Blueberries: plant, care & harvest tips
Blueberries are the best berry for home growers. These thornless plants are easy to grow, their fruit is delicious and nutritious, and a spring planting could reap a small crop of fruit as soon as this summer.
Blueberries hail from North America and Canada, and are divided into types based on the climate conditions they need.
The Northern Highbush types, such as 'Nui' and 'Dixi', need cold winters so are best in temperate regions. These deciduous varieties flower late in spring so usually avoid the frosty season in Southern spots.
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The Southern Highbush varieties, with their early spring flowering, are good in warmer regions where winters are unlikely to be frosty. The early flowering time means the fruit is ripe in early summer. These varieties will hold their leaves well through the winter -- 'Misty' is almost evergreen -- so are great for ornamental plantings.
Rabbiteye types (Vaccinium ashei) are halfway between the two, flowering in mid spring and suitable for both cooler and warmer regions. Plant 'Blue Dawn' for berries in January and February, 'Blue Magic' for berries from February into March, and 'Centurion' to harvest into April.
While blueberries are considered self-fertile, all are best planted with a different variety to ensure maximum pollination and heavier yield. Both plants should be of the same type, for example two Rabbiteye varieties. While the two varieties will flower simultaneously, they often fruit at different times, spreading the harvest.
In the wild, blueberry plants thrive in peaty forests where the soil has a low pH. Blueberries likes soil with a pH of between 4-4.5, so it's best to make a dedicated blueberry bed. It doesn't need to be very deep, as these plants have a shallow and fibrous root system. A specific area also makes it easier to cover bushes with netting in summer, to protect the fruit from birds.
PREPARING YOUR BLUEBERRY BED
* Blueberry likes acidic soil conditions. Prepare the bed with a 50:50 mix of peat and soil (or half and half peat and container mix for pots).
* Mulch around the base of the plants with well-rotted sawdust from untreated timber.
* Plant blueberry bushes half a metre apart to grow as an edible hedge, or two metres apart to treat as individual bushes.
CARING FOR YOUR BLUEBERRIES:
* Repeat the mulch each year at the start of summer.
* Keep the area around the base of the bushes weed free, as the shallow roots will have trouble competing with the vigorous roots of invading weeds.
* Take care when using nitrogen fertilisers -- the roots of blueberries are very sensitive to nitrates. Avoid these fertilisers completely when growing blueberries in pots. Use ammonium sources of nitrogen, such as ammonium sulphate, instead. Avoid using animal manure and lime too. (Here's everything you need to know about fertilising your plants.)
* Prune blueberry plants regularly. Just remove any dead of damaged shoots and very low growth that will hang to the ground when laden with berries. Prune in very early autumn during a dry spell of weather. Avoid winter pruning due to the increased risk of fungal infections in wet conditions. Bushes will naturally grow to around 1.2m to 1.5m tall and can be pruned to shorter than this if desired. You might be tempted to prune back vigorous growth that looks like water shoots to maintain a tidier bush, but these are usually very productive with fruit.
Most varieties are ready to harvest when the fruit turns deep blue, though some varieties need another week or so of ripening after this to fully take on flavour.
Bushes will usually produce a small crop in the first year, which technically should be removed to allow the plant to establish -- although wasting this delicious fruit is difficult even for the most law-abiding gardener! -- with increasing crops each year. Established plants from around five years old should produce 5-10kg of valuable, tasty blueberries each year.
- NZ Gardener