Growing Highbush Blueberry

Highbush Blueberry is native to North America. The bush grows up to 2 m in height and blooms in the second half of May; the ripening season lasts from the beginning of July to the end of September depending on the variety. Prospective growers should bear in mind that Highbush Blueberry belongs to the heather family and has very particular requirements. If ignored, they will result in the failure of the plantation.

Site selection

When growing blueberries on commercial scale, it is important to choose soils that are light (sandy), acidic (pH KCL 3.5-4.5), rich in humus (ca. 10%), moist (ground water level from 60 to 100 cm) and well-aerated (lower layers of the soil should be permeable). In practice, such soils are usually found near or among pine forests. The blueberry has very low nutritional requirements. The optimum soil richness for this plant is:

phosphorus        1,5-2 mg P/100 g of soil
potassium           3-5 mg K/100 g of soil
magnesium         2,5-4 mg Mg/100 g of soil

If the values you find do not match those figures, the soil needs to be replenished during the preparation. The pH factor can be increased by liming or decreased by sulphuring the soil. A small reduction in soil acidity can also be achieved by adding acidifying, slowly decomposing organic substances, such as peat moss, composted bark or pinewood sawdust. When planting berries in a home garden, the optimum conditions can be obtained quite easily by mixing about 50 l of acid peat, leave soils, bark or composted sawdust into the planting hole. In the case of particularly unsuitable soils (very heavy, with high pH), the planting holes of 80-100 cm diameter and 30 cm depth should be lined with foil and filled with peat bog, bark and forest soil.

Plants and varieties

The plant material introduced on a plantation should be 2-3 years old, vegetatively propagated, supplied in a container or with a root ball. The choice of varieties for a particular plantation depends on a number of factors and should be consulted with an expert. A sensible approach on a small plot is to plant multiple varieties, from early to late season, prolonging the harvesting season from early July to late September and ensuring better pollination.

Highbush varieties

Spacing

On commercial plantations, rows should be at least 3 metres apart to allow for mechanical cultivation and easy harvesting. The space between plants in a row should be 0.9-1.2 m. The spacing in a home garden can be 1x2.5 m.

Irrigation

Water is one of the critical factors in blueberry growing. Due to their short and dense root system, blueberries are vulnerable to a lack of water. During dry season, plants should be watered at least once a week with about 10-20 l of water. With the recurrent periods of prolonged drought in late spring and early summer in recent years, setting up a commercial plantation without an irrigation system is very risky.

Cultivation

There are many possible ways of growing blueberries. On our farm, the best results are obtained using turf between rows and sawdust mulch in the rows of plants. Other planters use herbicide fallow or black fallow.

Weed management

The soil for planting must be free from persistent weeds! Depending on the type of weeds, use appropriate herbicide or mechanical soil working. The self-sowing weeds that appear once the blueberries have been planted should be promptly eradicated, as blueberries compete poorly for water and nutrients. Massive invasions of weeds can be prevented by mulching the rows of plants.

Mulching

Mulch limits the intrusion of weeds, reduces the amount of water lost, regulates soil temperature, and provides plants with organic substances. Mulch decomposes and needs to be replenished every 2-3 years. Both organic and synthetic mulches (like foil or fabric) work well. In our experience, the most effective mulch is made from coniferous wood sawdust.

Mineral fertilisation

Once the soil is replenished to its optimum richness prior to planting, the content of nutrients should be constantly monitored through analyses. Bear in mind that blueberries are very sensitive to a lack of nitrogen. When using mulch, the amount of nitrogen should be increased twofold. On the other hand, blueberry bushes are easily over-fertilised; therefore we recommend nitrogen fertilisation (ammonium nitrate, ammonium sulphate) in small amounts, with constant monitoring of the plants' requirements. It is best to learn about the symptoms of shortage or overabundance of nutrients in soil before starting a new plantation. In a home garden, young plants should be fertilised in autumn, once the vegetation period is over, with 30 g of mixed fertilisers per bush. In spring, preferably from early May to early July, reinforce the plants with nitrogen in three doses of 10 g of ammonium sulphate or two doses of 10 g of ammonium nitrate. You can use slow-release fertilisers (Plantacote, Osmocote), following instructions on the packaging for small doses, recommended e.g. for coniferous plants. Each year the dose of fertilisers should be increased by 1/3, so that in the 6th year from planting the bushes receive 150 g of slow-release fertiliser and 100-150 g of nitrogen fertiliser. You can also use specialist fertilisers for Highbush Blueberry and fertilise the plants according to the manufacturer's instructions.

Pruning

For the first 4 years since the blueberries are planted, we recommend sanitation pruning, i.e. removing shoots that are diseased, weak or suffered mechanical or frost damage. Prune old stems and those that block the light from 5th year onward by shortening or removing the oldest and densest shoots that have no one-year shoots. The most suitable time for pruning is towards the end of winter and in early spring.

Wind protection

Blueberries perform best in sunny and quiet locations protected from strong winds. On wider, more open spaces, you should consider planting protective belts, preferably consisting of coniferous trees.

Protection

Highbush Blueberries do not require extensive protection from pest and diseases, which is yet another plus from the point of view of the growers and consumers. When growing blueberries in a home garden, there is no need to use protective chemicals. Any pests should be destroyed manually. Diseased parts of the plants should be pruned.

Fruit and harvest

Yield from one fully mature bush (6-7 years from planting) depends on the variety and varies between 3 and 6 kg. A well-managed farm should bring a crop of about 10 tons per hectare. Berries are picked manually a couple of days after turning blue, when they have the desired flavour and aroma.