In the Greenhouse
The Winter Months
In winter the greenhouse need not be put to sleep. It’s a useful convalescent home for any tender plants that you may need to overwinter and even in an unheated space they will be protected from frost. Bubble wrap or horticultural fleece can also help to provide a protective micro-climate around these tender species.
Cut and come again lettuce, spinach, herb and salad leaves can also be successfully maintained in an unheated greenhouse to maintain a steady supply of fresh produce without the need for a dash to the supermarket.
If you decide to heat the greenhouse most plants and crops will be happy with a steady temperature of 2°C. Pelargoniums and less hardy species will require a higher average temperature of 5 – 7°C. There is no need to super heat the space and waste energy.
If you do use additional heating then remember to ventilate the space as increased humidity can be problematic. Use a thermometer that allows you to record maximum and minimum readings and keep a close eye on the weather for predicted temperatures and frosts.
Propagation can be undertaken in a warmer greenhouse or you could use a heated propagator to give plants an early start without wasting energy on the whole greenhouse space. Smaller propagators are available for windowsill use if you don’t have the luxury of a greenhouse.
As the days shorten you need to maximise light levels. Open blinds or remove any shading added over the summer, sterilise or disinfect any staging or fixtures to remove or reduce the threat of disease and check the heating system if you have it.
For smaller structures heating systems may not be realistic but bubble wrap can help to insulate individual plants or young seedlings. Keep an eye on the weather as first frosts can come by surprise. Inspect any plants you bring into the greenhouse for disease or virus infection and in general reduce watering levels to keep the threat of mould or mildew to a minimum.