Blueberries include several species of flowering, fruiting shrubs within the Vaccinium genus, all native to North America. Relatives within the Vaccinium genus include the bilberry, cranberry, huckleberry, and lingonberry. Blueberry bushes have pointed, oblong leaves that are leathery to the touch and turn a brilliant red color in the fall. The flowers appear in clusters of small, white, bell-shaped blooms in the late spring, leading to deliciously edible berries that ripen from green to a deep purple-blue.
Selecting a Planting Site
Pick a spot that receives full sun but is sheltered from strong winds. Avoid a planting site that is close to tall trees or shrubs that might block the sunlight or compete for soil moisture and nutrients. Make sure the planting site has good soil drainage. You can mix some peat moss into your planting hole to keep the soil loose, acidic, and well-drained. Blueberries also can be grown in containers if they receive sufficient sunlight and moisture.
Spacing, Depth, and Support
Blueberry bushes should be spaced in a row about four to five feet apart; adjacent rows should be spaced nine to ten feet apart to provide plenty of room for harvesting. For bare-root plants, spread the roots out into a prepared hole, then cover them with soil and ensure the root ball is no more than 1/2 inch below the soil surface. For container-grown blueberries, plant them the same depth that they were in the nursery pot. Blueberry bushes are sturdy plants and generally don’t need any support structure.
Blueberry Plant Care
Light
Blueberry plants need full sun to grow and fruit well. This means at least six to eight hours of direct sunlight on most days.
Soil
Blueberries must be grown in very acidic soil with a soil pH in the range of 4.0 to 5.2. They also grow best in soil that’s rich in organic matter. If your garden has heavy clay soil, blueberries will fare better in raised beds where you can control the soil composition and pH. Sandy soil is preferable to dense clay. Add a layer of mulch after planting: Evergreen wood chips, sawdust, and pine needles will help to keep the soil acidic. 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 six inches of soil to lower the pH as needed. Your local garden center or extension office can test your soil 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 best results. Continue amending the soil periodically, because soil tends to revert to its original pH. It’s also common for blueberry leaves to begin to yellow. 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 indicates that the soil pH is too high and the blueberry plants cannot access the iron that is available in the soil. If you see yellowing leaves worsening, have the soil pH tested and make adjustments as necessary.
Water
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). You can also utilize an automatic irrigation system to ensure consistent water for your plants.
Temperature and Humidity
The temperature requirements of blueberry bushes vary according to the species. The traditional highbush types prefer humid air and a cold winter climate, but variants bred for Southern gardens do not tolerate freezing temperatures. Most types prefer protection from drying winds.
Fertilizer
Don’t fertilize your blueberries in their first year. The roots are sensitive to salt until the plants are established. Once your blueberries have been planted for one year, you can begin feeding them based on two main indicators: when the flower buds first open, then again when berries start to form. Remove weeds regularly to ensure soil nutrients are not being consumed by weeds rather than your blueberry bushes. Ammonium sulfate is usually used as a fertilizer for blueberries, as opposed to the aluminum sulfur used to lower the pH. You can use any fertilizer for acid-loving plants, including blueberry food and azalea food. Gardeners can either do foliar applications (applying directly to the leaves) or by fertilizing the soil, and many choose to use organic fertilizers like fish emulsion, compost, or manure tea.
Pollination
Blueberries can self-pollinate. However, for best results, plant two or more bushes—two is good, but three is better. The diversity will result in a higher fruit yield and larger fruits. Make sure the varieties you choose bloom simultaneously to ensure cross-pollination between the plants takes place.
Types of Blueberries
There are four main types of blueberry plants: highbush, lowbush, half-high, and rabbiteye. They are primarily classified by their size, and plant breeders continue to cultivate new varieties to improve their vigor. The main types include:
Highbush (Vaccinium corymbosum) is a roughly six-foot shrub hardy in zones 4 through 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 berries called ‘Pink Lemonade.’ 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, three- to six-foot-tall bushes with a four- to five-foot spread. They are grown in zones 7 through 10. Lowbush (Vaccinium angustifolium) are bushes well suited for the coldest climates, as far north as zone three. They have a much different growth habit from other types, growing about one foot tall 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 gray in color. These are sometimes considered wild blueberries, and there aren’t many named cultivars available. Half-high blueberries are a newer breeding development, including varieties developed by crossing highbush and lowbush species. Most of these 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 preserves. Rabbiteye (Vaccinium virgatum) was previously categorized as Vaccinium ashei. It is grown mostly in the southeastern U.S. Growing as high as 15 feet, it requires two or more varieties to pollinate correctly. Recommended varieties include ‘Powderblue’, ‘Woodard’, and ‘Brightwell’, ‘Delite’ is another good late-bearing variety. Rabbiteye blueberries are great choices for gardens in zones 7 through 9.
Blueberries vs. Huckleberries
Blueberries and huckleberries come from the same genus. The fruits look similar at first glance: they’re both small and round with a blueish color. However, huckleberries tend to be more tart than blueberries, and their seeds are noticeably hard when you bite into them (unlike blueberry seeds).
