CORVALLIS, Ore. – If you love blueberries and are considering growing your own, it's a good idea to begin preparing your site and soil well in advance. Your current investment in time and continuing care will allow these delicious, deep-blue berries to produce for as long as 50 years.
Blueberries, favored for their sweet juicy taste, also are known for their high level of antioxidant activity, thought to help protect the body against free radicals and chronic diseases associated with aging.
Highbush blueberries, the most common in Oregon, are perennial, long-lived (40 to 50 years), deciduous shrubs with a mature height of five to seven feet, according to Bernadine Strik, Extension berry crops professor at Oregon State University. Attractive as ornamentals, they progress from a profusion of white or pink blossoms in spring to colorful foliage (fall) and wood (winter).
"You can grow plants in beds, rows, hedges or individually," Strik said. "Dwarf and semi-dwarf cultivars (varieties) can be grown in containers."
Fruiting season in Oregon is from late June until September, depending on cultivar.
It's best to plant more than one cultivar of blueberry, Strik advised. "Although most northern highbush cultivars are self-fertile, cross-pollination produces larger berries," she said. "And, if you plant two or more cultivars that ripen at different times, you'll lengthen the harvest season."
Northern highbush cultivars grown in home gardens in Oregon include (in order of ripening): Duke, Earliblue, Spartan, Patriot, Bluecrop, Jersey, Blueray, Legacy, Chandler and Elliott. See OSU Extension publication PNW 656, “Blueberry Cultivars for the Pacific Northwest,” for descriptions of these and other blueberry cultivars.
Blueberries need lots of sunshine and specific soil requirements. When choosing a site, Strik advises avoiding areas surrounded by trees, which can provide too much shade, compete for water and nutrients, encourage birds and deter air movement around the new plants. The berries grow best in well-drained, light, sandy loam that is high in organic matter and with a pH between 4.5 and 5.5.
Test the soil pH a year before planting. If you need to make the soil more acidic, it can take more than six months. According to Strik, poor plant growth from soil pH that is too high is the most common problem when growing blueberries in a home garden. (For more information about soil testing, see “Laboratories Serving Oregon: Soil, Water, Plant Tissue, and Feed Analysis,” EM 8677, and “A Guide to Collecting Soil Samples for Farms and Gardens,” EC 628, )
"If the pH is between 5.7 and 6.5," Strik said, "acidify the soil by adding finely ground elemental sulfur before planting."
The amount needed depends on how much the pH needs to be lowered and the soil type. More detailed instructions on changing pH, weed control, mulching, fertilizing, pruning, watering and care of established blueberry plants are available online in the OSU Extension publication “Growing Blueberries In Your Home Garden,” EC 1304.
If you decide to grow several plants, it's better to group them in a bed or row rather than scattering them around the garden, Strik explained. You'll get better results preparing an entire bed, rather than digging holes and preparing soil for individual plants.
Although blueberries require a uniform supply of water, they will not tolerate poor drainage. Ideal soils are well-drained with a water table 14 to 22 inches below the surface.
"Raised beds, however, can provide adequate drainage and aeration if they are from 12 to 18 inches high and three feet wide," Strik said. They can be constructed with wood walls, or you can make hills with just soil and sawdust.
"Before planting, incorporate organic matter such as Douglas-fir sawdust or bark to improve soil aeration and drainage," Strik said. "Yard debris compost can be used, but it often has a high pH (over 7.0, compared to 4.0 to 4.5 of Douglas-fir sawdust) and can be high in salts and thus not desirable for blueberries."
Spread sawdust to a width of about three feet and depth of three and a half inches. To aid in decomposition add two pounds of nitrogen per 100 feet of row length (10 pounds ammonium sulfate, 21-0-0). Incorporate the sawdust and fertilizer with a rototiller.
Plant healthy two-year-old plants from a reputable nursery in October or from March through April. "Prune off flower buds at planting and do not allow plants to produce fruit the first season," Strik said. "Be patient! Flower and fruit production hinders growth, and it's important that plants grow well the first year."
Here's a short checklist for taking care of mature plants:
- Add mulch gradually over the years to maintain a depth of six inches;
- Apply fertilizer in the spring, starting around bloom time;
- Water to maintain a uniform and adequate moisture supply;
- Pick fruit at optimum maturity;
- Prune in January or February.