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Do fruit trees and frost go together? The question of frost is often on people’s minds as they’re trying to decide which fruit trees to plant in their garden. We’ve had the first few frosty mornings here on the farm, so it’s a good time to clarify the question.

The first thing to know is that winter frosts are not a problem for fruit trees.

In fact, most deciduous fruit trees need a certain predetermined number of hours of cold each year to help them set fruit. This is called the chill factor and is a separate issue from frost. You can find out more about both chill factor and frost in this online short course).

When is frost a problem for your fruit trees?

Frost is only a problem for your trees in spring. Even then, the potential problem only occurs if there’s a frost when the trees are actually flowering, or when the fruit is tiny just after flowering.

Just because there’s a frost, doesn’t necessarily mean your trees will be damaged. Your crop might be affected, but it might not!

However it’s certainly true that some fruit trees are more likely to be damaged by frosts than others. The hierarchy of frost-sensitive fruit trees is:

• almonds and apricots are most frost-sensitive, then
• cherries,
• peaches and nectarines,
• apples,
• plums, and
• pears.

How do you know if your fruit trees have been frost damaged?

Just because apples, plums, and pears are at the bottom of the list doesn’t mean they can’t get frost damage. They most definitely can.

This is a photo of a typical ‘frost ring’ on an apple – damage caused by a frost when the tree was flowering.

Another type of frost damage you’re likely to see on your fruit trees is damaged leaves. This can be one of the many reasons that leaves turn yellow (as discussed in this blog), but they’ll usually turn black and may look burnt.

You may also see frost-burned blossom. Mild damage will usually cause brown margins (as you can see below). More serious damage will look darker and more of the flowers will be affected. Unfortunately, they’ll probably shrivel up and fall off.

If you get bad frosts and don’t have a way to protect your fruit trees in spring, there’s a good chance you’ll have trouble growing apricots. That’s because they flower early and are susceptible, so the flowers will be burnt off by the frost.

This is actually one of the reasons why apricot trees are often so big. If they lose their crop to frost, they then put all their energy into growing wood instead of fruit. You can end up with a very large tree!

Protecting your trees

First, it’s important to know how frosty your place is. Where are the most vulnerable spots?

The next time you have a frosty morning, head outside nice and early in the dressing gown and gumboots. Have a really look at exactly where the frost is lying.

Then, try to match the trees you’d like to grow to the available micro-climates. Save the least frost-affected spots for the most frost-vulnerable trees.

Next, think about how you can create or enhance the microclimates. You can do this with plantings or infrastructure to create protected pockets.

Other things you can do include:

1. Planting the most sensitive fruit trees in pots so you can shift them to protected spots in spring;
2. Use frost cloth (or even old sheets) when frost is threatened (but remember to take it off again the next morning).

There’s actually quite a lot of options available to you. It’s really surprising just how much you can do to provide the right habitat for lots of different fruit trees, even if they’re a bit outside their normal comfort zone.

This avocado tree is a great example. It’s absolutely thriving in a climate that is supposedly too cold. It’s been planted in a purpose-built north-facing suntrap, and it’s worked a treat.