Crops in Unheated Greenhouses

Many people only use their greenhouse for growing plants in the summer, and for storage (e.g. plant pots and seed trays) in the winter. But your unheated greenhouse can be used for growing crops most of the year.

An unheated greenhouse is up to 5° warmer than the temperature outside and will keep plants frost free in all but the worst of winters. So here are some tips to make the most of your greenhouse.

• Keep plants on the dry side and they are less likely to freeze. 
• Dry conditions also lessen the risk of fungal infections.
• Maintain an even temperature. Close the door and window vents in frosty or windy weather, and open on warm sunny days to prevent overheating.
• Keep plants away from contact with the glass.
• Remove summer shading to miximise light levels.
• Clean thoroughly between summer and winter use.
• Either a pile of bricks or a bucket of water in the greenhouse will absorb warmth by day and release it over night. 

What to grow? Try the following:

• Lettuce
• Basil and other herbs
• Chard and spinach beet
• Late sown carrots (no problems with carrot fly!)
• Chillies grown in summer will continue to fruit, just reduce the watering in autumn.
• Potatoes for Christmas; grow and early crop and cover with fleece on cold nights.