Blueberries are long-lived perennials that do well in our climate. Here are a few tips to ensure that your blueberries provide a bountiful harvest for many years to come.
Plant blueberries in the fall or early spring. Although you can plant just one blueberry and get a decent crop, blueberries produce more and bigger berries when pollinated by a different variety. If you plant several varieties that ripen at different times, you also will extend the harvest season. But be sure to select varieties suited to our climate. (See sidebar on B6)
Plant blueberries in an area with full sun and well-drained, acidic soil (pH of 4.5-5.5). Blueberries are acid-loving plants. (They don’t really love acid so much as need certain nutrients that become more available in acidic soils.)
Because acidifying the soil takes time, check the pH six to 12 months before planting. If the soil is too alkaline, amend the planting site with elemental sulfur. The amount applied will depend on the starting pH and the texture of the soil.
In planting your blueberry, prepare a hole that is three times as wide as the root system. Add one gallon of soaking wet peat moss to the hole, mixing it with the native soil.
If you are planting bare-root plants, spread the roots out carefully. Position the plant with the uppermost roots one inch below ground level. If you are planting a blueberry grown in a container, set the plant at the same depth as at the nursery. Clip encircling roots and cut vertical slits in the root ball if the roots are dense and tightly packed into the pot.
Space plants 4-6 feet apart to allow room for growth and rows 9-10 feet apart.
Mulch with sawdust, wood chips or straw to maintain soil moisture and discourage weeds. Because blueberries have roots near the soil surface, hand weed. Make sure your blueberries get 1-2 inches of water each week.
Remove flowers and do not let plants fruit for the first two seasons. Plants from which flowers have been removed will reach mature size and productivity sooner.
Fertilize your blueberries starting the second year and continue every year thereafter. Fertilize them with ammonium sulfate in late April, late May and again in late June. Amounts of fertilizer depend on plant age. (For details, see “Growing Small Fruits in the Home Garden” at cru.cahe.wsu.edu/CEPublications/EM103E/EM103E.pdf.)
Fish emulsion is an acceptable organic regimen for blueberries, but is best applied in small amounts throughout the growing season. Oregon State University recommends diluting 1 tablespoon of fish emulsion in 1 cup of water and applying to each plant once in late April, twice in May, twice in June and once in early July.
Observe plants to guide fertilizing practices. If shoot growth is poor, give plants the maximum recommended amount of fertilizer.
Blueberries put on new canes each year. Individual canes fruit when they are one year old and produce
well for three or four years. After about five years, berry production on that cane falls dramatically.
Beginning the third year after planting a bush, prune your blueberries during the dormant season (January through March).
1) Remove broken or diseased branches and those low to the ground.
2) Remove canes six years of age or older which can be recognized by their thick diameter, twiggy tips and presence of lichens.
3) Remove all but two or three of the new canes formed the previous summer. Keep those that are strong and well placed around the bush.
When removing a cane, cut it all the way back to the crown of the plant or to slightly above a vigorous side branch.
Removal of older canes encourages growth of new canes. Therefore, a regular pruning regimen is necessary for good blueberry production.
Jeanette Stehr-Green is a WSU-certified, Clallam County Master Gardener.