Your First Greenhouse

A greenhouse isn't one thing. It's a lean-to bolted to a south wall, a squat polycarbonate dome on an allotment, a Victorian-style aluminium frame in a back garden, or a cold frame sunk into the earth beside your beds. Before you spend money, decide what you're trying to do. Extend the tomato season by six weeks? Start seeds in February without a windowsill covered in pots? Overwinter tender perennials? Each goal points toward a different structure, a different size, and a different price.

The single most common mistake is buying too small. A 6×4 ft greenhouse sounds generous until you fill it in April and have nowhere to put anything. If your budget and space allow, go one size up from what you think you need. The second most common mistake is buying glass when polycarbonate twin-wall would do the job better for most UK climates: lighter, warmer, less likely to shatter, easier to cut.

Cold frames: the honest starting point

If you've never grown under cover before, a cold frame costs almost nothing and teaches you everything that matters: hardening off, ventilation, condensation management, slug pressure. Spend a season with one before committing to a full structure. You'll know exactly what you want from a greenhouse by the time spring arrives.

Polycarbonate freestanding: the practical workhorse

Twin-wall polycarbonate panels trap a layer of insulating air between two sheets. They're roughly ten times the impact resistance of glass, block some UV, and are straightforward to replace if one panel cracks. Aluminium frames are maintenance-free. This is the category most beginners should buy into. Palram and Eden are the dominant brands in UK garden centres and both have strong spare-parts availability.

Lean-to: working with a south wall

A lean-to greenhouse is fixed against a house or garden wall, using the masonry as one side and as a heat store. The wall absorbs warmth through the day and releases it overnight — useful in UK winters. The trade-off is limited headroom on the wall side and a fixed orientation. If your south wall has the space, a lean-to is often warmer than a freestanding structure at the same price.