Fight Back Against Frost

When temperatures drop to 0°C or lower, we like to bundle up inside with a blanket or around a fire to keep us warm. Unfortunately, the plants in our garden don’t have that luxury. They have to brave the elements and face possible serious damage in the process.

How frost affects plants

A layer of white ice crystals covering your garden is a worrying sign, especially when it is prolonged. But frost doesn’t only affect the outside appearance of your plants. Ice crystals can also do damage at a cellular level, killing off parts of the plant or potentially the entire plant if not protected.

Ice crystals that form outside of the plant’s cells can cause dehydration and damage to the cell walls. This damage causes cell membranes to rupture, impacting important cellular processes that keep the plant alive. Frost also forms inside the plant’s cells. When ice forms inside the cell, it can expand and burst, leading to cell death. The formation of ice crystals inside the cell also reduces levels of important compounds like amino acids and sugars that are essential to plant survival.

Some plants are obviously more sensitive to frost than others, depending on the conditions in their native environments. Younger plants are also more vulnerable to damage than mature, established plants, especially if the frost persists for long periods.

Although frost may be evident on your plants during temperature dips, the damage caused could only begin to show days later. Leaves and stems may become discoloured and soft, with some changes in shape as a result of the cell damage. Plants will likely stop growing or may drop their leaves if the problem is severe.

Black Frost

Black frost is an even more troubling type of frost that occurs when temperatures drop rapidly in dry conditions. The damage caused by black frost can be more subtle and insidious, as the freezing temperatures cause water in the plant cells to freeze and expand, leading to cell rupture and death without any visible frost coating on the plants at all. You’ll likely only notice the problem when your plants begin to turn black and die off – hence the name ‘black’ frost.

Protecting Plants From Frost

If you live in a region prone to frost, protecting your plants should be top of mind during the cooler months. Choosing frost-hardy plants is the first step, but if you’re growing some plants that are more vulnerable, there are a few ways to keep them warm.

READ MORE: How to prepare for frost!

Frost Blankets

Frost protection fabric like Frost Gard is the first thing many gardeners reach for. These fabrics are simply draped over beds or individual plants when frost is suspected, keeping them safe from damage. As an added bonus, these covers can also stop birds and certain bugs from reaching your plants, especially useful in edible gardens.

TIPS:
1. Make sure the frost blanket is securely anchored around the edges to prevent wind from blowing it away. Use rocks, bricks, or other heavy objects to hold the blanket in place.
2. Ensure that the frost blanket completely covers the plant, all the way to the ground, and double up if the temperatures are dropping significantly. If there are gaps, cold air can get in and damage the plant.

Mulching

Make sure the frost blanket is securely anchored around the edges to prevent wind from blowing it away. Use rocks, bricks, or other heavy objects to hold the blanket in place.Ensure that the frost blanket completely covers the plant, all the way to the ground, and double up if the temperatures are dropping significantly. If there are gaps, cold air can get in and damage the plant.

Cutting Back

Part of your regular pruning schedule should include cutting some plants back before frost to protect them from damage. Soft perennials like begonias and impatiens benefit from a trim to limit potential damage to vulnerable foliage. After cutting back, cover the base with a thick layer of mulch to protect the roots. New growth will pop up again when temperatures rise, coming back strong.

Move Your Pots

Plants in containers have the benefit of portability, allowing you to simply move them to a spot where they won’t be impacted if frost is suspected. This is why it’s helpful to plant, especially sensitive plants, in containers if you live in a frosty area, helping you prepare for the winter months without hassle. Move your containers into a greenhouse where they can be protected, or even indoors until frost risk subsides. Try to keep conditions like sunlight and watering as consistent as possible to limit stress from changing environments. If your larger pots are heavy, enlist some help or keep them on wheels to make moving a breeze.

DIY Cloches

Smaller plants can be protected from problems with the help of DIY cloches made from plastic bottles. Although limited in size, these cloches are so easy to make that you can have several on hand for individual plants in your beds. Cut the bottom off a large plastic bottle and place it over your plant like a mini greenhouse. The plastic will protect the plant from frost, while the bottle’s narrow opening will allow for air circulation.

Wrap Trees

Newly planted trees are far more vulnerable to frost damage than established ones. It’s vital to avoid damage during this crucial stage of growth, particularly for fruiting trees you plant to harvest from later on. To protect young trees in autumn and winter, wrap the branches with hessian or another insulating material when frost risk is high. Although trees can recover from light frost damage quite well, it’s always better to avoid the damage altogether to keep your trees as healthy as possible.

Finally, if you want to avoid this added maintenance year after year, stick to plants that will better survive the winter in your climate or plant in a protected area. That way, even if there is frost on the way, you can stay bundled up inside without worrying about your garden all season long.

READ MORE: Fighting frost while still having a beautiful garden