How Frost Affects Plants & Tips for Preventing Frostburn
Updated: Sep 3
Updated by Tammy 21st May 2025
Frosts are among the greatest adversaries for gardeners throughout the colder months. Days with clear, sunny skies often lead to subzero temperatures overnight, causing frosts to occur. Without being pro-active and having measures in place, the results can be detrimental.
So, what happens to our plants when they're exposed to frost?
When our plants are exposed to frost, this is what happens:
1.Plant Tissues Freeze: The sub-zero temperatures cause the water within the plant cells to freeze.
2. Cell Damage: The cell walls and membranes of the plant then become physically damaged due to the formation of ice crystals within those cells.
3. Disruption of Cell Functions: The frozen water expands causing the cells to burst. Once this happens, the cells cease to function as they should.
4. Dehydration: As the plant begins to thaw out, the damaged cells can no longer retain water properly, which leads to dehydration.
5. Wilting and Discoloration: The affected parts of the plant then start to wilt, turn black, or become discoloured as a result of the frost damage.
6. Reduced Photosynthesis: Once plant tissues are damaged to that extent, they're no longer able to photosynthesize effectively, which can further weaken the plant.
7. Increased Vulnerability: A plant that survives frost burn will often be more vulnerable to diseases, pests, and other environmental stresses.
Tips for Preventing Frostburn
Vigilance
Watch and listen to the daily weather forecasts. Pay attention to the predicted minimum and maximum temperatures for the proceeding day. Be prepared to cover your vulnerable plants that night when sub-zero temperatures are forecast.
Cover up
Cover them up.
Check out the image below. My Seedlings at work, every night I 'tuck them in😁'
It takes me no more than a couple of minutes to roll some 'Frost cloth' out over them.
Frost cloth is a re-usable product for covering plants that still allows them to breathe, while insulating them and preventing frost from settling on them.
You'll find frost cloth at most major leading outlets and online.
An alternative to frost cloth might be an old sheet or a tarp supported by some sticks or hardwood stakes. You could even cover your plants with old plastic two litre milk containers or icecream containers. Be creative and utilise anything you've got to be able to cover them.
Location
Consider where you plant your seedlings or plants. Is there an alternative location in your yard that's more sheltered and protected, less exposed to frosts? Perhaps beneath some large established evergreen trees.
Make them mobile
You might be someone who doesn't have the option of planting out into the garden.
For renters, or perhaps elderly who find it's physically challenging to get down on the ground to garden, it might be an option for you to have your plants in large mobile planters, raised beds, or pots on wheels or caddies.
Making your plants mobile gives you the convenience of being able to move them around to expose them to sun throughout the day, then move them back under shelter at night.
Protectant
Treating your plants with a frost and sunburn protectant is another option particularly advantageous for larger vulnerable plants that it's less practical to cover.
Look for the product called 'Envy'.
Envy has been formulated by an Australian company based in Qld called Agrobest.
The product is designed to protect plants from ALL environmental climatic stresses.
The active ingredient is a water-based polymer that's non-toxic, pH neutral and biodegradable.
When it's applied to your plants it covers the foliage with an invisible membrane, protecting them from frosts, sunburn, windburn, and wilting from excessive moisture loss.
It doesn't prevent them from being able to photosynthesize and breathe (take in carbon dioxide and release oxygen).
You can find the product online through The Garden Super Store based in QLD.
Here's a link to their website Garden Shop | 1000's Of Products | The Garden Superstore
Timing of pruning
As with our roses, some plants are better off NOT to be pruned too heavily until the time of the season, when the risk of frosts has lessened.
Most plants in general will slow down with their growth over the colder months, when the days lengths are shorter, and there is less sunshine and warmth.
Pruning and feeding some plants too soon prior to Spring may encourage a flush of fresh new growth leaving in vulnerable frosts.
Gardening is so rewarding, in more ways than I can mention, but it can be costly too.
When it comes to some of the unexpected nasty frosts we often have here in our region, it's worth going that extra mile to implement a few measures to safeguard your plants, ensuring their health and survival.
By taking proactive steps such as following the weather forecasts, covering your plants, and considering you planting location options, you can minimize the risks associated with frost damage and promote the longevity of your garden. Remember, prevention is key in preventing frostburn!
Happy Gardening😘🪴
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