When I woke up yesterday morning, it was misty. We’re approaching the middle of October, which is the usual time for the first frosts of autumn in my part of the UK. People in different areas are already reporting the arrival of the frosts on Twitter. This means it’s time for me to pop out into the garden and bring in my lemon tree (which I grew from a pip, several years ago). It has been enjoying the summer weather in the garden, but it’s only really hardy down to -10°C. I’ve nearly lost it a couple of times, and it has died right back to nothing, but somehow it always manages to come back. It’s time to think about which fruit trees are truly hardy, and which will need some help.
Lemons are one of the hardiest citrus fruits, and sadly none of them are really hardy in our climate. When you’re talking about frost and fruit trees and bushes, there are really two points at which you need to worry. Now is one of them – the first frosts will kill anything tender, and damage anything not fully hardy. It’s time to bring it indoors, move it into the greenhouse, or wrap it up nice and cozy in horticultural fleece for the winter.
Of course, there are fruits that are tastier after a frost (such as sloes), fruits that are fully hardy (such as sea buckthorn) and fruit trees that need a period of cold to develop properly (apples are one such example). Plants that go dormant in the winter, which includes most top fruit and soft fruit, are generally hardy – dormancy is their way of protecting themselves. For these plants it’s not the cold that will bother them, but wind rock damaging their roots, or problems with water logging or even drought (which can be an issue when the ground freezes solid).
What is frost? Frost happens on clear nights, when the temperature drops below 0°C (32°F). Cold air sinks to the ground, flows according to the local contours, and pools in any locations it can’t escape – creating frost pockets. As you get to know your garden you’ll find out where the frost pockets are, where the cold bites deepest and which areas take the longest to warm up again during the day. You may find that strategic gaps in fences and hedges will allow the frost to flow away from your garden, or discover that removing the lower foliage from some trees and bushes will do the same thing. Learn to plant smaller fruit trees and bushes on higher ground, where they will be lifted above the frost.
The second period of the year in which you need to worry about frost damage to fruit trees is in the spring, when late frosts can kill early blossom and wipe out an entire year’s fruit crop.
Look at the hardiness rating of fruit plants, the lowest temperature to which they are hardy. Plant anything susceptible in sunnier, sheltered spots. The secret weapon in walled gardens is the walls – not only do they create shelter, but they heat up during the day and radiate that heat at night. You can recreate that effect by planting fruit trees that bloom early in spring against south-facing walls.
Dwarf trees in pots can be moved indoors temporarily, or to a more sheltered spot. Soft fruit and small plants in the ground can be protected with cloches when frost is forecast. For larger plants it’s a case of horticultural fleece or hessian sacks. However you choose to protect plants, you need to uncover them during the day so that beneficial insects can pollinate the flowers for you and ensure a good crop of fruit. It’s easier to protect fruit trees with fleece/hessian if they’re trained up a wall or a fence, and almost impossible to do for for larger trees.
For larger fruit trees, water well when frost is forecast – wet soil radiates more heat upwards into the tree than dry soil. If you can, cover soil (temporarily) in clear plastic, to trap more heat during the day. Bare soil radiates more heat too, so clear away any weeds and ground cover plants, and pull back any mulches until the risk of frost has passed.
If you live in a cold spot then look for frost-tolerant fruit varieties, cultivars that flower later in the spring and should escape the frosts, and traditional varieties that have been grown in your area for decades/centuries. All reputable fruit tree suppliers, such as Pomona Fruits, have hardiness details in their plant descriptions, and will be happy to help customers choose the right varieties for their location.
Gardeners can protect fruit trees from all but the most unexpected of frosts – the freak weather conditions that happen occasionally. To ensure a fruit harvest during those conditions, you need to take a leaf out of Carol Deppe’s book, The Resilient Gardener, and plan for diversity. If you have the space you can plant several different varieties of each fruit, which will bloom at different times, so that one or two may fruit if the others take a year off. For most of us it’s more a case of not putting all of our fruits in one basket, and ensuring a diversity of different fruit types. So if the apple/plum/pear harvest doesn’t arrive this year than it’s sad but it’s not the end of our fruit hopes, because we’ve got strawberries/raspberries/quince or even sea buckthorn to look forward to!
What’s your strategy for protecting fruit trees from frost?
This post was produced in association with Pomona Fruits, but the words are mine, as are the frosty photos. Are you feeling cold yet? Where did you leave your sweater??? 😉
This blog post was written by Emma Cooper and was published on The Unconventional Gardener website. If you're reading it elsewhere you may want to navigate away from plagiarised content.