Blueberries are perennial flowering plants with blue– or purple–colored berries. They are classified in the section Cyanococcus within the genus Vaccinium. Vaccinium also includes cranberries, bilberries, huckleberries and Madeira blueberries.
Commercial “blueberries” – including both wild (‘lowbush’) and cultivated (‘highbush’) blueberries – are all native to North America. The highbush blueberry varieties were introduced into Europe during the 1930s.
Blueberries are usually prostrate shrubs that can vary in size from 10 centimeters (3.9 in) to 4 meters (13 ft.) in height. In commercial production of blueberries, the species with small, pea–size berries growing on low–level bushes are known as “lowbush blueberries” (synonymous with “wild”), while the species with larger berries growing on taller cultivated bushes are known as “highbush blueberries”.
The leaves can be either deciduous or evergreen, ovate to lanceolate, and 1–8 cm (0.39–3.15 in) long and 0.5–3.5 cm (0.20–1.38 in) broad. The flowers are bell-shaped, white, pale pink or red, sometimes tinged greenish. The fruit is a berry 5–16 millimeters (0.20–0.63 in) in diameter with a flared crown at the end; they are pale greenish at first, then reddish-purple, and finally dark purple when ripe. They are covered in a protective coating of powdery epicuticular wax, colloquially known as the “bloom”.
They have a sweet taste when mature, with variable acidity. Blueberry bushes typically bear fruit in the middle of the growing season: fruiting times are affected by local conditions such as altitude and latitude, so the peak of the crop.
Blueberry plants can be planted as close as 60cm apart which will form a thick hedge after a couple of years, but in general most fields are planted using a plant spacing of 0.9m to 1.2m between plants with spacing between rows of 1.8m to 2.8m which would result in a plant density of 3000 to 6200 plants per hectare.
The distances between the rows will depend on which equipment will be used for cultivation, harvesting and pruning. With smaller scale operations hand harvesting is normally used where the row spacing’s are narrower. Most blueberry farmers plant about 6000 plants per Ha, but some who use 25L to 28L pots or grow-bags plant up to 8500 plants per Ha for optimum production.
Northern highbush blueberry varieties are the most common types of blueberries cultivated throughout the world. Highbush blueberry varieties are more disease resistant than other blueberry varieties