There are few gardening jobs I enjoy more than giving the greenhouse a thorough spring clean. There’s something hugely satisfying, after being cooped up indoors over winter, about getting the greenhouse ready for the growing season to come. And February is the best time to tackle this job so that the greenhouse is ready for all that seed sowing in March.
It’s crucial that germinating seeds get as much light as possible so that means cleaning away the layers of dust and dirt that have built up on the glass over winter. It’s also a good idea to make sure there are no pests holed up in the cracks and crevices of the greenhouse, waiting to emerge just as your plants start to grow.
Pick a mild, dry day and remove everything from inside the greenhouse, as a top to bottom clean is what’s required. Temporarily move any overwintering plants to a sheltered corner and cover them with several layers of horticultural fleece to give them some protection from the cooler outside temperatures. Alternatively move them into the shed or garage while you’re doing the cleaning.
Remove everything else: pots, bags of compost, tools and, if possible, the staging, too. Sweep the floor to remove any debris and old compost – a dustpan and brush is useful for tight corners. Then, with a bucket of hot, soapy water and a cloth, wash the frame and the glass. Use an old toothbrush or a plastic plant label to get into the gaps between the frame and the glass where algae, moss and dirt can build up. Wipe down the staging and move it back inside.
Before you return anything else decide whether or not you need it. It’s easy, even in a greenhouse, for clutter to gather: broken bits of pot, old plant labels, rusty tools and old seed packets, so now’s the time to be ruthless!
Keep broken terracotta pots to use as crocks in the bottom of containers, and give old tools a clean with wire wool, sharpen them if necessary using a sharpening stone and wipe down with WD-40 or vegetable oil. If you have too many pots and trays, put grey plastic ones in your recycling box and donate black ones to a community garden, or see if your local garden centre or nursery will reuse them. Wash the remaining ones so they’re ready for a new batch of plants and stack them neatly.
According to the RHS, compost shouldn’t be stored in a greenhouse as it can heat up and potentially encourage the bacteria responsible for Legionnaires disease to form, so instead keep compost bags in the shed or garage.
Upcycle kitchen jars and repurpose Tupperware as storage for plant labels, twine and ties and all those other bits and bobs so that you have everything to hand.
Before you move the plants back inside, remove any dead or yellowing foliage and any weeds growing in among them. Check for pests too – under the rims and the bottom of containers are the best places to look, particularly for slugs, snails and earwigs.
Now to tackle the outside of the greenhouse! Always make sure you can safely reach where you’re trying to clean and never rest your body weight on the glazing. For awkward to reach spots use long-handled tools. Clean out leaves and gunk that will have built up in the gutters, then wash the glass and frame with hot, soapy water and rinse using a hose. Your greenhouse should be sparkling now and all set to be filled to the brim with seed trays and pots.
Written by Louise Curley