Blueberries include several species of flowering, fruiting shrubs within the Vaccinium genus, all native to North America. Blueberry bushes have pointed, oblong leaves that are leathery to the touch, turning a brilliant red in the fall. The flowers appear in clusters of small, white, bell-shaped blooms in late spring, leading to deliciously edible berries that ripen from green to a deep purple-blue. Relatives within the Vaccinium genus include the bilberry, cranberry, huckleberry, and lingonberry.
Cultivated blueberries are continually being bred for higher yields, heat and cold tolerance, and better pest resistance. Still, some people prefer the blueberries that grow wild in forests and fields. Wild berries are smaller, and it will take you a while to pick enough for a pie, but many people find them the sweetest to eat.
Blueberries are best planted in early spring. Be patient: Three-year-old plants may produce a small harvest, but a meaningful harvest may take as long as six years.
|Botanical Name||Vaccinium spp.|
|Plant Type||Deciduous fruiting shrub|
|Size||1 to 6 ft. (depends on variety)|
|Sun Exposure||Full sun|
|Soil Type||Rich, well-draining; high in organic matter|
|Soil pH||Acidic (4.0 to 5.2)|
|Hardiness Zones||3 to 10 (varies by species)|
|Native Area||North America|
How to Plant Blueberries
When selecting blueberry bushes, the best choice is bare-root plants that are 2 to 3 years old. Older plants suffer more transplant shock and will still take a few years to begin producing large harvests. You can mix some peat moss into your planting hole to keep the soil loose, acidic, and well-draining.
Blueberries are self-fertile, but for best pollination, plant more than one cultivar. Blueberry plants should be spaced in a row about 4 to 5 feet apart; adjacent rows should be spaced 9 to 10 feet apart, which will provide plenty of room for harvesting. For bare-root plants, spread the roots out into a prepared hole, then cover them with soil amended with organic material. For container-grown bushes, plant them about 1 inch deeper than they were in the nursery pot.
Mulch after planting. Evergreen wood chips, like pine or cedar, sawdust, and pine needles will help keep the soil acidified.
Blueberry plants need full sun to grow and fruit well, and to avoid common diseases.
Blueberries like very acidic soil, with a soil pH in the rage of 4.0 to 5.2. They also like soil rich in organic matter. If your garden has heavy clay soil, blueberries will fare better in raised beds. Sandy soil is preferable to dense, clay soil.
To get the right soil pH for growing blueberries, it’s best to amend the soil the season before you intend to plant. Garden sulfur or aluminum sulfur can be mixed into the top 6 inches of soil to lower the pH as needed. If you have your soil tested at a garden center or your local extension office, they will be able to tell you how much sulfur you’ll need. It’s wise to retest your soil before actually planting, to make sure you’ve achieved the results you were after. Continue amending and tweaking the soil periodically, since soil tends to revert to its original pH.
Be sure the plants get a deep watering at least once per week. Blueberries are shallow-rooted and need at least a couple of inches of water each week, more during dry spells.
Temperature and Humidity
The temperature needs of blueberry bushes vary according to the species. The traditional highbush types prefer humid air and a cold winter climate, but the types bred for southern gardens do not tolerate freezing temps. Most types prefer a fairly sheltered location, protected from strong winds.
Don’t fertilize your blueberries in their first year. The roots are sensitive to salt until the plants are established. Ammonium sulfate is usually used as a fertilizer for blueberries, as opposed to the aluminum sulfur used to lower the pH. But you can use any fertilizer for acid-loving plants, including blueberry food and azalea food.
It’s not uncommon for blueberry leaves to begin to yellow or look chlorotic. Although this is usually a sign of iron deficiency, it is probably not caused by a lack of iron in the soil. More likely, this symptom is telling you that the soil pH is too high and the blueberry plants cannot access the iron that is already there. If you see yellowing progressing, have your soil pH tested, and make adjustments.
There are four main types of blueberries grown in home gardens. Plant breeders keep improving the vigor and disease resistance of fruit trees, so it’s hard to recommend varieties without updating them every season. The varieties mentioned here are old favorites. Check with your local Cooperative Extension office for the most current recommendations for your area.
For colder northern climates, these are the main varieties:
- Highbush (Vaccinium corymbosum) is a 6-foot shrub hardy from Zone 4 to Zone 7. This is the most common and most productive type of blueberry. Varieties good for cold winters include ‘Bluecrop’, ‘Blueray’, ‘Herbert’, ‘Jersey’, and ‘Meader’. Types known for big berries include ‘Berkeley’, ‘Bluecrop’, ‘Blueray’, ‘Coville’, ‘Darrow’, and ‘Herbert’. There is also a variety that produces pink blueberries, 'Pink Lemonade'.
- Lowbush (Vaccinium angustifolium) are bushes well suited for the coldest climates, as far north as zone 3. They have a much different growth habit, growing only 1 foot or so and spreading in a creeping fashion. Native to the northeast U.S. and southern Canada, the berries have a waxy covering that makes the fruit look grayish. These are sometimes considered a "wild" blueberry, and there aren't many named cultivars available.
