The greenhouse can be an unappealing place over winter. Most look rather deserted after the last tomatoes have been picked and they cease to be regular port of call in the garden. You might have thought that your greenhouse would be a winter refuge, but in reality most are deserted until the spring clean out ready for the first seeds to be sown in spring. Whenever you tackle it a good winter clean-up is essential and the sooner you get on with it the better. It’s a bit like servicing the lawn mower. It’s much better to do it when you are not using it rather than just when you want to.
A greenhouse is a closed environment designed to protect your plants. However it is also a protected environment for some of the unwanted visitors that pose a threat to your plants next season: overwintering insect pests and fungal spores. A good clean-up is the ideal opportunity to remove them. Never underestimate the importance of good garden hygiene in pest control.
First clear out any plant debris. Most can be composted and any old growing media can be spread on the garden or added to the compost heap. Store any garden chemicals, fertilisers or gardening equipment that is not in use in the shed. The damp, light environment of a greenhouse is no place for packets and bottles. Next wipe down the glass and all surfaces to remove dirt and algae. Vitax Greenhouse Disinfectant (£3.59 500ml*) or Agralan’s Citrox (£7.99 500ml*) ideal to use for this. They contain orange oil which is not only a natural cleaner, but can smell good too. Wash any tools, pots and seed trays with the disinfectant and make sure that you wash down the inside of the greenhouse framework. This is where over wintering pests lurk, or may have deposited their eggs. Dirty pots, trays and tools harbour fungal spores which can cause damping off: death of seedlings soon after germination.
The ready-to use spray Vitax Summer Cloud Greenhouse cleaner is perfect for cleaning the glass. Here too algae and fungal spores will be lurking. Dirt blocks valuable light which will warm your greenhouse in the early months of the year. You can use this handy greenhouse cleaner to remove greenhouse sun shading too. It’s a necessity through summer, but you must remove it ready for valuable sunlight to get through in the early months of the year.
Finally it is a good idea to fumigate. Using a “smoke” pesticide means that every nook and cranny is penetrated and flying and crawling insects are killed. You can use Vitax Greenhouse Fumigator (£4.99*), or the Doff equivalent (£7.99*), whether the greenhouse is empty or you are keeping plants in there over the winter. The smoke is generated from a fumigator that you light on the greenhouse floor. You leave the greenhouse closed up for a couple of hours after use and the job is done!
Of course once your greenhouse is clean and ready for spring you could start a few hardy seeds while the weather is still cold, even if the greenhouse is unheated. Peas, broad beans and sweet peas can be sown and will have time to make excellent root systems before you harden them off and plant them out. Start them off in fibre pots like Vitax Vitapots (£2.49*). They encourage root growth and there is no disturbance when you plant them out because you plant them in the pots which just biodegrade in the soil.
One word of warning: newly sown peas and beans are vulnerable in greenhouses. Mice may also have taken refuge from the cold and your newly planted seeds will be a welcome meal. A pre-baited trap where the bait is protected from wet as well as little people playing with the bait are safest to use all round. Just tuck one in under the staging.
Protecting too against slugs and snails from the outset is a must. Although the greenhouse may start the season free of them, you only need one or two to cause a major problem. As you can shut the door to keep birds and pets out, even the most reluctant slug pellet user can be confident in sprinkling a few pellets around the edge, under the staging or at the base of walls or glass. Any ferric phosphate based pellet such as Bayer Slug Killer 700g (£6.99 or 2 for £12*) or Vitax Slug Rid is nature-friendly pellet approved by organic gardeners. In a greenhouse it is always best to prevent rather than cure, so do not wait until you have a problem before you take action.
*all prices correct at time of writing
Content courtesy of Vitax Garden World