Collection: By Size - Greenhouse

Greenhouse Sizes: What Each Footprint Allows

Greenhouse size decides two things: what you can grow, and how comfortably you can work while growing it. Both matter, and the second is the one most often underestimated. A house you have to reach into rather than move around in gets used less.

The range is grouped by floor area rather than by frame dimensions, because floor area is what determines the layout you can fit inside. Below are the bands and what each one realistically holds.

Under 5 m2

A small greenhouse suits a patio, balcony or courtyard where a walk in frame will not fit. It holds herbs, salad crops and container flowers, and most models assemble in an afternoon without a concrete base. You will be reaching in rather than walking in.

Below about two square metres, a mini greenhouse or cold frame is the more sensible format. It does the propagation and hardening off jobs well without pretending to be a growing space.

5 to 10 m2

This is the most common size in British gardens. There is room for staging along one side and a bed along the other, with a path between wide enough to use a watering can in each hand. It takes a full season of tomatoes, cucumbers and salad without crowding.

For most gardens this band strikes the closest balance between capacity and footprint.

10 to 20 m2

The step up from a starter frame. There is room for staging on both sides, permanent beds, and tall crops such as vine tomatoes and trained fruit with the headroom they need. A larger volume of air also holds temperature more steadily overnight.

At the upper end of this band the central path becomes wide enough for a barrow, which changes how the house gets used day to day.

20 m2 and Above

At this scale the house supports permanent beds down both sides, wide staging runs and comfortable circulation with equipment. It also allows zoning, so one end can be held warmer than the other and tender stock overwintered without heating the whole volume.

The trade offs are groundworks and running costs. A large greenhouse needs a level, drained and square base, and heating cost scales with cubic volume rather than floor area.

Measuring Before You Choose

Measure the ground you have, then subtract what you need around the structure. A greenhouse needs clearance for the door to swing, room to walk around it for cleaning and glazing repairs, and enough distance from a boundary that you are not working over a fence.

• Allow at least sixty centimetres clear on the door side.
• Leave access to all four sides if you can, for cleaning and pane replacement.
• Check what shades the site through the day, not just at the moment you measure.

One consistent piece of feedback from growers: buying too small is regretted more often than buying too large. The cost difference between adjacent sizes is usually less than the cost of replacing a frame two seasons later.