How to Prepare Your Fruit Trees for Winter

If you grow deciduous fruit trees — peaches, plums, apples, pears, nectarines, apricots — May is the month that separates growers who get bumper harvests from those who spend spring wondering why their trees barely woke up. Autumn is your window to set the stage for next season's fruit, and most home gardeners let it slide. This guide walks you through everything your trees need right now, from feeding and pruning to pest clean-up and chill hour basics.

What you'll learn

• Why autumn feeding matters more than spring feeding for deciduous trees
• Which pruning tasks to do now versus which to leave for winter dormancy
• How to clean up fallen leaves and reduce disease carry-over
• What "chill hours" mean for SA gardeners and which regions need to worry
• A simple autumn spray programme to knock back fungal diseases before they overwinter

The South African Context

Season: Autumn — April through June
This article applies to: May, the core of SA autumn
Relevant crops: All deciduous fruit — peaches, plums, nectarines, apricots, cherries, apples, pears, quinces, pomegranates, figs, grapes

Regional differences

Highveld (Gauteng, Mpumalanga, Free State, North West plateau — ~1,500 m elevation)
May marks the end of the summer rainfall season. Days are warm and sunny but nights are cooling fast — frosts typically arrive in June. Deciduous trees are dropping leaves or well into colour change. This is prime time for all autumn tasks. Frost-sensitive evergreen fruit (citrus, avocado, mango) need protection planning by the end of May.

Western Cape (winter rainfall)
Autumn arrives here with the first rains after a dry summer. Stone fruit and pip fruit are coming out of a long hot growing season. Fungal pressure (leaf curl, brown rot) is rising as moisture returns. Timing for dormant sprays is critical here — act before prolonged wet spells.

KwaZulu-Natal and coastal regions
Milder and more humid — leaves may hold longer. Stone fruit in the midlands follow a pattern closer to the Highveld; coastal areas rarely get the cold needed for high-chill cultivars. Focus on disease clean-up and selecting the right low-chill cultivars if you're replanting.

Limpopo and Lowveld
Tropical and subtropical fruit (mango, avocado, litchi) are your main game here. Autumn is harvest season for late mangoes. Deciduous fruit is marginal in the lower Lowveld — stick to figs and pomegranates if chill hours are insufficient.

Why Autumn Feeding Is Non-Negotiable

Most home gardeners fertilise in spring when trees are flowering and everyone feels the urge to "help." But here's the thing: the energy that drives spring growth and fruit set was largely stored in the tree during autumn. Feed now, and you're loading the tank. Skip autumn, and you're asking a tree to perform on an empty stomach.

What to apply and when

Early to mid-May (before leaves fully drop):

Apply a balanced fertiliser with a slight potassium bias. Look for something in the 3:1:5 or 3:2:5 range (N:P:K). Wonder 3:1:5 is widely available from Builders Warehouse, Starke Ayres, and most garden centres. Potassium (K) hardens wood, improves cold tolerance, and supports the carbohydrate storage that fuels spring.

Application rates (per established tree, spread over the drip zone):

• Small tree (under 3 years): 200–300 g
• Medium tree (3–7 years): 300–500 g
• Large mature tree: 500 g–1 kg

Water in well after application.

Boron note for stone fruit:
Peaches and nectarines in SA soils are frequently boron-deficient, which leads to hollow stone, poor fruit set, and gummosis. A foliar boron spray in autumn (Solubor at 1 g/L) while leaves are still on helps the tree store this micro-nutrient ahead of bud set. One or two applications now will pay off at pollination time.

Avoid high-nitrogen fertilisers now. Nitrogen pushes leafy growth, which is exactly what you don't want heading into dormancy. Soft autumn growth is frost-bait and a red flag for aphid pressure in spring.

Mulching

After feeding, top up your mulch layer to 100–150 mm around the base of each tree, keeping mulch 150 mm clear of the trunk to prevent collar rot. Good mulch options available at SA nurseries and hardware stores include:

• Wood chip (from tree services or garden centres)
• Lucerne hay (expensive but excellent — pick up from agricultural co-ops)
• Straw
• Shredded kraal manure (works as both mulch and slow-release feed)

Mulch moderates soil temperature, protects roots during frost, retains moisture during dry winter months, and feeds soil biology as it breaks down.

Pruning: What to Do Now vs What to Wait For

This is probably the single biggest source of confusion for home orchardists, so let's be direct.

Do NOW (May, while leaves are still falling or recently dropped):

Dead, diseased, and damaged wood (the three D's) — Remove any branches showing:

• Gummosis (amber gooey ooze on peaches and plums — likely bacterial canker or borer damage)
• Brown rot mummies (dried, shrivelled fruit still hanging on the tree — remove and destroy, do not compost)
• Dieback from the tips inward
• Rubbing branches that are creating wounds

Tool hygiene matters here. Sterilise your secateurs and loppers with Jeyes Fluid or diluted bleach (1 part bleach : 9 parts water) between trees and between cuts on diseased wood. Bacterial canker spreads on dirty blades.

