Blueberries are small, round, and nutrient-rich berries known for their vibrant blue color and sweet-tart flavor packed with antioxidants like anthocyanins. Blueberry farming has gained popularity worldwide due to the fruit’s high demand for its health benefits and versatility. With proper soil conditions, climate, and cultivation practices, growing blueberries can be a rewarding venture for both commercial and small-scale farmers. These versatile berries can be enjoyed fresh, frozen, or dried, and are commonly used in smoothies, baked goods, salads, or as a healthy snack. Complete detail
Classification
Kingdom : Plantae (Plants)
Subkingdom : Tracheobionta (Vascular plants)
Superdivision : Spermatophyta (Seed plants)
Division : Magnoliophyta (Flowering plants)
Class : Magnoliopsida (Dicotyledons)
Subclass : Dilleniidae
Order : Ericales
Family : Ericaceae
Genus : Vaccinium
Species : Corymbosum, angustifolium, ashei
Commercial Blueberry Varieties
Highbush blueberry (Vaccinium corymbosum)
Highbush blueberry, also known as the northern highbush, is the most widely cultivated variety of blueberry. Native to North America, these plants typically grow to a height of 4 to 6 feet and thrive in sunny, acidic, and swampy areas. Their adaptability and productivity make them a popular choice for commercial and home gardening alike.
Lowbush blueberry (V. angustifolium and V. myrtilloides)
The lowbush blueberry is a compact variety native to North America, growing to a height of less than 3 feet. Known for its sweet flavor, it produces the smallest berries among blueberry types, which are also prized for their exceptionally high antioxidant levels. Improved lowbush cultivars are available, making this variety a popular choice for its nutritional benefits and suitability for various growing conditions.
Rabbiteye blueberry (V. ashei)
The rabbiteye blueberry is native to southern Georgia and northern Florida in the United States, where it thrives in river bottoms and swampy, acidic soils. This variety is larger and more vigorous than the highbush blueberry, with a lower chilling requirement, making it ideal for warmer regions. Its fruit is notable for its thick skin and a large bottom or sepal scar, distinguishing it from other blueberry types.
Southern Highbush
The southern highbush blueberry is a hybrid developed from Vaccinium corymbosum crossed with V. darrowi, V. ashei, and other southern Vaccinium species. With the inclusion of the low-chilling V. darrowi in its parentage, this variety is specifically designed for regions with mild winters, offering a shorter fruit development period and early maturity. While similar to the northern highbush in many aspects, the southern highbush stands out for its adaptability to warmer climates.
Halfhigh bluberry (V. Corymbosum X V. Angustifolium)
The half-high blueberry is a hybrid resulting from crosses or backcrosses between lowbush and highbush varieties. A recent innovation from breeding programs combines traits from both parent types, growing to an intermediate height of 2 to 4 feet. The plant produces fruit similar to highbush varieties but is exceptionally cold hardy, making it well-suited for extreme winters and areas with heavy snow loads.
Soil Requirement
Blueberries thrive in acidic soil with a pH range of 4.5 to 5.2. Soil pH levels above 6.2 are not suitable for optimal growth and production. They require well-drained clay soils due to their shallow root systems and benefit from a high organic matter content of 20–50%. Blueberries are sensitive to nitrate nitrogen and are often fertilized using ammonium sulfate. In cases where the soil pH is too high, it can be adjusted by applying sulfur to lower the pH to the desired range.
Climate for Blueberry farming
Blueberry is a fruit primarily suited to temperate zones and requires chilling for flowering, with the specific chilling hours varying by type. Northern highbush varieties need 800–1100 hours, rabbiteye types require 350–800 hours, southern highbush varieties need 200–700 hours, and lowbush blueberry demand over 1000 hours. These chilling requirements are essential for proper bud development and successful fruiting.
Northern highbush
Dormant flower buds and canes are destroyed at temperatures of -23°C or lower.
Southern Highbush
More frost prone because they have very short winter chilling requirement
Rabbiteye
Dormant bud and cane killed at or below -20°C
Lowbush
More cold hardy
Open flowers of all blueberry types are killed at -2°C, while relative humidity does not pose a problem for the plant.
Day Length
Day length plays a crucial role in plant growth and flowering, with long days of more than 12 hours of light promoting vegetative growth. Growth is most vigorous at 16 hours of light, which can completely suppress flowering, though this varies by variety. In contrast, maximum flower bud development occurs under shorter day lengths of around 8 hours of light.
Botany
Plant Characteristics
Highbush, Rabbiteye
Blueberry plants are erect, woody, perennial, and deciduous shrubs. Highbush varieties typically grow to 4 to 6 feet when cultivated, reaching up to 12 feet in the wild. Rabbiteye varieties, on the other hand, can grow 4 to 10 feet in cultivation and up to 20 feet in their natural habitat.
Lowbush
These plants are creeping and grow to a height of less than 2 feet, with a rhizomatous growth habit where the main portion of the plant is an underground stem located 1 to 3 inches below the surface. The rhizome produces upright shoots along its length, allowing the plant to spread and establish. The shoots grow vegetatively during the first year and bear fruit in the following year.
Leaves
The leaves are small, measuring 1 to 2 inches in length, and have an ovate or elliptic shape with an acute tip and an entire margin. Highbush and rabbiteye types have similar leaves, while lowbush varieties feature smaller leaves with mildly serrate margins.
Inflorescence
The inflorescence is a short raceme, measuring 1 to 2 inches in length, and is located on the upper portion of one-year-old shoots. Each inflorescence typically contains 7 to 10 flowers, although the number can range from 1 to 16.
