Greenhouse - holding over garden plants during the winter

Wintry conditions can chill container plants to the roots, causing ill health and injury that could last well into subsequent growing seasons. Nursery and greenhouse owners, as well as homeowners, should keep this in mind when over wintering plant stock. Plants and trees that grow naturally in the soil have geothermic heat to keep their roots safe. For container plants, the plastic actually acts as a barrier and the heat is lost in the surrounding air. As a result, roots of container plants are subjected to ambient air temperature, and freezing temperatures can kill both young and mature roots.

When preparing plants for the winter, ensure they have been given a chance to reach maximum root hardiness. You can do this by waiting for plants to become dormant before covering them, avoiding covering wet plants, and using square containers for better insulation, all of which will help ensure winter survival or prevent winter injury.

Specialised plants include:

Cannas

Cannas are lifted after the foliage has been blackened by frost. Remove dead leaves and loose soil and store in trays of sand, coir or vermiculite, with the crown just showing. Keep just moist in a cold, frost-free greenhouse or conservatory. Container-grown plants can be stored in their pots.

Fuchsias

Mature fuchsias need to be kept frost-free during the winter. Remove extra foliage this reduces demands on the plant and doesn’t allow pests a chance to breed on them. It also means you can put the plants closer together, and you can see the compost surface better, helping you judge the need for watering. Prune plants back by about a third, this is usually a couple of leaf joints above the last stop. Spray or dip plants using a combined fungicide/insecticide mix. Place in cold greenhouse.