Wait for full dormancy (June–July on the Highveld, June in the Western Cape):

Structural pruning — shaping the tree, opening the canopy, removing crossing branches, shortening leaders — is best done when the tree is fully dormant and leafless. You can see the structure clearly, the tree is under minimal stress, and wounds callus well in cool dry conditions.

If you prune heavy structural cuts now while the tree is still active, you risk pushing soft autumn growth from latent buds near the cuts. That growth gets frosted, creates entry points for disease, and wastes the tree's stored energy.

The exception: Figs and pomegranates can be shaped now if needed. They're more forgiving and respond well to autumn pruning in SA conditions.

Disease Clean-Up: Your Single Most Effective Autumn Task

Walk around your orchard right now and look down. If you see a carpet of fallen leaves, you're looking at the overwintering reservoir for most of your spring fungal problems — peach leaf curl, shot hole, brown rot, and apple scab all overwinter in fallen leaf matter.

The rule is simple: remove and destroy fallen leaves. Do not compost them.

Bag them for green waste collection, burn them if permitted in your municipality (check local bylaws), or put them in a hot compost heap that genuinely reaches 60┬░C. A lazy cold heap will not kill the spores.

Autumn dormant spray programme

Once at least 80% of leaves have fallen, apply a dormant spray. This is one of the highest-return tasks in the orchard calendar.

Copper oxychloride (e.g., Cuprofix, Demildex):

• Fungicidal and bactericidal
• Targets leaf curl on peaches and nectarines, bacterial canker, brown rot
• Mix at label rate (typically 30–50 g per 10 L water)
• Apply as a thorough drenching spray covering all bark, crotches, and spurs
• Timing: After leaf fall, before bud swell (roughly May–June on the Highveld)
• Safety: Wear gloves, eye protection, and a mask. Avoid spraying in wind. Keep away from water sources — copper is toxic to fish and aquatic organisms. Follow label instructions.

Lime sulphur (available from Starke Ayres and select garden centres):

• Excellent against fungal spores and some scale insects
• Can be used as an alternative to copper or in rotation
• Do NOT mix with copper — spray on separate days
• Note: Lime sulphur smells strongly of rotten eggs. Warn your neighbours.
• Safety: Corrosive. Full PPE required — gloves, eye protection, old clothing. Rinse equipment thoroughly.

Dormant oil (e.g., Oleum, mineral oil sprays):

• Targets overwintering scale insects, red spider mite eggs, and some aphid eggs
• Often mixed with lime sulphur for a combined spray
• Apply when temperatures are above 7┬░C and below 30┬░C — avoid frost days

Apply dormant sprays on a still, dry day. If rain falls within 24 hours of application, you'll need to reapply.

Understanding Chill Hours: A Practical SA Guide

Chill hours are the number of hours that temperatures sit between 0┬░C and 7┬░C during winter dormancy. Deciduous fruit trees need a minimum number of accumulated chill hours to complete dormancy — without it, they break bud unevenly, flower poorly, and crop badly.

Highveld (Johannesburg, Pretoria, Midlands): Generally receives 400–800+ chill hours per winter. High-chill cultivars (most standard apple and pear varieties) grow well here.

Western Cape valleys (Elgin, Ceres, Villiersdorp): SA's premium stone and pip fruit region — reliably cold winters with 800–1,200+ chill hours.

Warmer areas (Lowveld, coastal KZN, Limpopo bushveld): Low chill — often under 300 hours. Stick to low-chill cultivars:

• Peaches: Flordaprince, Flordastar, Tropic Snow
• Apples: Anna, Dorsett Golden, Fuji (partially)
• Pears: Hood, Flordahome

Why this matters in May: Autumn is when you decide whether to replant a poorly performing tree. If your apple or stone fruit has been setting fruit badly for years, insufficient chill hours may be the cause — not your growing technique. Talk to your nursery (Starke Ayres or a specialist grafted tree nursery) about cultivar selection before investing in a new tree.

Tools and Materials

• Sharp, clean secateurs (Felco, Bahco, or Okatsune are available at Starke Ayres and specialist nurseries)
• Loppers for branches over 15 mm diameter
• Pruning saw for larger cuts
• Sterilising solution (Jeyes Fluid, diluted bleach)
• Sealing compound (optional but recommended for large cuts on stone fruit — Steriseal or grafting wax)
• 3:1:5 or 3:2:5 fertiliser
• Solubor (boron) for stone fruit
• Copper oxychloride fungicide
• Lime sulphur (optional)
• Dormant oil
• Knapsack or hand sprayer
• Full PPE: gloves, safety glasses, mask

