Grow heart-healthy blueberries

Blueberries are one of the easiest berries to grow and a great plant for beginner and organic growers.

Freshly picked blueberries are one of summer’s great treats, so plant now for a delicious serve. These heart-healthy berries are chock full of antioxidants, as well as anti-inflammatory, antimicrobial and anti-carcinogenic properties.

Growing conditions

Blueberries like a free-draining, acid soil with lots of organic matter mixed in. Dig compost and a little peat into your soil or potting mix before planting. Rabbiteye blueberries are not as fussy as Highbush varieties and do not need such an acid soil (see note on blueberry types below). They will tolerate a pH of 5.5, whereas other blueberries grow best below 5.5, between 4.5 and 5.5.

Plants will grow more vigorously and fruit better if planted in full sun, so choose a warm, sunny spot in the garden or patio. They will also fruit better if another blueberry variety is planted nearby for pollination. Check the label to see which blueberries make suitable ‘partners’. The best ones are those that flower at the same time (some are early bloomers, some are mid-season bloomers, others are late bloomers).

Dig a hole three times the width of the pot and the same depth as the root ball. If planting more than one bush for cross-pollination purposes, plant no more than 3m apart. Blueberries also make excellent low hedges. For hedges, position about 75-90cm apart.

Plants have a shallow root system, which means they don’t have the ability to dig deep below the surface in search of water. Make sure you supply plenty of water during the growing season, particularly when flowers and fruit are forming. The first year is critical for the establishing of young bushes, so don’t skimp on water. If you have several bushes it may be worth investing in an irrigation system. Keep the immediate area around your bushes free of weeds and grass to cut down on competition for water and nutrients.

Feeding

In the first three years, blueberries require only a light feed. You can apply a slow-release fertiliser in spring, but a continuous top-up of organic mulch will be beneficial. Compost is ideal, or an acidic mulch such as pine needles or peat. Avoid mushroom compost and wood ash, both of which have a high pH level.

Pruning

Blueberries don’t require a great deal of pruning other than the removal of diseased wood or weak growth. Fruit is borne on second year wood, so if pruned regularly you won’t get any fruit. After four or five years, the oldest branches may need cutting back to encourage fresh, vigorous growth. Any leggy growth can be cut out to encourage plants to bush up.

Propagation

If you’d like to increase your blueberry collection you can take softwood cuttings in early spring. Cut stems about 15cm long and strip the bottom leaves, leaving two or three at the top. Place the cuttings in a pot filled with sand and peat moss and leave in a warm, bright spot out of direct sunlight. Keep the pot moist and roots should form in about eight weeks. Grow on until plants are big enough to plant in the garden, or pot up into a larger container.

When to pick

Blueberries are ready to pick when they’ve turned a nice deep blue. The fruit should easily pull away from the plant when ripe. You can leave the fruit on the bush after they’ve turned blue to develop a more intense flavour, though if left too long they’ll drop off.

You might want to throw over bird netting too, otherwise you could lose your fruit to the neighbourhood wildlife.

Types of blueberries

There are three types of blueberries cultivated worldwide – Lowbush, Highbush and Rabbiteye, though in New Zealand we grow only the latter two. Highbush blueberries are the most common, although Rabbiteyes are becoming increasing popular. Within the Highbush group there are Northern Highbush and Southern Highbush blueberries. Northern Highbush varieties require a high winter chilling, at least 700 hours per year, while Southern Highbush varieties require only about 400 hours, making them ideal for the warmer north. Northern Highbush varieties include ‘Duke’, ‘Elliot’, ‘Jersey’ and ‘Nui’, among others, while Southern Highbush varieties include ‘Blueberry Muffin’, ‘O’Neal’, ‘Southern Blue’ and ‘Summer Blue’.

Highbush blueberries are deciduous and self-fertile, although another variety planted close by will produce a larger, better crop.

Rabbiteyes are evergreen and at least two varieties are needed for cross-pollination. They are suitable for all parts of the country, although they don’t like very cold conditions. Varieties include ‘Blue Dawn’, ‘Blue Magic’, ‘Centurian’ and ‘Powder Blue’, among others.

Rabiteye varieties crop much later in the season, from February to early April, whereas Highbush varieties will produce fruit from mid-November to mid-February. If you plant several different varieties from each group you can spread the fruiting season considerably.

Rabbiteyes are also more tolerant to drought (although regular watering is best) and less susceptible to the root rot phytophthora, although care is still needed with planting to avoid disease.