How to prepare your greenhouse for winter
Move things out
The first thing to do in your post-summer greenhouse is move out plants when they’ve finished their harvest. Several greenhouse fruit and veg, such as tomatoes, are prone to disease, so evicting them sharpish reduces the chances of them leaving behind anything nasty that can adversely affect the subsequent growing season’s plants.
Besides growing matter you should also remove pots, trays, supports and other items when they’ve finished their use, giving them a thorough scrubbing before they’re allowed back in.
When the greenhouse has been emptied, give it a sweep to tidy away any lingering detritus. If you plant directly into the greenhouse soil then you should also clear out the spent compost at least every few years and replace with fresh soil and compost to avoid a build-up of the unwanted pests and diseases that can dwell beneath the surface.
Clean inside and out
You’re now ready to give your greenhouse a clean. Pick a dry day and, if there are any plants that need to stay under glass, keep them in an alternative warm location (or cover them with fleece outside) while you’re scrubbing. For cleaning duties, you’ll need a bucket of hot water, some greenhouse-friendly disinfectant (such as Jeyes fluid), a sponge and something narrow and flexible to flick out dirt from crevices within the greenhouse frame—a plant label or strip of plastic cut from a ready-meal dish make great dirt-flicking devices.
Once those crevices have been emptied, it’s time to scrub. Make sure the whole greenhouse gets your full attention, wiping away all traces of dirt and grime from the panes and the frame.
It’s important to thoroughly clean the inside and outside of the greenhouse. Not only will this give your greenhouse an extra sparkle but it will maximise the amount of light and warmth that gets through—increasingly precious things during those short, cold winter days.
When you’ve finished cleaning make sure you leave windows and doors open for a while to give the greenhouse some good ventilation and time to dry.
While scrubbing you might also notice bits of the greenhouse that need fixing or replacing, giving you the chance to mend them before the hectic growing season begins again.
Move things inside
Now that you have a clean, safe environment for plants you can consider what you want to use your greenhouse for throughout winter. Some people simply use their greenhouses for overwintering—giving frost-sensitive outdoor plants a bit of extra warmth during the winter months before they’re able to go back outside. This is more effective for people with heated greenhouses, so if you don’t have that luxury then consider giving plants an additional blanket of warmth with fleece or bubble wrap.
You can, of course, use your greenhouse as a place to sow seeds in pots and trays—being away from wind and rain is not only beneficial to the young seedlings but also a much friendlier place for the human doing the sowing. Late autumn sown veg and flowers, such as broad beans and sweet peas, will welcome spending their early lives under glass, and you can also use your greenhouse to get a head start on spring sowing—while there’s still space before those hothouse favourites start to fill the space.
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