How do I prune a blueberry bush?

Blueberries fruit best on stems that are two to four years old, on shoots produced the previous summer. Older stems keep growing but produce progressively smaller berries on twiggier growth. The pruning method is therefore renewal, like a blackcurrant but much less aggressive: remove a small number of the oldest stems each year so the bush always has wood of every age.

What you'll need

• Secateurs
• Loppers for old thick stems (optional)

Step by step

1. Prune in late winter, February to March.While dormant and before bud break. You can see the structure and the fat rounded fruit buds at the tips of last summer's shoots, which makes the decisions obvious.
2. Learn to read the fruit buds.Fruit buds are plump and rounded and sit towards the tips of the previous summer's shoots. Leaf buds are small, slim and pointed. That tells you at a glance which wood is carrying the crop.
3. Do very little for the first three years.Remove dead, damaged, crossing and weak twiggy growth only. Let the bush build a framework of strong stems. Cutting a young blueberry back hard delays cropping for years.
4. From year four, take out one or two of the oldest stems each winter.The thickest, greyest, most branched ones with the smallest twiggy growth. Cut them right down at the base, or to a strong low young shoot.
5. Remove low branches trailing on the ground.The fruit on them sits in the soil, rots, and is easy pickings for slugs.
6. Thin out very twiggy growth at the tips.Congested twiggy shoot systems carry many small berries. Removing some of them concentrates the crop into fewer, larger fruit.
7. Leave the strong young shoots alone.Whip-like shoots produced from the base last summer are the future of the bush. Do not shorten them.
8. Renovate a neglected bush over two or three winters.Take out a third of the oldest stems each year rather than cutting the whole plant down. Cutting it all to the ground removes several years of cropping.
9. Feed and mulch afterwards.Ericaceous feed in spring, plus a mulch of pine needles, composted bark or ericaceous compost. Never lime, never general fertiliser.

Tips

• Blueberries in pots need the same treatment plus a compost refresh, so combine pruning with top-dressing or repotting.
• The fat rounded fruit buds are easy to see in February. If you are unsure which stems matter, look at where those buds are and keep that wood.
• Blueberries flower quite early and can be frosted in an exposed garden. Being in a pot means the plant can be moved somewhere sheltered for a cold night.
• A blueberry can be left almost entirely unpruned for years and will still crop, just with progressively smaller berries. Renewal pruning is about quality more than survival.

Common mistakes

• Pruning a young bush hard 'to shape it' — It removes the wood that would have carried the first crops and delays real production by years. Under four years old, remove almost nothing.
• Shortening the strong young shoots — Those carry the fat fruit buds near their tips. Cutting them removes the crop.
• Cutting an old bush to the ground in one go — It loses two or three years of fruit. Renovate a third at a time.
• Using ordinary fertiliser or garden compost as a mulch — Both raise the pH. Blueberries need ericaceous feed and acidic mulches — pine needles, composted bark or ericaceous compost.

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