Perhaps in the past you made the decision to plant your own blueberry bushes, inspired by visions of steaming stacks of blueberry pancakes drizzled with homemade blueberry syrup. You probably picked what you thought was the perfect spot to plant, with rich soil and lots of sun. And you likely worked the soil well, mixing in lots of organic material and fertilizer. Then you brought your precious new plants home from the nursery, carefully planted them, and spent the winter dreaming of fresh berries. When spring finally arrived, you eagerly watched as your blueberries pushed out fresh green leaves — only to yellow, drop, and die.
If that outcome sounds all too familiar, you’re not alone. At one time, gardeners and horticulturists alike believed blueberries would never be domesticated. The berry that Native Americans considered a gift from the Great Spirit, that colonists came to rely on to add sweetness and variety to their diet, and that drew people into swampy barrens each summer consistently refused to thrive when transplanted to gardens or cultivated fields, no matter how carefully it was pampered.
The cultivation of blueberries remained a mystery until the early 1900s, when U.S. Department of Agriculture (USDA) botanist Frederick Coville joined forces with New Jersey cranberry farmer Elizabeth White to grow the first commercial blueberries.
Prior to their collaboration, Coville experimented by growing plants in glass to study how their roots grew. During these experiments, he discovered why blueberries had always failed in cultivation, and how to correct the problem. When White read Coville’s findings, she promptly wrote him to offer a collaboration: If he agreed to plant an experimental plot in New Jersey, she’d supply the wild blueberry genetics and land to grow them. With her agricultural experience and his botanical knowledge, they succeeded in bringing blueberries to the mainstream market for the first time in history.
The secret to growing blueberries is in the soil. Blueberries grow and thrive in conditions that outright kill most other plants, meaning your rich loam is lethal to blueberries, especially if you’ve added lime to your garden, or the soil’s pH is naturally alkaline. Blueberry bushes thrive in areas such as pine barrens, bogs, and glacier-scoured clearings, in soil that’s thin, sour, and bony. As shallow-rooted plants, they prefer their soil moist but well-drained, with plenty of organic material that’s nutrient-poor.
The key to good blueberries is soil acidity, which is measured on the pH scale. The pH scale runs from 0 (battery acid) to 14 (lye), with 7 being neutral. It’s a logarithmic scale, meaning that each full step away from 7 is 10 times as acidic or alkaline.
Most gardeners consider loamy soil with a pH of 6.5 to be ideal, but for blueberries, that means slow death. They need soil with a pH of 4.5 to 5, roughly comparable to tomato juice or a cup of black coffee. For a more accurate way to measure soil pH, invest in a pH meter or litmus test kit. A basic meter will cost about $10 — well worth it for an abundant blueberry harvest. Also consider sending a soil sample to your local extension office, along with a request for specific advice on growing blueberries; the agent can make amendment suggestions based on your soil’s exact chemistry.
Assuming your soil isn’t acidic enough, which is a fair bet in most of the country, you can amend soil acidity with additions of milled peat, spent coffee grounds, and in extreme cases, elemental sulfur, mixed into the soil at planting time. Organic fertilizers specifically formulated for hollies, azaleas, and rhododendrons can also be used to help acidify the soil, when used as instructed. You can continue to add acidifiers as top-dressing mulches some seasons after planting, but, as with most chemistry changes, you need to go slowly and retest often.
If your soil is heavy and poorly drained, consider growing your blueberries in raised garden beds. The added height of a raised bed will help to drain excess water away from the shallow roots, while the added organic material will retain enough moisture to keep them happy. The defined borders of raised beds also help to contain soil amendments and acidifiers to where you need them.
If you garden in the West or in limestone country where soils are naturally alkaline, you’ll likely find changing your soil pH to be almost impossible, so you may need to take a different approach to growing blueberries. Instead of planting directly in the ground and constantly struggling against the native soil’s chemistry, plant your blueberries in containers with soil you’ve custom-mixed. You can use wooden floored and sided beds or large pots. Don’t use concrete planters or cement blocks; they contain lime, which will leach into the soil and decrease its acidity.
