How To Protect Your Fruit Trees From Late-spring Frosts
A Chilly Lesson From My Garden Shed
I’ll never forget the morning I lost my cherry crop to a sneaky frost. It was mid-May. I’d just bragged to a neighbour that my Stella cherry tree had never looked better—blossoms everywhere, bees buzzing, and the faintest hint of fruit setting in. I felt like a proud parent.
Then came that cold, clear night. I didn’t check the forecast. I didn’t throw a fleece over the tree. I didn’t even glance out the window.
By breakfast, the flowers were brown and limp. That sickly, singed look you only get from frost. No cherries that year. Just a bruised ego and a few good lessons.
Since then, I’ve kept a close eye on the weather, and I’ve helped dozens of clients across London do the same. Frost in late spring doesn’t care how hard you’ve worked all winter. One cold snap and your fruit dreams can vanish overnight. But it doesn’t have to be that way.
This guide will walk you through the why, where, when, and how of frost protection. Whether you’ve got a small tree in a pot or a row of plums down the allotment, you’ll find something useful here.
Why Late-spring Frosts Are So Damaging
Understanding the Critical Growth Stages
Fruit trees are hardy in winter. When they’re dormant, they can handle freezing temperatures with ease. But spring is a different story. As soon as buds start to swell and blossoms appear, trees lose their cold resistance.
Each stage of development is more delicate than the last. Buds can survive light frost. Blossoms, however, are extremely sensitive. Just one chilly night below -2°C can destroy them. And young fruit, still soft and forming, is no tougher.
This is why that one rogue frost in April or May does far more damage than anything in December or January.
Why It’s Worse in Spring Than in Winter
In winter, trees are asleep. Their tissues are protected. Come spring, they wake up—and with that comes risk.
Spring frosts follow warm spells. The tree thinks the coast is clear and starts to grow. Then the cold hits, catching it off guard. It’s not just the flowers either. Leaves, twigs, and even developing wood can be affected if the frost is strong enough.
Know Your Frost Risk – Garden Geography Matters
Frost Pockets – Is Your Garden a Trap?
Cold air behaves like water. It flows downhill and pools in low spots. If your garden sits in a dip or is surrounded by walls or fences, it might trap cold air overnight.
This is what we call a frost pocket. You might notice frost on your lawn when your neighbour’s a few doors down have none. That’s the microclimate effect.
If you’re keen, try dusting flour across your garden at dusk before a predicted frost. In the morning, you’ll see where it settled thickest—that’s your coldest zone.
London Isn’t Immune – Urban Myths About the “Heat Island”
London’s famous for being a few degrees warmer than the countryside. But don’t let that fool you. I’ve seen apple blossoms freeze in Camden and fig buds shrivel in Lewisham.
In 2023, I worked on an apricot tree in Chiswick. Beautiful spot, well protected, right up against a brick wall. Still, a freak frost in early May burned off every single flower. The client had never seen it happen before. Neither had I—in that spot.
So yes, cities are warmer, but local frost pockets still happen.
Keep Records – A Gardener’s Frost Diary
If you’ve had frost hit you once in May, it can hit you again. Keep a simple log—dates, temperatures, tree stages, what survived, what didn’t.
It doesn’t have to be fancy. A notebook in the shed or a note on your phone will do. You’ll start spotting patterns. That’s half the battle won.
Timing Is Everything – How To Predict a Late Frost
Reading the Weather Like an Arborist
Frost doesn’t usually announce itself. But there are warning signs.
If the day’s been warm, the sky is clear, and the wind drops—brace yourself. That’s a classic setup. Warm air rises, heat escapes, and cold air settles.
Late frosts tend to strike just before dawn. That’s when the temperature hits its lowest.
Useful Tools – Forecast Apps and Thermometers
The Met Office app is a good place to start. Look for “feels like” temps, not just the air temperature. Calm, dry nights with single-digit lows are your cue.
