireland. Ask your site and your local planning authority before you buy.

Sizing it for your plot

Measure the space you can spare, then check it against your site's limit and (in Wales) the 6 square metre permitted development cap. Leave room to walk round it for repairs and re-covering.

Use the plot planner to see how much growing space you'd lose outside, and our layout guide for where it might sit.

Watering under cover

Rain doesn't reach crops in a polytunnel, so all the water comes from you. Water less often but thoroughly, at the base of the plants, ideally early in the morning. If your site allows it, a water butt fed from the tunnel or a nearby shed roof saves a lot of carrying.

What to grow

A polytunnel suits crops that like warmth and shelter. Common choices are tomatoes, peppers, cucumbers and early salads. VERIFY: source a list of crops suited to polytunnels from the RHS before keeping this sentence.

Tomatoes are in the same family as potatoes and share blight. Blight is most common in warm, wet weather and its spores travel on the wind. Rotating crops under cover is harder than outside, but the RHS principle still applies: grow related crops in a different spot each year.

FAQs

Can I put a polytunnel on my allotment?

Only if your site allows it. Many don't, and those that do often need written permission.

Does a polytunnel need planning permission?

In Wales, small polytunnels on allotments can be permitted development within limits. Elsewhere, ask your local planning authority.

What size polytunnel for a half plot?

There's no standard answer. It depends on your site's limit, your plot's shape and how much outdoor growing space you want to keep.

Your next step

Ask your site whether polytunnels are allowed and at what size. If yes, mark out the footprint in the plot planner before you look at kits.