Autumn is one of the busiest — and most rewarding — times in the Irish garden. The season’s mild temperatures and damp weather make it ideal for pruning, planting, and preparing for winter.
In this week’s Gardening Q&A, Peter Dowdall answers listeners’ most-asked questions about pruning roses and apple trees, treating rust on mallows, and what to plant instead of box hedging after Box Caterpillar damage.
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If your purple mallow (Lavatera) has orange or brown spots underneath the leaves and bumps on top, it’s likely rust, a fungal infection that thrives in warm, damp Irish conditions.
Peter’s advice:
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Remove and dispose of all fallen infected leaves, don’t compost them.
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In early spring (March–April), drench the soil around the plant with copper sulphate diluted in water to help prevent re-infection.
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Prune lightly in spring to improve air circulation through the plant’s centre.
Healthy hygiene and light pruning are usually enough to keep it under control.
When a Shrub Becomes a Tree, What to Do With Wild Willow
A listener’s wild willow (Salix) self-seeded and quickly turned from bush to tree. Peter explained that there’s no strict definition between shrub and tree, but once a willow takes hold, it grows fast and can dominate a small garden.
If removing it:
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You don’t need a tree surgeon, but you do need someone experienced with a chainsaw.
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Avoid tar, diesel, or other “old cures” they pollute and don’t stop regrowth.
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To prevent the willow coming back, you must dig out the full root system.
Before planting new trees, research the mature size, many garden problems start with trees that simply outgrow their space.
Box Hedge Dying? Try These Irish-Proof Alternatives
Box moth caterpillar has devastated box hedges across Ireland in recent years, often turning them brown within days.
Peter recommends replacing box entirely rather than trying to revive it:
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Ilex crenata (Japanese Holly) looks almost identical to box.
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Euonymus japonicus ‘Pulchellus’ compact and glossy.
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Pittosporum ‘Golf Ball’ tidy mound shape, easy to clip.
Or, for a softer look, consider low evergreen grasses or small flowering shrubs.
Always refresh the soil before planting replacements — it’s good gardening practice even if the pest won’t return.
When to Prune Roses in Ireland
Roses are hungry plants, but don’t prune them too hard yet. Peter’s advice:
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Give them a light tidy now if they’re unruly.
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Hold off on hard pruning until late February or early March.
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Mulch generously with seaweed or well-rotted manure over winter.
Because seaweed contains natural growth stimulants, mulching too early in mild weather may trigger new growth, so wait until late autumn or early winter.
Cutting Back Hydrangeas & Moving a Holly Bush
Treat hydrangeas just like roses: leave the hard prune until end of February, when frosts have passed. The dead flower heads protect the tender buds beneath, so let them act as a natural blanket over winter.
If you’re moving a young holly, December–January is the safest window. Older hollies (5 years +) don’t transplant well, so act while it’s still young.
How to Prune Apple Trees in Autumn
November is the ideal time to prune apple trees in Ireland.
Peter’s key steps:
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Remove crossing or inward-growing branches to open the crown.
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Cut out any damaged wood or areas where bark has scraped off.
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Identify the fruiting spurs, they look like short, stubby buds and keep as many as possible.
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Always aim for good air circulation to reduce disease and encourage fruiting next year.
A tidy, open-shaped tree is healthier, longer-lived, and far more productive.
Autumn gardening is about preparing, not pushing growth. By pruning at the right time, managing fungal problems, and choosing resilient alternatives to pest-affected plants, you’ll set your garden up beautifully for the year ahead.
👉 For more seasonal gardening advice, explore my Garden Design services or book an Online Consultation to plan your next season with confidence.