A winter frost can be such a beautiful thing—white and sparkling like tiny diamonds across the garden. But as any gardener knows, behind that beauty lies real danger for your plants. That’s why knowing how to protect plants from frost, and knowing what to do if they’re damaged is so important.
Frost doesn’t just make things chilly. It can rupture plant cells, damage roots, and even kill off healthy growth overnight. So, how do you protect your garden from frost—and what can you do if damage has already been done?
Let’s take a closer look at how to protect plants from frost.
What Does Frost Actually Do to Plants?
When temperatures drop below freezing, the water inside a plant’s cells begins to freeze. As it does, it expands—causing the cell walls to burst. This stops the plant from transporting the sap it needs to survive, and in many cases, it can cause significant or fatal damage.
There are three main types of frost:
- Ground Frost (White Frost) – Forms when the ground and surfaces dip below 0°C, creating that classic sparkling white layer.
- Hoar Frost – Similar to ground frost but forms when surfaces are already below freezing. It looks feathery and magical—but it’s still harsh on plants.
- Air Frost – This happens when the air temperature itself (a metre above ground) drops below freezing. This one can hit buds, flowers and stems particularly hard.
The most damaging frosts tend to happen in late spring, when plants are already in growth and especially vulnerable.
How to Spot Frost Damage
Frost damage isn’t always instant, but here’s what to look out for:
- Blackened or browned leaves and stems
- Wilting or limp foliage
- Flowers and buds dropping or going mushy
- Softened or discoloured fruit
- Overall drooping of above-ground growth
Hardy plants like evergreens might bounce back—but extended frosts, especially those that freeze the soil, can still take their toll.
How to Protect Your Plants from Frost
1. Plan Ahead
The best protection starts when you plan your garden. If you’re in a frost-prone area, choose hardy plants and avoid planting tender species in low-lying areas where cold air tends to settle. Avoid east-facing spots for early bloomers—the morning sun can shock frozen plants.
2. Use Natural Shelter
Plant vulnerable plants near walls, fences, shrubs or under trees to protect them from wind chill. These features help trap warmth and provide a buffer against temperature drops.
3. Leave Old Growth
Tempting as it is to cut everything back in autumn, leaving dead foliage in place can help insulate the crown of the plant. Pruning too early can expose new growth to frost.
4. Mulch Generously
Apply a thick layer (4 inches or more) of composted mulch over your borders to insulate soil and roots. This prevents the ground from freezing and protects perennials and evergreens alike.
👉 Why composted mulch is better than chipped or shredded mulch
5. Fleece & Covers
Use horticultural fleece, old sheets, or even bubble wrap to cover tender plants during cold nights. Add a layer of straw or leaves underneath for extra insulation.
Need a quick fix? Upturned buckets or bins will do the job in a pinch—just remember to uncover them during the day.
6. Pot Protection
Make sure pots are frostproof and raised on feet to avoid freezing to the ground. Line them with hessian or bubble wrap to insulate roots and stop pots cracking from cold.
7. Wrap Tender Plants
Protect plants like cordylines, tree ferns, and palms by wrapping the crown and trunk in layers of fleece stuffed with straw. It’s not the prettiest look—but it could save the plant.
8. Keep the Greenhouse in Check
Greenhouses are great frost buffers, but don’t forget them! Ventilate on warmer days and clean the glass with a fungicidal wash before spring to prevent mould.
For a deeper dive, check out this excellent guide to frost-proof pots by Andy McIndoe.
What to Do If Your Plants Are Frost Damaged
Don’t panic—many plants can recover if you give them a helping hand.
- Wait until spring before pruning—cut back damaged growth once all chance of frost has passed.
- Apply a liquid feed, such as comfrey tea, to encourage new growth.
- Move smaller plants into a greenhouse or sheltered spot to help them recover.
- Avoid overwatering—damaged plants are more susceptible to rot.
With a bit of care and patience, you may be surprised at how resilient your plants can be.
Got a Frost Tip to Share?
At Cowen Landscapes, we’ve worked through many a frosty morning—and we know every garden is a little different. If you’ve got a clever way to beat the freeze, we’d love to hear it. Or if you’d prefer a hand keeping your garden protected through winter, you know where we are.
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