A simple garden thermometer placed at blossom level (roughly 1–1.5 metres up) gives a better picture than anything on your phone.
The Critical Temperature Thresholds
Here’s a quick guide to damage risks:
| Fruit Type | Blossom Damage Starts At |
|---|---|
| Apples | -2°C |
| Plums | -1.5°C |
| Cherries | -2.5°C |
| Pears | -2°C |
| Peaches/Apricots | -1°C |
Protective Strategies – How To Shield Your Fruit Trees
Fleece, Sheets, and Tents – Budget-friendly Covers
Old bed sheets, horticultural fleece, even bubble wrap in a pinch—anything that traps warm air helps.
Drape it loosely so it touches the ground, creating a mini greenhouse. Use bamboo canes or stakes to stop it flattening your flowers.
Put covers on before dusk and take them off by mid-morning. You don’t want to cook the buds in late sun.
Watering for Warmth – Why Wet Soil Retains Heat
Wet soil holds heat better than dry soil. Watering the day before a frost can make a small but real difference. It works best with mulch—compost, bark, or straw keeps the warmth in.
Don’t water during a freeze. That’s counterproductive and can make things worse.
Wind Machines, Heaters, and Candles – For the Serious Grower
If you’re growing fruit commercially or just take it very seriously, there are more advanced methods.
Orchardists use paraffin candles, orchard heaters, and even wind turbines to circulate warm air. These can be adapted on a small scale with garden-safe heaters or even outdoor fairy lights (the non-LED kind—they give off a bit of heat).
But these need watching. Never leave heaters unattended.
Don’t Forget Pruning
Good pruning keeps trees healthy and balanced. It also means fewer crowded branches and more airflow—less frost damage risk.
It’s not about hacking back. Just tidy structure and removal of unnecessary growth. A well-pruned tree dries and warms faster.
What To Do If Frost Strikes Anyway
Assess the Damage
You’ll know if it’s hit. Blossoms turn black or brown. Fruitlets stop growing and drop. Leaves may look scorched.
Don’t panic. Wait a few days. Sometimes what looks dead isn’t.
Supportive Care After Frost
Don’t rush to prune frost-bitten areas. They may protect the parts underneath from a second frost. Let the damage show fully before cutting.
Keep the tree well-watered. A light feed (seaweed or balanced liquid fertiliser) can help recovery.
Hold off on any major work until you’re sure the tree’s settled again.
Secondary Blossoms – A Second Chance?
Some trees send out a second round of flowers. Apples and plums are good at this, though the crop will likely be smaller.
Bees are key. Keep an eye out for pollinators. If they’re still visiting, you’ve still got hope.
Long-term Planning – How To Future-proof Your Orchard
Choosing Late-blooming Cultivars
Some trees flower later and dodge most frosts. For apples, ‘Sunset’, ‘Fiesta’, and ‘Bramley’s Seedling’ bloom late. ‘Czar’ and ‘Blue Tit’ are good plum options.
Late bloomers may need longer summers to ripen properly, so pick what suits your patch.
Smart Placement in Your Garden
Planting near a south-facing brick wall can work wonders. Walls absorb heat during the day and release it at night.
Avoid low ground and frost pockets. Raised beds or gentle slopes help. Windbreaks from hedges or mesh can also reduce cold wind exposure.
Training Forms That Help
Fans, espaliers, and cordons give you control. You can train them along warm surfaces and prune precisely. That means fewer blossoms at risk and quicker frost recovery.
Final Thoughts From the Garden Bench
Protecting fruit trees from frost is part weather watching, part common sense, and part luck. Even the most experienced gardener gets caught out now and then—I still do.
That late frost that took my cherry tree down in 2019 was a pain. But it also taught me to respect the weather more than I did before.
Since then, I’ve covered more trees, read more forecasts, and watched more dawns than I care to admit. But I’ve also eaten a lot more fruit.
Trees bounce back. So do we. Give them the right care and attention, and they’ll reward you—maybe not this year, but the next.