How to care for fruit trees in winter (2024)

Much like us, deciduous fruit trees, such as peaches, nectarines and pears, take some time to rest during winter. This makes the cooler months the perfect time to treat them with protective sprays and washes.

Since the late 19th century, when Professor Pierre-Marie-Alexis Millardet discovered that copper can be used to destroy fungal spores on plants, gardeners have been using a mix of copper sulphate, lime and water known as Bordeaux mixture, to control pests and diseases in their gardens during winter.

This powerhouse plant spray is great at destroying spores that often lie in wait for warmer conditions. It’s also suitable for organic gardens and farms, making it a great alternative to store-bought sprays.

But before you get spraying, here’s everything you need to do to prep your fruit trees, as well as a simple step-by-step guide to concocting your very own Bordeaux mixture.

1. Do an annual clean-up

Before applying copper or lime, the first step in protecting fruit crops from both pests and diseases is to clean up.

Old leaves and fruit may harbour hidden overwintering eggs or spores from pests or diseases. By collecting spoiled fruit and raking up fallen leaves from around productive plants, you’re not just making your garden look tidier, you’re also removing spores. Don’t use the fruit and leaves for mulching, as they remain a source of reinfection and reinfestation, although they can be hot composted.

If you don’t have time to make a hot compost heap, simply bury the lot in the garden by placing the fruit half a metre deep in the soil, followed by leaves in the bottom of a trench one spade deep where they can rot without spreading problems.

2. Prune your trees

When deciduous plants are leafless in winter, weak, dead, fractured or rubbing branches are readily seen and pruned off. This not only improves the look of the plant, but removes areas that are easy targets for fungi, bacteria, and pests. Make sure your pruning equipment is sharp, so wounds are clean and not ragged. To prevent the spread of any bacterial and viral disease around a garden or orchard, sterilise your equipment in between pruning each tree or shrub. To do this, dip the blades in disinfectant for 30 seconds. We recommend using tea tree oil.

Alternatively, you can make up your own disinfectant with a mixture of one part household bleach to 99 parts water. Never paint pruning wounds on trees. Wound preparations have been proven to cause more problems than they are alleged to cure. Pruning wounds will naturally heal and seal far better if left alone.

3. Give them a good wash

Many common pests and diseases are resting now, hiding unseen as eggs and spores lodged in bark and bark fissures. Reset the balance using a process known as ‘winter washing’ on all deciduous fruit trees and shrubs, from apples and figs to peaches and pomegranates. This treatment is also applied to ornamental plants such as roses and frangipani that suffer fungal problems later in the year.

Bordeaux spray and lime sulphur are commonly used winter washes. Both are very effective at controlling fungal spores along with the eggs of most pest insects and mites. Yates Lime Sulphur Concentrate is an affordable stand-out for eradicating mites and leaf curl, a rather pesky fungal disease that commonly affects peach and nectarine trees.

How do you make your own Bordeaux spray?

If you have a lot of plants to treat, making your own Bordeaux spray is an economical and effective way to protect your crop. Here’s how to do it:

1. Mix ¾ cup of builders’ lime with 2.25L of water in a plastic bucket. Do not use metal buckets as the mix reacts with metal. Stir well with a wooden or plastic spoon.

2. Take a separate plastic bucket, add ½ cup of copper sulfate, available from hardware stores or chemists, then add 2.25L of water. Thoroughly stir, then pour this mixture into the lime water, while stirring continuously. The Bordeaux spray is ready to use immediately.

3. Pour the mix into a sprayer. Wet all plant surfaces thoroughly, especially bark fissures. Bordeaux spray (and lime sulphur) settles, so shake the sprayer every now and then.

4. Wash off any spray that splashes onto turf or other foliage using fresh water. Thoroughly clean out sprayers with warm soapy water, paying particular attention to nozzles.

5. Bordeaux spray and lime sulphur burn leaves, which is why they must be applied during winter dormancy before flower buds or leaves open.

How do you care for citrus trees in winter?

Although citrus are evergreen in winter, they also benefit from care at this time of the year. Established trees that have become infected with melanose disease or brown rot disease need special care.

First, remove old mulch and fallen fruit. Either hot-compost or bury this waste as it will be contaminated with disease. Apply fresh mulch around trees, making sure it doesn’t touch the trunk. Apart from cooling the soil, controlling weeds and retaining moisture, a layer of clean mulch 5cm thick helps to break the cycle of infection. Fresh mulch reduces the risk of fungal spores in infected soil being splashed by rain (or irrigation) up onto healthy citrus leaves.

Any infected citrus trees with melanose disease or brown rot disease should then be winter washed with cupric hydroxide. Make sure all parts of the citrus trees are thoroughly soaked, especially leaf undersides, bark and bark fissures.

If you have experienced trouble with stink bugs, such as bronze orange bugs or spined citrus bugs, winter is also the time to control these pests. Spray trees twice in mid-winter using horticultural oil. The oil-based spray is particularly good at smothering the nymphal stages of the bugs, dramatically reducing the number that reaches adulthood.

In warm, dry regions, water citrus regularly, especially in windy weather, but don’t feed them until after they finish flowering. Too much nitrogen encourages citrus to abort embryonic fruit, and the lush, leafy growth will only attract virus-transmitting aphids.

Should you fertilise fruit trees in winter?

When and how much you should fertilise your fruit trees depends on the maturity and type of fruit tree, but generally, fertiliser should be applied to established fruit trees towards the end of winter or early spring to support new growth coming through. Younger fruit trees will benefit from being fertilised in spring, however, you shouldn’t feed trees that have been freshly planted as they need time to set down roots and find their feet so to speak.