Common Mistakes

1. Feeding with 2:3:2 or high-nitrogen fertiliser in autumn. This is a spring product. In autumn, you want potassium and phosphorus, not nitrogen.
2. Leaving brown rot mummies on the tree. Those dried, shrivelled fruits are ticking fungal bombs. They'll release spores directly onto your spring blossoms. Remove every single one.
3. Pruning the whole tree in May. Structural pruning done before full dormancy pushes soft growth that gets frosted. Do the disease removal now; do the shaping in June or July.
4. Skipping the dormant spray "because the tree looks healthy." Fungal and bacterial pathogens are invisible on bark. The dormant copper spray is cheap insurance — probably the best R50–R100 you'll spend in your orchard this year.
5. Mulching right up against the trunk. Mulch against bark creates the warm, moist environment that collar rot fungi love. Always leave a clear gap of 150 mm around the trunk.
6. Ignoring water in winter. The Highveld winter is dry. Your trees aren't actively growing, but roots are still alive and the soil shouldn't become completely parched. A deep water every 3–4 weeks through winter keeps roots healthy, especially for young trees under 3 years old.

Troubleshooting

Gummy amber ooze on peach trunk or branches: Likely bacterial canker or borer damage. Cut out all affected wood to clean tissue (sterilise blade between cuts), seal the wound, and apply a copper spray. Dispose of removed wood — do not compost.

Leaves with orange or rusty spots before dropping: Could be rust fungus (common on pears) or early leaf curl. Apply a copper spray while leaves are still on. Clean up all fallen leaves thoroughly.

Tree not dropping leaves properly / holding onto dry brown leaves: Common in fig and some apple varieties, or trees under stress. Not necessarily a problem, but ensure the tree isn't waterlogged and has had adequate potassium this season.

Trunk damage — paint-like peeling or discolouration near the base: Could be collar rot (Phytophthora). Improve drainage around the base, pull mulch well clear of the trunk, and consider a Phytophthora drench with Fongarid if severe.

What to Do This Week

1. Walk your orchard and collect all fallen leaves and fruit mummies. Bag or burn — do not compost.
2. Apply 3:1:5 fertiliser at the drip zone of each deciduous tree and water in.
3. Cut out all dead, diseased, and damaged wood. Sterilise secateurs between cuts.
4. Top up mulch to 100–150 mm around each tree, keeping clear of the trunk.
5. Mix and apply copper oxychloride once 80% of leaves have dropped — do it this week or next if you're on the Highveld.
6. Order or source dormant oil and lime sulphur from Starke Ayres or a garden centre while stock is good — these are seasonal products that can sell out.
7. Apply foliar boron spray (Solubor at 1 g/L) to peaches and nectarines while leaves are still present.
8. Check your citrus and avocados — plan frost protection (shade cloth, frost guard sprays) before June frosts arrive.

FAQ

When exactly should I do my dormant spray?

After at least 80% of leaves have fallen from your deciduous trees. On the Highveld this typically happens in May to early June. Don't wait until the tree looks completely bare — you don't want to delay into the coldest nights when application is harder. A dry, still day with temperatures between 10–25┬░C is ideal.

My peach tree has never had leaf curl — do I still need to spray?

Leaf curl (Taphrina deformans) spores are present in most orchards and spread easily on wind and rain. A tree that has escaped it is lucky, not immune. The dormant copper spray is cheap and low-effort — far less hassle than managing a full leaf curl outbreak in spring.

Can I prune my citrus now?

Light shaping of citrus is fine in autumn, but avoid heavy pruning before the frost risk period. Major citrus pruning is better done after the last frost in August–September, just before the spring flush. In the warmer Western Cape, light pruning can happen after harvest.

How much should I water fruit trees in winter?

On the Highveld, winter is dry but not completely rainless. For established trees (3+ years), a deep water every 3–4 weeks is sufficient if there's been no rain. For trees planted this past season, water every 2–3 weeks — their root systems aren't yet deep enough to find moisture independently.

Do I need to paint tree trunks white?

Trunk whitewashing (lime wash) is a traditional practice that reflects sunlight and prevents sunscald on the trunk during the hot-cold temperature swings of Highveld winter days and nights. It's particularly useful on young trees with thin bark. Mix agricultural lime with water to a milk consistency and paint the lower trunk. Not essential for established trees with thick bark, but no harm in doing it.

My apple didn't crop well this year. What happened?

Several possibilities: insufficient chill hours (cultivar mismatch for your region), poor pollination (lack of a compatible polliniser tree nearby), biennial bearing (the tree crops heavily every second year), or disease pressure reducing leaf area and photosynthesis. Use this autumn to diagnose and address — a local specialist nursery can help identify your cultivar and confirm if chill hours are the issue.

Summary

May is the unsung hero of the fruit tree calendar. The work you do now — feeding with the right fertiliser, cleaning up disease reservoirs, applying dormant sprays, and removing diseased wood — quietly determines whether your trees will reward you with a strong spring flush and a good crop next season. It's not glamorous work, but it's foundational.

The key things to walk away with: feed with potassium-forward fertiliser now, do disease clean-up before full dormancy, apply your copper spray after leaf fall, and save structural pruning for June and July when the tree is fully asleep. Small, consistent actions in autumn add up to the orchard you want by summer.