- Half-high blueberries are recent breeding development, including varieties developed by crossing highbush and lowbush species. Most of these were developed in Minnesota and Michigan and grow 18 to 48 inches high. Popular cultivars include 'North Country', 'Northblue', and "Northland'. The berries are typically a little less sweet than highbush blueberries, but they work well in pies, jams and jams, and preserves.
For warmer southern climates, consider these more popular choices:
- Rabbiteye (Vaccinium virgatum), was previously categorized as Vaccinium ashei. It is grown mostly in the southeastern US. Growing as much as 15 feet tall, it requires two or more varieties in order to pollinate correctly. Recommended varieties include ‘Powderblue’, ‘Woodard’, and ‘Brightwell’. 'Delite' is another good late-bearing variety. Rabbiteye blueberries are good choices for gardens in zones 7 to 9.
- Southern highbush (hybrids of V. virgatum, V. corymbosum, or V. darrowii) is considered somewhat hard to grow, but several cultivars are popular for southern gardens, including ‘Emerald’, ‘Windsor’, and ‘Springhigh’. These are shorter, 3- to 6-foot-tall bushes with a 4- to 5-foot spread. They are grown in zones 7 to 10.
Most blueberry plants will start to produce a small harvest by their third year, but won’t begin to produce fully until about their sixth year. Mature blueberry bushes produce about eight quarts of berries per bush. It’s possible to extend your blueberry harvest by planting early, mid- and late-season varieties, instead of all one variety.
The only reliable way to know if blueberries are ready to pick is to taste one or two. Blueberries are their sweetest if allowed to stay on the plant at least a week after turning blue.
As with all berries and fruits, blueberries will continue producing their best if they are maintenance-pruned. In the first two years, remove any flowers that appear. Your plants will get bigger and more vigorous because of this. Berries are produced on branches in their second year of growth, so it’s important to be constantly renewing the blueberry bush.
You can leave the flowers on for the third year. You won’t get many berries, but no pruning is necessary until the fourth year.
Beginning in the fourth year, prune your blueberry bushes in early spring, while they are still dormant. Prune out any dead or injured branches, any crossing branches, and any weak, spindly branches. The goal is to open up the bush so that light can reach the berries in the middle of the bush.
Maintenance pruning in subsequent years aims at thinning out the older branches to encourage new growth. Cut back the oldest, thickest branches to near ground level and prune back branches that have gotten too long or that are growing too thin. Older branches will look gray; newer branches will have more of a reddish tinge.
Berries form on the fruiting spurs of side branches. The flower buds will be larger, plumper, and rounder than the pointed leaf buds.
Like many woody shrubs, blueberries can be propagated by taking softwood cuttings and rooting them. In early spring, choose a healthy shoot and cut off the last 5 inches of growth from the tip of the stem. Remove all but the top two or three leaves, and plant the cutting immediately in a moist growing medium. Grow it in a sheltered location until the cutting develops a good network of roots.
It is also possible to propagate blueberries by planting seeds found inside the berries, or by transplanting suckers that appear at the base of the bush.
Common Pests and Diseases
By far the biggest problem growing blueberries is keeping away birds. Netting can be successful if you have only a few bushes, but if you have a large blueberry garden, consider using a bird deterrent that sends out a bird-in-distress call, which will repel birds.
Insects to be on the lookout for include: blueberry tip borer, cherry fruit worm, cranberry fruit worm, and plum curculio. If these are common pests in your area, check with your local extension for the prescribed deterrents and treatments.
There are some fungal diseases that can affect blueberries, including powdery mildew and leaf spot diseases. Your best defense is to plant genetically resistant varieties. It also helps to give your plants plenty of space for good air circulation, plant in full sun, clean up any fallen debris, and replace the mulch annually, so the spores cannot over-winter in the area. If you should experience problems, you may need to use a fungicide labeled for use on edible plants.
Some other common blueberry diseases to keep an eye out for include:
- Anthracnose: This fungal disease spreads rapidly in damp weather. Symptoms are bright pink clusters of spores on the developing berries.
- Botrytis: Another fungus that thrives in damp conditions, botrytis will cause the fruit to shrivel and rot.
- Canker: Fusicoccom (Godronia): This disease begins in the lower parts of the canes. You’ll notice small reddish spots that will enlarge into a bullseye. If left untreated, they will eventually circle and girdle the cane, causing it to die-back.
- Mummy berry: This is one of the more serious diseases to affect blueberries. Mummy berry is caused by a fungus. The first signs of infestation are the blackening of the flower clusters, which eventually die. Because it is a fungus, the spores can linger and infect the remaining blossoms. The resulting fruit turns tan and hard, looking like mummified berries.
- Twig blights (Phomopsis): Twig blight can start off looking very similar to canker. As twig blight progresses, it can also affect the crown, smaller branches, and twigs as well as causing leaf spotting.
How to Grow Blueberries in Pots
Blueberries are popular in home gardens because they can grow in a small space, even in containers. In fact, they are one of the easiest berries to grow in containers. Some good varieties for containers include:
- 'Dwarf Northblue', a mid-season bush that grows 20 to 24 inches
- 'Dwarf Tophat', an 18- to 20-inch late-bearing bush that requires no pollinator
- Bushel and Berry series, including the cultivars 'Jelly Bean' and 'Pink Icing'