Flower
The flowers are white or creamy, with some cultivars exhibiting a pinkish hue. They are urn-shaped, measuring 6 to 10 mm in length, and feature very short pedicels. The flowers have inferior ovaries, five calyx lobes, and five petals fused to form a tubular or bell-shaped corolla. They typically hang downward, adding to their distinctive appearance.
Pollination
Most northern highbush blueberry cultivars are self-fruitful, though some benefit from cross-pollination, which enhances fruit size and set. Southern highbush cultivars are only partially self-fruitful, requiring pollinizers in commercial plantations. Rabbiteye and lowbush cultivars are highly self-incompatible and depend entirely on pollinizers to produce fruit. All species require a high fruit set, typically 60–80%, to achieve a full crop, with no thinning practices involved. Bees are essential for pollination, even in self-fruitful varieties, as the inverted flower structure causes pollen to fall out without reaching the stigma. Bumblebees and wild bees are particularly effective natural pollinators.
Fruit
The fruit is classified as a false berry, as it is berry-like but develops from an inferior ovary, unlike true berries that originate from a superior ovary. Highbush and rabbiteye varieties produce fruit that ranges from blue to black, while lowbush varieties yield fruit that varies from black to bright blue.
Fruit Growth and Development
Flowering to maturity
- Northern and southern highbush – 45 to 75 days
- Rabbiteye – about 90 days
- Lowbush – 75 to 90 days
Weed Control
Weed control is crucial in blueberry production as the plants are poor competitors for moisture and nutrients due to their shallow root system, making clean cultivation challenging. Using a thick layer of organic mulch is an effective solution for managing weeds while also conserving moisture, maintaining proper soil acidity, and enriching the soil with organic matter. Recommended mulching materials include well-rotted sawdust, woodchips, pine straw, or other organic materials, applied in a 6-inch layer during the fall of the planting year.
A 50-50 mixture of sawdust and woodchips is ideal, as woodchips prevent wind erosion and sawdust enhances water movement. To compensate for decomposition, an additional 2-inch layer of mulch should be added annually. Highbush cultivars show a dramatic response to soil mulching, with yields increasing by 2 to 3 times compared to unmulched plants.
Fertilizer Management
Follow the link for “7 Best fertilizers for blueberry.”
Pruning
Pruning blueberries is essential to encourage the production of vigorous new growth, as the fruit develops on the previous season’s growth. Proper pruning improves sunlight penetration, enhances berry quality, and facilitates efficient mechanical harvesting by narrowing the plant’s base. This reduces the effort needed to detach fruit from old, stiff canes and minimizes damage during harvesting. Additionally, pruning helps control plant height, making hand-picking and mechanical harvesting easier and more efficient.
Propagation
Hard and softwood cutting are the most popular methods
Hardwood cutting
Hardwood cuttings are taken from pencil-sized, one-year-old shoots during January and February for propagation purposes.
Softwood
Softwood cuttings are collected at the end of the first growth flush, typically around June, for propagation.
Maturity
The primary maturity indicator for blueberries is the development of a blue color. The berries transition from green to pink and then gradually to blue as they ripen. Ripe berries can remain on the plant for several days or even weeks, continuing to accumulate sugar. Blueberries are climacteric fruits, meaning they undergo significant physiological changes during ripening.
Harvest Method
Blueberries do not ripen all at once and are typically harvested multiple times. For the fresh market, berries are hand-picked to ensure quality, while machine harvesting is primarily used for processing. Multiple machine harvests are required, usually conducted once a week over a span of three weeks, to collect ripe fruit.
Mechanical harvesters are two types:
- Over-the-row : Over-the-row – replaces 100 hand pickers
- Hand held vibrator and catch frame harvester
Sorting
Unripe berries must be sorted out.
Storage
Blueberries are highly perishable and can be stored for up to two weeks at 0°C with 90 to 95% relative humidity. However, they are sensitive to chilling, and fruit rot caused by pathogens such as Botrytis, Alternaria, Phomopsis, and Anthracnose poses a significant storage challenge.
Diseases
Mummy berry
Caused by Monilinia vaccinii-corymbosi
Most widespread disease
- Primary infection of expanding shoots and inflorescence called shoot blight: Spring frosts can kill leaves, shoots, and flowers, significantly increasing the risk of shoot blight. The fungus responsible produces spores in dead plant tissues, which are spread through insects, wind, or rain splashes, facilitating the disease’s spread.
- Secondary infection of the flowers and ovary of the flower: Fruits from infected ovaries develop fungal outgrowths inside, leading to mummified berries at harvest. The fungus overwinters in these mummified fruits, causing significant damage. This can result in up to 60% production loss and up to 50% loss of planting, severely impacting yields.
Control
- Sanitation is important to control
- Removal of old mulch or covering with new mulch
- Fungicide spray at bud break and at full bloom
Stem Blight and Canker
Caused by Phomopsis vacinii
Twigs and blossom blight and drying of fruit clusters
- Canker in Canes
- Cane collapse in mid-summer
Insects
Blueberry maggot (Rhagoletis mendax)
- Major fruit pest of blueberry
- Adults are a small fly
- Lay eggs inside the skin of developing fruit
- Larvae feed in the fruit
- Often undetected
- When picked berries appear mushy and leak juice easily.
Cranberry fruit worm
- Adults lay eggs on the calyx end of small green berries
- Larve enter into the fruit and eat fruit pulp
- May have pin-sized entry holes
- Infected fruit turn blue prematurely and shrivel
