Greenhouse Advice

You have a patch of lawn, a greenhouse on order and a builders’ merchant ready to sell you concrete. Stop at the lawn. On firm, level soil, both of our greenhouses stand on the ground anchors that come in the box, and the base you need is a level, firmed strip of ground. A hard base earns its place on paving, on soft or made-up ground and on a slope, and each kind has one detail that decides whether the doors still close cleanly.

What decides whether a wooden greenhouse goes up in a weekend or fights you for a week? The base, and one habit: leaving the bolts loose until the whole frame stands. Timber that is fixed tight too early locks in every small error, and the door is where you notice. Here is the job in the order the NORDIC manual sets out, from the base to the last panel, with the checks that keep it square.

The four design choices that decide whether your greenhouse stays standing in a Force 9 — and what you can do about an existing structure.

The number that decides what you can grow is the width. Width settles whether you get a bed on each side of a path or a single bench along one wall; length only adds more of the same. So choose the width for the way you want to work, then add length for the plants you want, and check the plot, the base and the planning rules before you settle on a size.

In short: aluminium is lighter, cheaper and never rots, so it suits a sheltered garden on a budget; a timber frame holds overnight warmth better, sits more solidly in wind...

Updated April 2026: figures and temperature data revised to reflect the 2025-26 growing season. Written by the Waldenhaus team On a hard January night, the instinct is that glass, the...