We have a general guide to getting started with shrub and vine fruit here.
Site Selection and Preparation
- Choose at least two varieties for pollination. Plant at least one plant per person; two to four plants if you plan on fresh eating and freezing or preserving berries.
- Choose as sunny a site as possible. At least 6 hours of sun a day are necessary for fruit quality.
- Well drained soil free of weeds and rich in organic matter is ideal. For most soils, work in well-rotted sawdust or bark at planting so that the soil is 1/2 to 1/3 organic matter. Avoid mushroom compost as it is usually too high in pH.
- In very wet soils, consider building raised beds 3′-4′ wide and 8″-12″ high.
- Plant your blueberries where you can irrigate them during dry summer weather. Constant moisture is essential for success, especially for young plants.
- When planting, set the plant in the soil slightly high, mulch to the crown of the plants. The mulch should be 1″-2″ thick.
- Compact Highbush and Highbush varieties should be spaced 4′-6′ apart, with rows at least 8′ apart.
- Blueberries depend on both wind and insect pollination, so should be planted within 20′ for fruit set.
- Dwarf varieties can be spaced 1′-3′ apart.
- Consider using blueberries in the landscape. All the deciduous blueberries have good fall foliage colors and ornamental twigs.
Pruning and Cultural Care
- Remove all blossoms the first year. At planting, remove weak wood, and cut back strong stems by 1/3rd.
- Annually, in early spring, remove weak wood at the base, and older, twiggy wood by cutting to the ground. Brightly colored wood with long (3″ or more) laterals bear the most fruit. Cutting older wood out promotes this kind of growth.
- Fertilize by using acid fertilizers (Rhododendron Food) or cottonseed meal. Apply once in early spring and again in late spring. Water in!
- Blueberries are not drought tolerant! Regular summer water is necessary for good production.
- Keep the plants weeded and mulched. Rake, turn, and replace the mulch each spring at pruning time. This helps prevent mummy berry disease.
- Protect ripening fruit from birds. Mylar ‘scare tape’ can be effective when bird pressure is low. Nets can be draped over the plants, but check daily and remove birds who have gotten in. A frame over the berries for netting allows easier harvest than draping nets.
Pests and Diseases
Blueberries are well suited to our climate, but there are a couple of fairly common problems that can affect them.
The most common disease of blueberries in the home garden is mummy berry. This fungal disease infects the blooms, and as the berries set and ripen, they shrivel and become gray in color, dropping to the ground. The ‘mummies’ then release spores the following spring to infect the new blossoms. Severe infections can also cause the twigs to die back. If you see mummy berry affecting your plants:
- Shallowly cultivate under the plant in fall after leaf drop to bury the mummies
- Annually during dormancy apply a new sawdust or bark mulch layer to further bury the mummies.
- Remove and destroy any mummified berries you see during the growing season.
Spotted wing drosophila is an Asian fruit fly that appeared in Western WA in 2009. The fruit fly lays its eggs on ripening soft fruit, including blueberries. The larvae hatches, and eats inside the fruit until the fruit drops, then exits the fruit to pupate in the ground. If you are finding small white maggots in your berries at harvest, this is the most likely culprit.
- Harvest fruit frequently and use or freeze
- If you think you have SWD in your berries, you can confirm by setting out vinegar traps to monitor for the flies.
- If flies are present in large numbers, you can use spinosad or neem based sprays.
The most common problem with blueberries is not pests or diseases, but problems with establishing young plants. Blueberries are shallow rooted plants that need summer moisture. Weed or grass competition or inadequate irrigation are usually the problem. They are also subject to root damage from mice or voles. Setting up drip irrigation at planting is a good idea. Mulches at least 2″ deep are recommended, with annual additions. Blueberries are relatively heavy feeders, so need fertilizer on an annual basis.