Harvesting Blueberries
Blueberries will typically be ready to harvest between June and August. Most blueberry plants start to produce fruit by their third year, but they won’t produce fully until about their sixth year. Mature blueberry bushes yield around eight quarts of berries per bush. It’s possible to extend your blueberry harvest by planting two or more bushes, such as early-, mid-, and late-season varieties. The only reliable way to know whether blueberries are ready to pick is to taste them. Ripe blueberries will readily come off the stem. Blueberries are their sweetest if allowed to stay on the plant for at least a week after turning blue. Hold a container under berry clusters, then gently pick them off with your other hand to drop the fruits into the container. Put them in the refrigerator, unwashed as soon as possible. They typically can keep up to a week when refrigerated (wash them before use). The berries can be eaten fresh or used in baked goods, and they also can be frozen and kept in the freezer for around 6 to 12 months.
Growing Blueberries in Pots
Blueberries are one of the easiest berries to grow in containers. They are popular in home gardens because they can grow in small spaces, including containers. Containers are especially ideal if you don’t have adequate soil conditions for blueberries. Use a container at least 18 inches deep with ample drainage holes. An unglazed clay pot is ideal because it will allow excess soil moisture to escape through its walls. Use one container per plant and choose a blueberry variety that remains fairly small. Select a potting mix made especially for acid-loving plants, then plant your blueberries at the same depth they were in the nursery pots. Keep the soil lightly moist but never soggy, and make sure the container gets plenty of sunlight. Use a fertilizer made for acid-loving plants in the spring.
Pruning
Blueberries will continue producing at their best with some maintenance pruning. In the first two years, remove any flowers that appear to help your plants grow bigger and more vigorous. You can leave the flowers on for the third year. They won’t produce many berries, but no pruning is necessary until the fourth year. Beginning in the fourth year, prune your blueberry bushes in late winter or early spring while they are still dormant. A good rule of thumb is to prune about 1/3 of the plant to encourage new growth. Using clean, sharp garden shears or a small wood saw, remove any dead, broken, crossed, or weak branches where they meet the main stem. The goal is to open up the bush so light can reach the middle, so it’s also important to trim any branches that cross each other. Maintenance pruning in subsequent years should aim at thinning out the older branches. Cut back the oldest, thickest branches to near ground level, then prune back branches that have grown too long or too thin. Older branches will look gray in color; newer branches will have more of a reddish tinge.
Propagating Blueberries
Like many woody shrubs, blueberries can be propagated by rooting cuttings taken from softwood or hardwood. Not only is this a cost-effective way to get a new plant, but it also helps to thin out mature plants. The best time to take softwood cuttings is in the early spring, while hardwood cuttings are best taken in late winter before new growth begins. Here’s how:
How to Grow Blueberries From Seed
Before blueberry seeds can be planted, they must first be put in the freezer for 90 days to mimic the winter cooling period. You can grow blueberries from fruit by freezing the blueberries, then mashing them or putting them in a blender or food grinder. Once macerated, the seeds sink to the bottom. Collect the seeds by separating them from the juice and pulp. Fall is the best time to plant seeds in warm climates, while spring is best in cool climates. Fill a flat tray with moistened sphagnum moss, sprinkle the seeds on top, then lightly cover them with more moss. Cover the tray with newspaper and place it in a room that stays between 60 and 70 degrees Fahrenheit. Keep the moss consistently moist. Seedlings should emerge in about a month, at which point you can remove the newspaper and keep the tray in bright, indirect light. Once the seedlings are two to three inches tall, they can be planted in an equal mix of peat moss, sand, and soil. Continue to keep them moist. They should be large enough to plant in the garden during the spring of their second year after the threat of frost has passed.
Potting and Repotting Blueberries
You should start growing blueberries in as large of a container as possible. If you see roots emerging from drainage holes or the top of your container, it’s time to repot into something larger. Choose a container that comfortably fits the root ball. Fill your container with fresh potting mix or a soilless medium of equal parts shredded pine bark and sphagnum peat moss. After removing the plant from its current container, gently shake off any excess soil. Replant the shrub at the same depth it was in its previous container. Keep the soil moist, but not soggy.
Overwintering
Blueberry bushes go dormant over the winter, and they’re generally hardy to the coldest conditions of their hardiness zones. However, they can be susceptible to fluctuating winter temperatures that trigger new growth. If your blueberries are growing in pots, it’s helpful to cover them in frost blankets to minimize freezing air and wind chills. To protect the bushes in the ground and maintain consistent soil temperatures, add a layer of mulch around them before the weather gets cold.
Common Pests and Plant Diseases
By far the biggest problem growing blueberries is keeping birds at bay. Placing bird netting over your blueberries or using a scarecrow can be successful if you have only a few bushes, but if you have a large blueberry patch, consider trying a bird deterrent that sends out a bird-in-distress call to repel birds. Insects to be on the lookout for include: scale, 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 rust (which can be treated with neem oil) along with 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 them in full sun, clean up any fallen debris, and replace the mulch annually so that fungal spores cannot overwinter in the area. If you experience these problems, you might need to use a fungicide labeled for use on edible plants. Some other common blueberry diseases to be aware of 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: 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 sign of an infestation is the blackening of 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 blight: Twig blight can start off looking very similar to canker. As twig blight progresses, it can affect the crown, smaller branches, and twigs, and it can also cause leaf spotting.
