Highbush Blueberry (Vaccinium corymbosum)

Highbush Blueberry, Smooth Highbush Blueberry

Highbush blueberry (Vaccinium corymbosum) is a type of blueberry plant native to the United States and Canada. Highbush blueberry is the most common source of commercially grown blueberries in North America. In the wild, these berries also provide a food source to small animals.

I. Appearance and Characteristics 

Vaccinium corymbosum, the northern highbush blueberry, is a North American species of blueberry which has become a food crop of significant economic importance. It is native to eastern Canada and the eastern and southern United States, from Ontario east to Nova Scotia and south as far as Florida and eastern Texas. It is also naturalized in other places: Europe, Japan, New Zealand, the Pacific Northwest of North America, etc. Other common names include blue huckleberry, tall huckleberry, swamp huckleberry, high blueberry, and swamp blueberry.

Vaccinium corymbosum is a deciduous shrub growing to 6–12 feet (1.8–3.7 m) tall and wide. It is often found in dense thickets. The dark glossy green leaves are elliptical and up to 2 inches (5 cm) long. In autumn, the leaves turn to a brilliant red, orange, yellow, and/or purple.

The flowers are long bell- or urn-shaped white to very light pink, 1⁄3 of an inch (8.5 mm) long.

The fruit is a 1⁄4-to-1⁄2-inch (6.4 to 12.7 mm) diameter blue-black berry. This plant is found in wooded or open areas with moist acidic soils.

The species is tetraploid and does not self-pollinate. Most cultivars have a chilling requirement greater than 800 hours.

Vaccinium corymbosum is the most common commercially grown blueberry in present-day North America.

It is also cultivated as an ornamental plant for home and wildlife gardens and natural landscaping projects. The pH must be very acidic (4.5 to 5.5).

II. How to Grow and Care

Sunlight

The highbush blueberry is a full sun plant. Insufficient sunlight affects its flowering and fruiting. When selecting a growing location, try to avoid placing your plants near large trees. The tree crown coverage not only affects light, but also reduces air circulation, making diseases much more likely.

Temperature

The highbush blueberry has many cultivated species that have a wide adaptability to different temperatures. However, cold temperatures (T < 7 ℃) during dormancy are vital to helping them bloom the following year. The Lowbush Blueberry and the Northern High Blueberry usually need more than 800 to 1000 chill hours in an environment below 7 ℃. The Rabbiteye highbush blueberry from the south also needs around 350 to 700 hours. It is important to pay attention to cold resistance and chill hours when selecting varieties.

The highbush blueberry has a fibrous root system with shallow root distribution. Like other Ericaceae species, its roots with symbiotic fungi absorb water and nutrients from the soil. Therefore, the highbush blueberry is neither drought-resistant nor flood-resistant, and requires careful adjustment of soil moisture.

Watering

Regular watering is needed to grow highbush blueberry. Since sandy soil it preferred has low humidity and low water retention, irrigation should be done every two or three days during a hot summer. Deep watering may be required once a week. In total, highbush blueberry require the amount of water equivalent to an average precipitation of 2.5 cm per week from germination to defoliation, and then around 4 cm from the beginning of fruit bearing to fruit harvesting. Water supply should be reduced from fall to enable the plant to enter dormancy in time.

Soil

Because the wild blueberries mostly grows on the edges of forests, they are accustomed to the acidic soil formed by dead branches and fallen leaves.Loose, acid soil (pH 3.8-5.5) with a good drainage performance and plenty of humus is best, with the optimum pH value being 4.5. Sandy soil and sandy loam are also preferred.

Soil acidity can be adjusted to cater to the highbush blueberry. If the pH of your soil is between 5.5 and 7.0, sphagnum peat can be applied at a 10 to 15 cm thickness into the 0 to 150 mm top-layer of soil, before being fully mixed in. Sphagnum peat not only improves soil acidity, but also significantly increases the content of humus. If the pH of your soil is higher than 7.0, a raised ridge bed can be built and filled with soil that has the correct acidity. Back-filling soil should be 20 to 30 cm higher than the ground plane, and all roots must be covered in the soil layer below 0 to 150 mm.

Fertilizing

The highbush blueberry is a plant that does not demand much fertilizer. However, if you are meeting soil acidity requirements and the leaves are losing their green color, or new shoots are growing extremely slowly, a nitrogen fertilizer should be considered. Ammonium nitrogen is the best kind of nitrogen fertilizer for a highbush blueberry.

After planting, young plants should be fertilized in early spring and late spring respectively. For adult plants, fertilizer can be applied every fall and winter after flowering. Each plant would benefit from an organic fertilizer or a compound fertilizer (N%-P2O5%-K2O%=15:15:15).

Excessive fertilization easily damages the highbush blueberry, and can even kill the whole plant. Forbidden fertilizer types include chlorine-containing fertilizer; nitrate nitrogen fertilizer; calcium-containing fertilizer.

