Growing Blueberries In Containers
Blueberries are ideally suited for growing in containers because they have a shallow root system that easily adapts to the tight confines of a container. Another reason to grow them this way is that blueberries require specialized soil with a low, acid pH (ideal range: 4.5 to 4.8).
With in-ground plantings, maintaining this low pH may require a concerted, ongoing effort. In a container or raised bed, you can create the ideal soil pH at planting time and have it last for six to 10 years before you have to tackle major soil amending. (At that point, bushes also benefit from root pruning, so it's a win-win situation.)
When you first purchase a blueberry bush, tuck it in a 12-inch pot for the first two to three years. Then transplant it into a 20-24-inch-diameter container – about the size of a whiskey barrel planter.
Get The Soil Right
Fill containers with this soil mix, which fostered the best yields in trials at Colorado State University:
- 40% untreated, raw peat moss
- 40% coir (shredded coconut husk, available at most garden centers)
- 20% perlite
- A handful of soil sulfur per plant
While blueberries are technically self-pollinating, you'll get better, more consistent yields when you plant more than one type for cross-pollination. Choose types with overlapping flowering times. Check with your local Cooperative Extension System office for the best locally-adapted varieties.
Other Keys To Success
- Site. Blueberries need full sun.
- Hardiness. Because containers expose roots to winter air temperature, choose plants hardy to two zones colder than your zone. For example, if you grow in USDA zone 5, choose blueberries hardy to USDA zone 3.
- Mulch. Apply an acidifying mulch, such as oak leaf compost, pine needles or pine bark, to maintain soil moisture and reduce heating.
- Water. Keep soil consistently moist. Monitor water pH; an alkaline water source shifts soil pH.
- Soil pH. Check soil pH frequently using a pH soil-probe. If pH moves above 5.0, add cottonseed meal or iron sulfate.
- Fertilizing. Use fertilizers formulated for acid plants, such as Azalea, Camellia or Rhododendron. Never use fertilizers containing nitrates. Fertilize 4-6 weeks after planting.
- Flowering. During the first season, remove all flowers to establish strong roots.
- Pruning. Established plants require annual pruning in early spring. Check with your local Cooperative Extension System office to learn pruning techniques.
- Picking. Protect ripening berries with bird netting. Allow berries to turn blue, then wait up to a week before picking to allow berries to sweeten. Berries don't ripen or sweeten after picking.
Blueberries For Pots
Try these varieties for growing in containers. You'll purchase 2-3-year-old plants. Shrubs start bearing strongly in the fourth year. At maturity (8-10 years old), expect yields from 2-12 pounds of fruit per bush.
- Top Hat1 (true dwarf Northern Highbush)
- Chippewa (half-high)
- Northcountry (half-high)
- Northblue (half-high)
- Misty (Southern highbush)
- O'Neal (Southern highbush)
- Sharpblue (Southern highbush)
- Sunshine Blue1 (semidwarf Southern highbush)
1-Small size ideally suited for growth in containers.