Autumn offers a useful window of opportunity in the greenhouse to ensure you’re prepared for winter.
Gardening expert, author and broadcaster Matthew Biggs, a regular panellist on BBC Radio 4’s Gardeners’ Question Time, offers 5 tips on greenhouse maintenance to ensure you’re ready for winter.
Greenhouse maintenance – 5 autumn greenhouse jobs
1. Sow while it’s warm
While it is still warm and sunny, sow trays, pots or old growing bags in your greenhouse with ‘cut and come again’ crops which you can harvest throughout autumn and into winter.
If you are looking for inspirational species ideas, try land cress, oriental salad leaves like pak choi, mizuna and mibuna. Or stick to classic lettuce varieties, like ‘Valdor’, chicory and radishes. You can also add brassica crops for microgreens which you can harvest earlier.
2. Grow out-of-season flowers
By providing extra warmth, plants which are normally dormant during early autumn and winter months can be ‘woken early’ and will look their best several months ahead of those grown naturally outdoors.
Some, such as hyacinths, are often available as ‘prepared’ bulbs, which means they have been treated to simulate an artificial winter and will therefore spring into growth as soon as planted. Buy quality bulbs in autumn and plant closely in pots using peat-free potting compost and keep them in cool, deep shade under the greenhouse bench until the leaves are 5cm long.
If you have a greenhouse bed and have grown summer food crops, a good autumn and winter use for the vacant space is to raise cut flowers.
Freesias can be grown for display or cutting and flower naturally in late winter and thrive in a cool greenhouse.
3. Clear up
Along with spring, autumn provides a natural opportunity to do some essential greenhouse maintenance .
Aim to clean up both the inside and outside of your greenhouse on a warm, dry autumn day. Clean the windows of your greenhouse, paying attention to the individual frames. This will let in more natural light to help your plants photosynthesise better and thrive through the colder months.
Remove moss from overlapping panes with an old kitchen knife or plant label. Use a cleaning product which is suited to your particular greenhouse’s glazing system. Taking out old leaves, dead plants and decaying moss will also help reduce the amount of bugs and pests you see. You can then compost these products to make an organic fertiliser to use on your plants.
4. Check guttering
Check your gutters are clear of leaves and clean down pipes. Scoop leaves out with your hands, wearing gloves, and flush debris away with a hosepipe or watering can. Although not the most glamorous part of greenhouse maintenance, this will help you collect more rainwater to use on your plants and help you produce the best crop.
While protecting and removing any delicate plants, clean the floor of your greenhouse and disinfect all benches, shelving and equipment.
5. Get ready for winter
Check your greenhouse heater to make sure it’s working.
There are pros and cons to insulating the greenhouse with bubble wrap in winter. For many gardeners, myself included, it’s not one of my favourite jobs.
If you do choose to do it, an important consideration is to maintain a balance between the amount of light, heat conservation and ventilation.
Full insulation reduces the amount of light coming into the greenhouse and increases humidity, which can cause disease problems. To minimise this, be sure to remember to cut holes for the ventilators.
If you live in an area where winters are usually mild, it is worth taking the gamble of not insulating at all but have a heater and protective layers on standby should the weather change. If plants need more than protection from frost, wrap them individually with fleece in the greenhouse.
For more information on greenhouse maintenance visit Hartley Botanic to read Matthew Biggs’ ‘Greenhouse Growing Month by Month’ guide, updated with tips and ideas of what to do and grow in your greenhouse.
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