Plants are largely made up of water, and when the temperature drops, the water in all their cells freezes, causing major problems. The cell walls are damaged and the plant often turns black and droops. Even evergreens and hardy plants can suffer when cold weather really sets in and the soil freezes. Their roots can’t get water out of the soil with the surprising result that they die from lack of water in mid-winter when the sun isn’t out.
How to prevent frost damage
Hard autumn pruning can result in new growth that then gets frost damaged, so let tender plants keep their old growth over the winter months. And be aware that high-nitrogen fertilisers can make plants put out weak, leafy growth full of sap that is very susceptible to frost damage.
Think carefully as well, about where you’re locating plants. Frost loves the hollows and dips in the garden, so avoid putting tender plants in those spots, or in east-facing positions. Put them against walls or under trees to protect them. It’s a good idea to get some advice on what will thrive where, in your particular garden. Talk to some garden experts like those at the Garden Club London who have lots of knowledge about how to realise the potential of your plot.
Remember that some types of plant are much more susceptible to damage – variegated and golden varieties can be extra sensitive. Work with the microclimate for your area and choose plants that you know can thrive – or at least survive with a bit of coddling.
Tuck tender plants in snugly
If you have very tender plants that you’re desperate to keep, horticultural fleece can be a lifesaver. You can either attach it to a frame and place it over the plants, or simply wind it around small trees or tree ferns. These plants are often better grown in pots that can be moved inside or next to a sheltered wall during the winter. Plants in pots that can’t be moved, will benefit from pot feet to help drainage.
For plants that have crowns, such as palms, bunch the leaves and tie them together, to protect the crown. Mulch will stop the soil freezing and provide moisture when the plants are having trouble finding water.
After a hard frost
If the frost does attack your plants, it won’t necessarily kill them. However, plants that haven’t long been planted may rise up out of the soil following a frost. You’ll need to firm some soil around them, and make sure the roots are covered. If small, tender plants have suffered one episode of frost damage, they may recover if you dig them up and move them to a milder environment such as the greenhouse.
When the spring (finally!) comes, cut damaged plants back to sound new buds. Give them a feed of a balanced fertiliser and you’ll soon have some healthy new growth going.