Use an unheated greenhouse wisely in winter

Measure conditions instead of guessing

Use a minimum–maximum thermometer to learn how cold the space becomes overnight. Temperatures can be very different from those experienced outdoors during the day. Check doors, panes, rainwater drainage and any damaged fittings before the colder period. A greenhouse label alone cannot tell you whether tender plants will survive a particular night.

Choose suitable winter tasks

Hardy winter crops may be possible in a suitable unheated structure, depending on the plant and actual local temperatures. Alternatively, use clear space to prepare beds or organise equipment for early sowing. Remove diseased residues rather than leaving them to accumulate where they can affect later crops.

Ventilate when temperatures rise

Sunshine can raise temperatures sharply even on a chilly day. Monitor the greenhouse and ventilate when needed, balancing cooling with protection of the crop. Keeping everything shut for long periods can increase humidity and make fungal problems more likely.

Manage moisture and extra protection

Water according to the crop's needs and the state of the substrate, not a summer timetable. A second layer of fleece over appropriate hardy plants can reduce temperature swings, but it does not guarantee frost protection. Check the leaves and soil underneath rather than assuming more covers always solve the problem.

Use heating only where suitable

If additional heat is considered, equipment must be rated for the location and operated under the manufacturer's safety instructions. The safer starting point for an unheated greenhouse is to choose plants and uses that fit the temperatures it really reaches.

Keep the advice in context

These practical recommendations follow the German Gartenjahr guide. They are not fixed dates or guarantees: climate, soil, plant variety and local weather conditions all affect the best decision. Check original plant information and your own growing conditions before acting.

Read the corresponding detailed German article.