Vaccinium spp

Blueberries

Origin

Varieties grown in Australia are derived from the southern USA.

Climate

A frost-free area is needed. The Southern Highbush varieties of southern USA origin require only about 200 chilling hours below 7.2°C and grow well in the Perth area. The rabbiteye varieties need 250 to 500 hours of winter chilling below 7.2°C and will crop in Perth and the South west.

Plant Description

It is an evergreen perennial shrub, up to 3m tall when grown in soil and up to 2m tall when pot-grown.

Relatives

Blueberries belong to the Ericaceae Family and are not related to other berries.

Soils

Varieties grow best on acidic soil (less than 5.2 pH), well-drained and with high organic matter. Where soils are alkaline, grow in pots with an acidic potting mixture, as used for azaleas. Increase the pot size as the plant grows.

Propagation

Propagation is difficult for home gardeners but it is possible to buy blueberries propagated from cuttings in nurseries. Blueberries have a shallow spreading root system which can produce suckers. These can be dug up and replanted elsewhere. Greenwood cuttings can be made in late spring, and hardwood cuttings in winter. Mound layering can be done in late summer or early autumn. This means cutting the bush back to two or three buds, close to the ground, then cover the whole plant with good compost. As the growing shoots come through the surface, add more compost.

After six to eight months, remove the compost; there should be roots on the stems. Cut the stems off and plant them.

Cultivars

Some Southern Highbush varieties are Misty and Sharpeblue. Burst is a newer variety being tested. The rabbiteye varieties such as Nelly Kelly have smaller, darker, fruit and are later maturing.

Flowering and Pollination

The small white to pink bell-shaped flowers are borne in winter-early spring and are pollinated by insects. Plants may be self pollinating, but cross pollination is beneficial.

Cultivation

Plant in soil in 3 to 4m rows and 0.8 to 1.0m apart. Limited pruning is needed. Weak growth should be removed. Mulch around the bushes. Good irrigation is needed, especially in summer. Good quality water is needed so use rain water if possible Use a complete NPK fertiliser when planted in soil and slow-release fertiliser for potted plants.

Wind Tolerance

Shelter from hot dry winds and place pots in semi-shaded areas in summer.

Pruning

Fruit productions begins on one-year-old wood. After the fourth year, production declines, so old canes should be pruned out. Try to cut back some stems every year, which promotes new growth and helps prevent overfruiting and biennial bearing. This will also give you bigger fruit. Bushes should be kept at a reasonable height with the centre uncongested for good air circulation. Pruning is best done in spring, when you can distinguish fruit buds from leaf buds.

The Fruit

The fruit is a berry 5–16mm in diameter with a flared crown at the end; they are pale greenish at first, then reddishpurple, and finally dark purple when ripe. They are covered in a protective coating of powdery epicuticular wax, called a “bloom”. They have a sweet taste when mature, with variable acidity. Fruits are high in antioxidants and vitamins A and C, with a low glycemic index.

Fruit Production and Harvesting

Blueberries may start bearing in the first and second years after planting. They fruit from September to December in Perth, requiring staggered picking. Fruit is mature about 7 to 14 days after it has turned blue, and a bush may produce 1 to 2 kg fruit per year.

Fruit Uses

Store at 0 to 5°C in a refrigerator. Fruit can be eaten fresh, or frozen for later dessert use. They are also used in breads, cakes, cereals, jams, jellies, muffins, pastries and pies.

Pests and Diseases

There are few problems in the Perth area, but watch out for bird damage.

Comments

Blueberries are expensive in shops, as manual labour costs for multiple harvests are high for commercial growers. Good crops can be grown in home gardens from Geraldton to the South coast.

Awareness of the human health benefits of blueberries is underpinned by a growing body of positive scientific evidence from human observational & clinical research, plus mechanistic research using animal and in vitro models. Blueberries contain a large number of phytochemicals, including abundant anthocyanin pigments. Of their various phytochemicals, anthocyanins probably make the greatest impact on blueberry health functionality. Epidemiological studies associate regular, moderate intake of blueberries and/or anthocyanins with reduced risk of cardiovascular disease, death, and type 2 diabetes, and with improved weight maintenance and neuroprotection. These findings are supported by biomarker-based evidence from human clinical studies. Among the more important healthful aspects of blueberries are their anti-inflammatory and antioxidant actions and their beneficial effects on vascular and gluco-regulatory function. Blueberry phytochemicals may affect gastrointestinal microflora & contribute to host health. These aspects have implications in degenerative diseases and conditions as well as the ageing process. More evidence, and particularly human clinical evidence, is needed to better understand the potential for anthocyanin-rich blueberries to benefit public health. However, it is widely agreed that the regular consumption of tasty, ripe blueberries can be unconditionally recommended.