Planting Instructions

  • Before planting blueberries in the ground, dig in lots of acidic organic matter, like leaf mould or composted pine needles, to improve the soil structure and drainage. Don’t use farmyard manure or mushroom compost, as these are too alkaline.
  • Space plants 1.5m apart.
  • After planting, mulch around the base of the plants with pine needles or wood chippings.
  • When planting blueberries in containers, choose a container at least 30cm (12in) in diameter, with good drainage holes. Use ericaceous soil or compost.

Pruning

Pruning of young plants: After planting, for the first two or three years, the flower buds should be completely removed in the spring. This will promote growth, improve lifespan and boost future fruit yield. Pinch off any spindly shoots during the growing season to increase the number of sprouting lateral branches, so as to expand the tree crown.

Fruiting plant pruning: From the third year after planting, the highbush blueberry should be pruned each year, before the sprouting of new buds in early spring. The annual branch bears fruits, and the stronger the branch is, the more fruits it bears. For mature plants, each cluster should retain 4 to 6 stems and 1 or 2 new branches each year, keeping the tree uniform and well-ventilated.

Because of the plant’s slow growth, pruning should be conservative. Excessive pruning will greatly affect the amount of fruits produced. Highbush blueberry has both creeping and erect branches, and the erect should be retained as much as possible when pruning.

Propagation

The highbush blueberry is best propagated through cuttings and division.

  • Cutting

Cuttings of hard branches is usually recommended for the highbush blueberries, while cuttings of tender branches is best for the rabbiteye blueberries. Both methods are acceptable for the lowbush blueberries.

Cuttings should be taken from plants that are robust and free from diseases and pests, ideally in the late spring or early summer. Annual vegetative branches with good maturity should be selected, about 20 cm long each. The rooting rate of the basal branches is significantly higher than that of the upper branches. Only take cuttings with buds, ensuring that the cut at the upper end of the branch is flat, while the cut at the lower part is oblique. Wet the soil and insert cuttings into the soil, with only one terminal bud exposed.

  • Division

Firstly, the stock plant should be dug out from the soil and its roots cleaned. Cut off the underground stem with clean sharp scissors and divide it into several plants. Fill the planting pit with a peat sand mixture with adjusted pH, then arrange the roots of the separated small plants and place them into the soil. Carefully wrap the roots with the soil mixture before filling in the hole.

Pests and Diseases

Birds

The biggest challenge when growing blueberries is stopping the birds getting to the berries before you do.

  • Cover the bushes with horticultural fleece or mesh, but only do this once the berries have started to develop or you’ll stop bees and other insects getting to the flowers to pollinate them.

Powdery mildew

Blueberries can be affected by powdery mildew, a fungal disease that looks like a white powdery deposit on leaves that can reduce the plant’s vigour. It is often a sign of drought stress, so to reduce the risk:

  • water regularly.
  • Powdery mildew is less of a problem for plants grown in cooler areas.

Frost

In very cold areas, blueberries may need winter protection.

  • Cover the bushes with fleece to protect the buds from late frosts in spring or move pot-grown plants indoors.

III. Uses and Benefits 

  • Ornamental uses

If you’re looking for a plant to attract animals to your garden, highbush blueberry is a great choice. Its flowers are mainly pollinated by bees, and birds and mammals are attracted to its fruit. This plant has ornamental appeal for its flowers and berries, and it can be grown in the borders and beds of informal and cottage gardens. This plant grows well with rhododendrons and azaleas.

  •  Culinary uses

In natural habitats, the berries are a food source for native and migrating birds, bears, and small mammals. The foliage is browsed by deer and rabbits.

The berries were collected and used in Native American cuisine in areas where Vaccinium corymbosum grew as a native plant.

IV. Harvesting and Storage

The highbush blueberry fruiting period can last for several weeks. Fruit ripens when its surface turns bluish black. Due to inconsistent ripening of fruits, they should be harvested in batches. Harvest once every 2 or 3 days in full fruit period, and once every 3 or 4 days in both the initial and final fruit period, completing your harvest before the frost.

Gloves (finger sleeves) should be worn when picking fruits to avoid damaging them, which would affect their appearance and storage potential. When picking ripe fruits, gently hold the berries and tweak them clockwise to keep the peel intact. This will also help to prolong their storage period.

Highbush Blueberry (Vaccinium corymbosum) Details

Common name Highbush Blueberry, Smooth Highbush Blueberry
Botanical name Vaccinium corymbosum
Plant type Edible
Hardiness zone 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
Growth rate Medium
Harvest time Summer
Height 6 ft. 0 in. - 12 ft. 0 in.
Width 6 ft. 0 in. - 12 ft. 0 in.
Sunlight Full sun (6 or more hours of direct sunlight a day)
Soil condition Clay
Flower color Pink
Leaf color Green