Protect your garden against frost

Not only does winter make everything look dull and lifeless, it can also cause quite a bit of damage to your garden if you are not careful. Fact is that there are ways for you to protect your garden against one of the biggest side effects of winter – frost!


According to JJ van Rensburg from Garden World frost occurs when the air particles freeze and drops to the ground. Black frost is when the temperature inside the plant cells drops so drastically that they actually cause the plant to burst open.

Cold weather, particularly frost, causes the water in plant cells to freeze, damaging the cell wall. It is clear to see which plants were damaged by frost as these plants slower (or stop growing), are blackened and distorted. Evergreen plants often turn brown and the leaves of tender plants take on a translucent appearance.

Frost problems are often made worse where plants face the morning sun, as this causes them to defrost quickly, rupturing their cell walls. Even the toughest plants can be damaged by prolonged spells of severe cold when soil becomes frozen. Roots are unable to take up water and plants die from lack of moisture.

Protecting your plants against frost

JJ says that nowadays we understand frost a lot better than many years ago. Watering a garden during winter was normally cut down to a minimal as we all believed that this would freeze the soil up, but on the contrary – water actually releases heat and if used correctly, will prevent frost bite on plants!

The other big factor is that if plant cells do not contain enough water, the negative effect of frost will increase drastically. Water during mid-morning and late afternoons, because washing away the frost will warm up and protect your plants and ensure survival. Be careful not to saturate the plants while the temperatures are extremely low, as this will result in frost heave and ultimately injure the plants.

The most common way to guard against frost is by using some type of covering. Most anything will work, but old blankets, sheets, and even burlap sacks are best.

JJ says that if you have any tropical plants you would like to cover, you can make use of frost cover or hessian. Normal frost cover is white and looks like lace – but will keep the frost off your plants. It is a synthetic thin and light material allowing air to freely move through and does not have to be removed every day. Hessian is the old common sack – brown in colour and much thicker than the frost cover – however this has to be removed daily to allow light and air movement.

Covering tender garden plants in the evening will help retain heat and protect them from freezing. When covering plants, drape them loosely and secure with stakes, rocks, or bricks. Heavier covers may require some type of support, such as wire, to prevent the plants from becoming crushed under the weight.

JJ also adds that should you stay in a valley, next to a dam or river or even where the winters are severe, you must also look at mulching the roots of your plants. By putting down a 5cm layer of straw, leaf mulch or bark you will give your plants a 'blanket' that will see the root systems through winter. Mulch helps to lock in moisture and during cold weather, holds in heat.

A garden with raised beds will also help guard plants against frost during cold temperatures. Cold air tends to collect in sunken areas rather than higher mounds. Raised beds also make covering of plants easier.

Which plants are frost sensitive?

The best way to know what type of precautionary measure you should take for tender garden plants, knows their individual needs. The more you know the better off your garden and tender plants will be.

JJ says that tropical plants, with large leaves, are usually not used to the cold. Some plants are hardier than others and those more commonly affected is Elephant Ears, Tree Ferns, Duranthas, Arums, certain Palms and Cycas.

What can I do if my plants do get frosted?

Don’t panic when this happens. Many plants will actually recover from frost damage and there are various ways to ensure that the damage is not as severe:

1. Protect damaged plants from the morning sun as it can damage the growth of the plant by defrosting it too quickly. If it is not a potted plant that can be moved around as you like, cover your plant with a black refuse bag to hide it from the sun.

2. Remove the piece of the plant that was damaged by the frost during spring time, so the plant can have the opportunity to renew itself.

3. Fertilise damaged plants with a balanced fertiliser to ensure that the plant grows healthily and strongly. The health and appearance of your garden is in your hands during winter. Make sure that you have the proper precautions in place if you want a good looking and healthy garden in spring!



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