Planting, Picking, and Pest Control
Whether you plant in the ground or in containers, you’ll need to select a spot in full sun, with good moisture or a reliable watering system, and plenty of airflow. Full sun will produce the sweetest berries. Space your in-ground bushes at least 5 feet apart, so you can easily walk around each one to prune and harvest. If planting in rows, allow at least 6 feet between the rows. Mulch the entire area when you plant, using your choice of organic material, such as leaf mold, compost, or pine straw. Mulch will eliminate competition from weeds and help contain fungal disease spores.
Over time, the mulch will break down and feed the soil, so plan to replenish it each year. Test the soil pH at the same time you mulch, at least every other year, and adjust the chemistry accordingly. Feed blueberry shrubs lightly each spring with an organic fertilizer formulated for acid-loving plants, and if necessary, add acidifiers.
Plan to prune your bushes in late winter or early spring. Make all the cuts as close to the ground as possible, keeping airflow in mind as you prune. Blueberries are woody, suckering shrubs without a definite trunk, and require appropriate pruning. First, remove any dead, damaged, or unhealthy-looking branches. Before cutting more, remember that blueberries fruit on old wood, from 1 to 6 years old. Wood older than 6 years needs to be removed. By the time a blueberry branch is 6 years old, it has grown to about an inch in diameter, so plan to cut out only the heaviest branches. Cut them as close to the ground as possible. After you’ve pruned the heavy branches, use a bypass hand pruner to remove any crowded, inward-turning, or crossing branches. When you’re finished, the bush should be about 1/3 to 1/2 as full as when you started.
For the best flavor, let your blueberries hang on the bush until they’re fully colored, as they don’t continue to ripen once they’re picked. In fact, waiting a day or two after they turn completely blue improves their flavor immensely. A fully ripe blueberry will “slip” or fall from its stem with the slightest pressure. As you pick, cup each cluster lightly in your hand and jostle them gently, allowing the ripest ones to slip into your palm. This requires multiple pickings throughout the season, but it’s worth it.
Unfortunately, with this method you’ll be competing for your berries against their number one fan: birds. Birds absolutely love blueberries, and seem to always know when they’re ripe for the taking. Bird-scare devices such as scare tape, compact discs, and decoys are no match for the lure of fresh berries, and birds quickly learn to slip under netting draped over your bushes. Any gaps in the netting, no matter how small, will be used by feathered marauders. The only truly effective deterrent I’ve found is to build a walk-in cage or gallery around your bushes, covered completely with bird netting.
Blueberries can be affected by a few other pests and diseases, including blueberry maggots, gray mold, and mummy berry. To combat these issues, keep your plants healthy and maintain adequate mulch cover. Additionally, you can control blueberry maggots by hanging red, spherical traps set in your bushes early in the season; these capture adult flies before they can lay eggs. To create a homemade sticky trap, cover a bright red rubber or foam ball with a non-toxic compound for capturing insects, such as Tanglefoot.
Choose Your Blues
Three different species of blueberries are available to choose from: highbush (Vaccinium corymbosum), lowbush (V. angustifolium), and rabbiteye (V. ashei).
Highbush blueberries are the industry standard, and the most commonly available in catalogs and nurseries across the Mid-Atlantic states. They can reach 7 feet in height if not pruned, and do well in Zones 4 to 7.
Southern gardeners often have difficulty growing highbush blueberries because of heightened heat and humidity. Luckily, rabbiteye blueberries are well-suited to these regions, growing happily in Zones 7 to 9. Left to grow unchecked, rabbiteyes grow up to 15 feet, but can easily be kept at more manageable heights with judicious pruning.
Lowbush blueberries offer northern growers a wilder option. These “bushes” reach only 12 to 18 inches in height, but are loaded with small, intensely flavored berries. Most lowbush varieties are wild selections. They prefer the colder climates of Zones 3 to 7. Lowbush berries are typically harvested with a blueberry rake — a scooping tool with tines on the end. You can easily prune lowbush plants by mowing over older patches with a brush cutter. This renews the patch, but delays the next harvest by a year, so consider maintaining at least two patches at a time.
As with many bush fruits, blueberries are partially self-fruitful. Select two cultivars for cross-pollination, and you’ll be rewarded with more abundant, better-tasting berries, and a longer picking season. Contact your local extension office for selections that will do well in your area.
For a plant once thought impossible to cultivate, blueberries are surprisingly easy to grow — as long as you supply them with what they need to thrive. You’ll never regret the effort, especially when you finally have those buckets of berries you’ve been dreaming about!