Greenhouses and cold frames are an essential aid for many gardeners. It’s important to keep your greenhouse clean and tidy to prevent pests and diseases spreading rapidly in the humid and heated conditions. But we are none of us perfect. So setting yourself the task of cleaning the interior and exterior of your greenhouse just twice a year is achievable.
A regular clean twice a year will help maintain the structure of your greenhouse. This is particularly important if the frame is made from wood and therefore prone to rotting. Even aluminium greenhouses benefit, as they can develop moss and mould along the frame.
Cleaning your cold frame is another task that needs doing regularly. And it makes sense to do both greenhouse and cold frame at the same time.
Late winter/ early spring is one time to carry out these gardening tasks, and early /mid autumn is another. By mid autumn your tender crops will have been harvested, but the days are still warm enough for tender perennials such as citrus trees to be happy enough outside whilst you get on with the cleaning.
Temporary Greenhouses
If you have one of the more temporary plastic greenhouses it will still need cleaning. Perhaps you tidied it away as it wasn’t needed during summer? In which case, put it up now to give it a clean with warm water and vinegar. Allow it to dry out before folding and storing. Or before putting your plants in to over winter.
Cleaning your Greenhouse
If you can, clean greenhouses on a moderately windy day. That way, the breeze will help to dry out the greenhouse as it’s washed.
Firstly, check the panels for any broken or cracked glass. These panes should be replaced. If you are planning on doing the job yourself, then you should wear proper gloves and goggles.
If you have an electricity supply to the interior of the greenhouse, ensure that the electricity is turned off before you start cleaning. Yes this sounds like stating the obvious, but you’d be surprised how many people forget to turn off the electricity!
Before you clean inside, do the obvious of removing all the containers, pots and shelving/staging that can be removed. Throw out old, used grow bags. Sweep the floor to remove any dirt, spilled soil and leaves that have fallen from the plants.
Dirty windows affect sunlight levels and over winter there’s less daylight generally. So to maximise the light your over wintering seedlings, tender and young plants are getting, wash the panes of glass with warm water. Add a dilution of vinegar 1:8 for extra cleaning power.
The higher parts of the greenhouse roof can be reached by attaching a sponge to the end of a bamboo cane. Remember to wash both the inside and the outside of the panes.
Preparing for Winter cold
Once the panes of glass are dry, insulate the greenhouse with bubblewrap or horticultural fleece. This will help to protect any plants you are overwintering. It also enables the greenhouse to heat up more rapidly in the spring.
Insulating temporary plastic greenhouses with horticultural fleece is an extra layer that can help you over winter plants that might not otherwise survive.
Remember to brush down and scrub any brick walls, paths and fixed staging you have inside the greenhouse and cold frame. Use a suitable proprietary disinfectant, or make your own recipe using vinegar as above, plus 1 tbsp bicarbonate of soda per litre of water.
If you can’t stand the smell of vinegar, then add a citrus essential oil or lemon juice instead. This will help both with the cleaning and with the pest and disease removal.
Wooden frames of greenhouses and cold frames can be painted using a wood preservative. It’s much easier to do this before you put the plants back in, but if you need to do it when they’re in, be sure that none of the preservative touches the plants.
Also check that all ventilation panels and windows are operating properly and lighting and watering/irrigation systems are working.
Cleaning out of plant pots can be left until winter. After all, you’ve got plenty of other tasks to be doing in the autumn garden!
And if you’d like a gardening course on using your greenhouse to the full, learning more about your garden and gardening, why not ask about our bespoke Gardening Lessons, where your classroom is actually your own garden. We can help you learn gardening basics, carry out worm and other experiments and also show you how to plan an ornamental border or kitchen garden.
And for further gardening advice and inspiration, check out Plews Potting Shed blogs, including the selection below and our monthly Tipsheet – You could come and find us on Instagram Pinterest and Facebook too.
Related Gardening articles from the award winning Plews Potting Shed
Making your Greenhouse ready for Winter
Autumn Pruning – some Questions and Answers
Do You have any Greenhouse Plans for this Year?
Autumn Gardening Tasks: Your Lawn
Autumn Gardening Tasks – Lifting Perennial Tubers
