As the seasons change from autumn to winter, the greenhouse turns from a productive central hub in the garden that has been the source of tomatoes, cucumbers and chillies throughout the summer period, into a place to overwinter less hardy plants and a place to start the preparation process for the upcoming growing season to come.
Remove old Plants
The first job on the list should be to remove any none productive plants. Cucumber and tomato plants will no longer be productive, but could run the risk of harbouring disease. To reduce the likelihood of this, remove them to prevent the risk of leaving anything nasty that could adversely affect the subsequent seasons growth.
Empty the Greenhouse
The next job is to give the inside of the greenhouse a thorough deep clean. It is advisable to watch the weather on this one and to choose a dry and mild autumnal day. This enables you to move all plants and pots outside, freeing up the space to give the greenhouse a good clean. Our Gabriel Ash greenhouse staging for both our classic and RHS greenhouses is designed to be easily removed. This makes cleaning the greenhouse and the staging much easier.
With the greenhouse empty you can start the cleaning process. Firstly with a clean soft brush start in the roof of the greenhouse clearing away any cobwebs and loose dust and dirt on any ledges, blinds, shelves, etc. Working from top to bottom and down the side walls, gather all the dirt and detritus in a pile and can later be put on the compost heap.
If you grow in soil or compost beds in the greenhouse you should also clear out any spent compost and replace this every couple of years with fresh compost or soil. This will reduce the likelyhood of harbouring any unwanted pests and diseases in the soil.
The next step is to give all the frame and glass a good clean using a soft scrubbing brush and hot soapy water with some horticultural disinfectant added (e.g Jeyes Fluid). Take care to thoroughly wash the glass both inside and out. Even slightly dirty glass can cut out the light entering into the greenhouse. Clean glass can make a big difference to light levels over the winter months when the days are so much shorter. If you find any build up of algae where the glass meets the frame scrape this away; a plastic plant label is ideal for this job. When the greenhouse has had a thorough scrub with the hot water, rinse the greenhouse off with a hosepipe ideally set to a fast jet spray. You might want to finish the deep clean by using a squeegee to thoroughly dry the glass and remove any water streaks, you could also use a wash leather for this.
While you are cleaning the greenhouse, we also recommend that you check the gutters for any blockages from falling leaves and twigs. Clean out all the gutters as part of the preparation for winter.
Other things to clean
Once thoroughly washed, leave the doors and windows open to allow the greenhouse adequate ventilation, this will speed up the drying process. While the greenhouse is drying you can turn your attention to giving the staging you have removed a good scrub and also any pots, etc. will also need a good clean. If you have terracotta pots you might find it easier to soak the pots first to help remove all traces of compost. Thorough cleaning can not be over emphasised to minimise the chance of diseases or eggs of pests overwintering, causing problems to crops in the next season.
Winter Ready Greenhouse
Once clean and dry, start by re-positioning your greenhouse staging and shelving. Then you can bring back in all your tender plants, cuttings and pots. It is a good idea to store a couple of full watering cans in the greenhouse or fill up a trough with water. This ensures that any watering that is required over the cold months the water is at the same temperature as the greenhouse and not straight from an icy water butt.
What Can I Grow
Although the greenhouse in winter is less productive and is normally a place to store tender plants there are still a few plants that can be grown to crop. Crops of herbs like chives, coriander, mint and parsley can be kept in pots for use in the kitchen. Keep the pots moist but not waterlogged and pick as needed. You can also keep growing autumn/winter salad mix leaves in pots. Again ensure the compost does not dry out and pick as required. You could get a few pickings from these but they will not go on for ever and will certainly be finished by late December and into January.
Getting the greenhouse ready for winter is one of the last major projects in the build up to winter. A thorough clean at this time of year is the best preparation you can give your greenhouse ready for the new season ahead. Although this process might sound like a lot of hard work, the rewards of being able to escape to your spring ready greenhouse over the long cold winter months can not be understated.