Although blueberries are grown for their fruit, they are also highly ornamental, especially in autumn when they have red and gold leaves. The blueberries most commonly grown in the UK are Northern Highbush blueberries. These bushes are hardy and require a minimum of 750 hours accumulated chilling time below 8 degrees centigrade in order to produce good yields of berries, so please do not put them into your greenhouse over the winter.
If possible, grow two or more varieties together to increase the yield of fruit and to extend the picking season. As the fruit starts to colour, try to cover the plants with bird netting to avoid your fruit being snaffled by blackbirds and the like. Plants that you buy may well be only two to three years old. These may produce a little fruit in their first year, but with patience, that trickle of berries will become an avalanche when the bushes are 5 years old plus.
Blueberries and cranberry plants can be successfully grown in the open garden, containers or raised beds where the soil is suitable for other ericaceous (acid loving) plants such as Rhododendrons, Azaleas and Heathers. The ideal soil acidity should be between pH 4.5 and 5.5, however they will tolerate soil around pH6 (pH 7 is neutral) where plenty of organic matter such as pine chippings or peat has been dug in with ericaceous compost. To keep the soil on the acid side; water on sulphate of iron as per the makers instructions in early spring and in late autumn.
Plants normally are bought in pots and can be gradually moved up a size in stages over the years until they reach 60cm (2ft) containers. Any container should have adequate drainage by way of putting crocks into the bottom of the pot and ideally be raised off the ground slightly to allow water to drain away. You should use either ericaceous compost or peat to plant your blueberry in and to help reduce the need for watering in the summer water retaining gel sachets can be added. A mulch of bark 5cm (2in) deep at least will reduce watering further. Water well after planting.
When the leaves have fully opened in late spring, the bushes will need their first feed of the season. A balanced, ericaceous, fertiliser for rhododendrons and azaleas should be used at a rate of one desertspoon per plant.The amounts used should be increased slightly over the years as the bush matures and increases in size. Repeat feeding the plant at the end of June because blueberries have a second stage of growth in late summer. Your plants' root system should be kept moist throughout the growing season, preferably using rain water as this tends to be acidic but do not get hung up if you have to use tapwater. Fertilisers used for tomatoes are not suitable as they do not contain the correct balance of nutrients. Any form of animal manure is also unsuitable for blueberries as the roots have no hairs and even well rotted manure burns the roots and may well prove fatal.
Pruning should be undertaken when the plant is dormant, usually in mid to late winter. Long canes will grow up through the bush during the summer. These give the bush its shape. Pinching out the tips of this growth will encourage a bushy plant which is the ideal. Blueberries fruit on short lateral branches grown during the spring or early summer of the previous year. Any whippy green narrow growth from the base should be removed along with anything that is damaged. All wood that has born fruit the previous year can then be taken back to the next strong, young growth. When this is complete, start tip pruning branches that have died back a little. "If in doubt, take it out!"