— warm glass, tomato leaves gone slightly tired, the last of the basil holding on. I always know it’s time to start closing things up for winter when I catch myself reaching for a jumper before I’ve even opened the greenhouse door in the morning. This week felt like that moment.
Getting a greenhouse ready for winter isn’t complicated, but it does reward a bit of unhurried attention now, while the weather is still mild enough to actually enjoy being out there. Leave it too late and you’re doing all of this in the cold, with frost-tender plants already suffering. Here’s the checklist I work through every year, roughly in order.
- Give the glass (or polycarbonate) a proper clean. Grime and algae on the panels block a surprising amount of light right when your plants need every bit of it. A soft brush, warm water and a little diluted washing-up liquid does the job — rinse well so nothing streaks. Clean glass also means less shadow for pests and fungal spores to hide in over winter.
- Sort the ventilation before you insulate. It sounds backwards to think about airflow just as the weather turns, but stagnant, damp air is what causes grey mould and blackleg over winter, not the cold itself. Check that vents and louvres still open and close smoothly, and clear out any leaves or debris that have gathered in the tracks over summer.
- Bubble-wrap insulation, done properly. Horticultural bubble wrap (the large-bubble kind, not the packaging stuff) pinned or clipped to the frame keeps several degrees of warmth in on a cold night. I leave a gap around vents so I can still get airflow through on milder days — fully sealing a greenhouse for months does more harm than good.
- Bring in what actually needs to come in. Not everything does. Hardy perennials in pots are usually fine outside with a mulch. But pelargoniums, fuchsias, tender salvias and anything semi-tropical you’ve been enjoying on the patio need to be under cover before the first proper frost, which in most of the UK and much of central Europe is only a few weeks away now.
- Give your tools and staging a proper tidy before you lose the light for it. A greenhouse that’s organised in September is a much nicer place to duck into on a grey February afternoon than one you abandoned mid-task in October. Wipe down staging, sharpen and oil secateurs before they go into storage, and clear out anything that’s finished for the year.
- Think about frost protection for the greenhouse itself, not just what’s inside it. A small heater or even just a max-min thermometer so you know how cold it’s actually getting overnight makes a real difference in deciding what needs extra protection. I’ve rounded up the greenhouses, growhouses and tool storage I’d actually recommend, sorted by size and budget, on the English Cottage Living Greenhouses & Tool Sheds page.
- Do one last pest check before you close up for the season. Vine weevils, aphids overwintering in leaf litter, slugs tucked under pots — fifteen minutes now saves a much bigger headache in spring. Tip out and check any pots you’re bringing indoors before they cross the threshold.
None of this takes more than an afternoon, spread over a weekend if you’d rather. What I’ve learned over a few winters of getting this right (and a few of getting it badly wrong) is that a greenhouse put to bed properly in September comes back to life so much more easily in March. It’s one of those small, unglamorous jobs that makes the whole gardening year run more smoothly.
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