Highbush Blueberry

Site highbush blueberry in full sun, giving at least eight hours of summer light, in soil that is acidic, moist, well-drained and rich in organic matter; a pH near 5.0, within a workable range of about 4.5 to 5.5, suits it best, and sulfur can be worked into the bed months ahead if a soil test shows the pH running high. Space plants roughly four to five feet apart in the row, with six to eight feet between rows, and set out two- to three-year-old nursery plants rather than starting from seed. In the planting year and for a year afterward, strip off the flowers so the young shrub puts its energy into roots and shoots instead of fruit.

Watering: the root system is shallow and fibrous, largely lacking root hairs, so plants absorb water poorly and wilt readily in drought; a mulch layer over the roots and steady soil moisture, checked by feel several inches down, help guard against this, and a deep watering before winter is worthwhile if the soil has been dry.

Feeding: apply fertilizer in two split doses, half at bloom and the rest about a month later, and avoid nitrogen after early July since late growth fails to harden off properly before winter.

Pruning: young bushes need none for their first two to three years; after that, prune annually while dormant, cutting out dead or unproductive old wood at ground level. Fruit is borne on canes from two to eight years old, with five-year canes the most productive, so removing spent old canes keeps the shrub renewing itself.

Pollination: the shrub is self-fertile, but yield and berry size improve when more than one cultivar with an overlapping bloom period is planted nearby, and native bees such as bumblebees and carpenter bees are more effective pollinators of the flowers than honey bees.

Spotted wing drosophila can attack the ripening fruit, and mummy berry, a fungal disease, shrivels berries and causes them to drop before harvest. Stem blight, root rot, anthracnose, cane cankers, mildew and botrytis appear as less frequent problems, and in regions at the cold edge of the shrub's growing range, canker diseases linked to winter cold stress are more common.

Birds readily strip the ripening fruit, so netting the shrubs as berries color up is a standard defense, and deer browse the plants often enough to be a recurring nuisance. Where soil pH runs too high for the plant's acid-loving roots, leaves turn chlorotic and yellow, a sign the acidity needs correcting rather than a pest or pathogen at work.

Fruit ripens over a long window, from about June into mid-September where early, mid- and late-season plantings are combined, with berries maturing to a blue-black color under a waxy bloom. Because birds relish the ripening berries, netting the shrubs as fruit colors up protects the crop through to picking.

Culinary: the shrub is grown above all for its edible blue-black berries, eaten fresh and gathered through a harvest season that can run for months when different ripening times are combined.

Ornamental: highbush blueberry also earns a place in the garden for its small white to pale pink spring flowers, its red-tinted young stems, and fall foliage that turns shades of red, orange, purple and yellow; it is used as a hedge, in mass plantings, and in pollinator, butterfly, children's and rain gardens, where it draws native bees and other wildlife along with the birds that feed on its fruit.

Highbush blueberry descends from wild Vaccinium corymbosum populations native to eastern North America, where the species grows naturally in bogs, swamps and high-elevation forests from Maine to Minnesota and south to Florida. Cultivated forms grown for fruit were developed mainly from this wild species and the related V. australe, and highbush blueberry has become the principal blueberry type grown commercially.