Care & Cultivation
19. Care and Cultivation of Blueberries
What to do first
After unpacking, inspect the root-balls and, if at all dry, stand the plants in a suitable depth of rainwater until they are fully moist again. Plant as soon as possible but, if your chosen site is not ready or the soil is not workable, temporarily stand your plants in a cool, light but sheltered place where the roots won’t freeze. Be sure to keep them moist, again using rainwater.
Soil Preparation and Planting
Choose a sheltered area of the garden, avoiding exposed sites. Although blueberries do best in full sun, they should also fruit reasonably well in partial shade. Most importantly they are lime-haters and require a strongly acid soil to thrive. The ground should also be free-draining but moisture retentive. Soils overlying chalk or limestone or which contain free lime will not grow these fruits and, if you have such a soil, they should be grown in containers (see below).
On suitably acid soils dig a 90cm (3ft) square hole at each planting site, removing the topsoil and mixing it with an equal quantity of acid moss peat. If your soil is heavy, add to this mix a generous quantity of lime-free sharp sand or grit. Be sure to remove any perennial weeds from the area at this time.
Plant the bushes 1.5m (5ft) apart, refilling the holes with the soil/peat mix and setting each plant with the top of the root-ball at about or slightly below soil level. After planting tread the soil around the plants thoroughly to firm them in and, when this is complete, water well with rainwater and apply a generous mulch of partly rotted sawdust, shredded bark or moss peat.
Blueberries establish and grow much better if they are not allowed to fruit in their first 1-2 seasons and this is most easily accomplished by rubbing out any fat fruit buds during the winter. The bushes will also benefit from annual renewal of the mulch of partly rotted sawdust, bark or moss peat. Do this every spring while the soil is still moist from winter rain. Each year in March apply a lime-free compound fertiliser at the manufacturers recommended rates. An additional 17g m2 (½ oz yd2) of sulphate of ammonia can also be applied if growth is not very strong and new shoots grow to less than 30cm (12in) in a full season.
Blueberries should never be allowed to go short of moisture and during dry spells should be watered regularly. Always use rainwater if at all possible but, if this runs out, it is better to use tap water than to let them dry out. Like many other soft fruits, blueberries are vulnerable to damage by birds. If your bushes cannot be included in a permanent fruit cage, the ripening crop will need to be protected by covering them with bird-proof netting.
Blueberries are ready for picking when they are blue-black, soft and detach easily from their stalks. As they don’t all ripen together it is usual to go over the bushes several times at about 4-5 day intervals.
In the first two winters remove any diseased or damaged shoots and any weak shoots lying on the ground. In subsequent years treat similarly to blackcurrants, additionally removing some of the oldest branches (about 1 in 5 of the total) cutting them back to the ground or to a vigorous new shoot close to the ground.
Growing in Containers
In the many areas where the soil is insufficiently acid to raise these fruits they are readily grown in containers. Select containers of a size that will allow plenty of room for growth and pot plants individually using an ericaceous compost or pure moss peat. In subsequent years re-pot in late autumn or early spring, as necessary, moving them on to larger containers as they grow. They must never be allowed to run short of water (rainwater) and it is better to err on the side of over-watering rather than to risk them drying out.
When plants are in full growth, feed regularly with an ericaceous liquid feed at manufacturers recommended rates. Blueberries make particularly attractive container plants on account of their autumn colour as well as their fruits and flowers.