Advice
RHS Help & Advice
Blueberry care
Blueberries
(Vaccinium corymbosum) require a very acid soil, (pH 4.5-5.5), which is well drained
but moisture retentive. Where this cannot be provided they
are best grown in 30-38cm (12-15in) diameter containers of ericaceous compost. Choose
a sheltered site in full sun or part shade.
Planting
Bushes for containers can be planted at any time in good growing weather, but in the ground, plant after leaf fall (November to March). Prepare soil by digging in composted bark or sawdust. Then trim off tips of branches and remove any flower buds so the plant will establish strong roots in its first year. Space bushes 1.5m (5ft) apart, although compact cultivars can be planted closer. Mulch newly-planted blueberries with composted or chipped pine bark, or leafmould if available.
For container growing, buy a bush in a 2-litre pot and check the rootball in spring every couple of years (lift plant from its pot) to see if it needs repotting. A 50-litre pot may finally be needed.
Watering
Blueberries should be watered little and often using rainwater. Do not allow to dry out even if this means resorting to tap water in dry spells. Mulch open-grown plants with bark mulch or pine needles to conserve moisture.
Feeding
After pruning, apply an acidic mulch of composted bark (or leafmould where available) and a dressing of fertiliser. Use 50g per sq m (1.5oz per sq yd) of Growmore, plus 15g per sq m (0.5oz per sq yd) sulphate of ammonia. Pelleted poultry manure is a suitable organic alternative (applied at 150g per sq m) but, as it is usually alkaline, also apply flowers of sulphur at the rate of 15g per sq m. Alternatively, apply a dressing of sulphate of ammonia, sulphate of potash and bonemeal, or apply a potash-rich or ericaceous liquid feed fortnightly during the growing season.
Pruning
The largest fruit is borne on the thicker, more vigorous shoots produced the previous spring or early summer. Strong stems that appear in late summer may also bear fruit at the tips. Pruning is carried out in late February/early March when the fruit buds are visible.
Young plants need little pruning in the first three years. Aim to produce an open centred bush, by removing horizontally growing or overly long shoots, weak stems, as well as dead or diseased wood. Prune to an upright shoot or healthy bud where possible.
On mature plants remove older stems lacking in vigour. Remove thin, twiggy stems as well as any damaged or diseased shoots, crossing or horizontal shoots a or stems close to the ground b. Cut back some branches to the base c and others to strong upright shoots. Stems that fruited the previous year should be pruned to a low, strong-growing upward-facing bud or shoot. By the end of pruning an established bush, you should have cut out roughly 15 percent of the old growth.
Pollination and fruiting
Blueberries have two flushes of growth. In spring they bear flowers on the tips of the previous-season’s growth. These flowers become the first crop of berries. New sideshoots develop just below these berries. Later, (usually in July), strong new shoots grow from the base of the plant, and produce flower and fruit buds at their tips. This second, later crop of berries is usually plumper than the first.
Blueberries benefit from cross-pollination by other varieties, which results in better fruit set. Keep plants in a sheltered spot to encourage visits from pollinating insects.
Pick fruit in stages as it ripens, protecting from birds if necessary. Ripe fruit should part easily from the cluster and will be deep mauve with a grey bloom. Each bush can provide 2-5kg (4.5-11lb) of fruit.
Cultivars
For a list of cultivars click here
More information
For more detailed advice click here
What's the difference?
Lowbush blueberries (Vaccinium angustifolium and Vaccinium myrtilloides) are low-growing wild North American blueberries. They are very hardy, with a suckering habit, and have smaller fruits with a distinctive ‘wild’ blueberry taste.
Bilberries (Vaccinium myrtillus and Vaccinium caespitosum) are native to upland moors of the UK and Europe. Low-growing suckering shrubs, they are lower yielding than the cultivated blueberries, but their fruits have a distinctive, intense flavour.
Southern highbush blueberries are hybrids bred for areas with high summer temperatures and little winter chill. They are suitable for gardens in the southern half of the UK, and for sunny, dry south-facing positions, perhaps in a sheltered courtyard. Many are evergreen. They are more drought-tolerant than other blueberries, and also more reliably self-fertile.
Cranberries (Vaccinium macrocarpon) have a trailing or groundcover habit, and are evergreen, with autumn colour and dainty flowers. They have a suckering habit and thrive in boggy peat or sand soils with a high water table. But they can make good container and hanging basket plants, when watering is attended to assiduously.
Lingonberries (Vaccinium vitis-idaea) are speciality crops in Scandinavia and the USA. They are more drought-tolerant than cranberries, similarly suckering, and have a similar but slightly less astringent taste.
Cranberries and lingonberries ripen later than blueberries, being a mid and late autumn crop, rather than a late summer and early autumn crop.
In warm climates, cranberries may not develop their characteristic red colour. However, the taste is usually unaffected, and ‘white’ cranberries are a commercially exploited crop in warmer parts of the USA.