You probably already buy blueberries, so why not grow your own? Photo: http://www.almanac.com
Blueberries (Vaccinium spp.) are a fruit of North American origin, but are becoming more and more popular around the world. In addition to being delicious and sweet, blueberry fruits are excellent for your health. The blueberry is one of the temperate fruits richest in antioxidants thanks to the abundant anthocyanins it contains. It is also rich in vitamins C and K, not to mention a host of other minerals and vitamins.
Blueberries were once very much a seasonal crop, but now, with blueberry farms being found in both hemispheres over a wide range of different climatic conditions, you can find fresh blueberries in supermarkets most of the year. If not, you can certainly find frozen blueberries in any season and also a wide range of blueberry products: muffins, yoghurt, jams, jellies, chocolate-covered blueberries and much more.
And many people from Eastern North America, where blueberries are particularly numerous in nature, can fondly recall family trips into the wild to harvest blueberries as a child.
Finally, if you garden, there’s a very good chance you already grow your own blueberries, but if not, you can certainly do so. In fact, it’s not even particularly difficult.
In Which Garden?
The classical way to grow blueberries is to plant them in the vegetable garden. After all, they are edible plants and fairly compact, right? But I’d like to encourage you to think of them in a new light: as edible plants that are also ornamental and to move them from the veggie bed into your home landscape. This fits in with the foodscaping trend that is all the rage these days and is so easy to do.
The blueberry is the ideal plant for foodscaping. With its dense, shiny, dark green leaves, its beautiful little white to pinkish bell-shaped flowers in the spring, its attractive summer berries and its flamboyant red leaves in the fall, it has everything a landscape plant needs. And if planted in a row, it even makes an excellent privacy hedge.
Which Blueberry Should You Grow?
There are actually many species of blueberries, but there’s only one, the highbush blueberry (Vaccinium corymbosum), that is really widely grown and easy to find in almost any nursery. And it’s probably also the easiest one for most gardeners to grow.
The highbush blueberry is a medium-sized shrub, reaching 6 to 10 feet (1.8 to 3 m) if you let it grow on its own, but is usually kept to 3 to 4 feet (90 to 120 cm) high and wide in landscape situations with the help of a bit of judicious pruning. This is the blueberry you see in supermarkets, with big bluish berries. It’s best adapted to moderate climates: hardiness zones 4 to 8.
The lowbush blueberry (V. angustifolium), native to the Northeastern United States and eastern Canada, is widely grown commercially, but not as easy to find in nurseries. Most blueberry farms growing lowbush blueberries actually count on wild plants, subtracting any competing vegetation so the wild plants can take over, although there are plenty of cultivars around that are more productive than the wild plants. Where you can find it in nurseries, it makes a great groundcover, many cultivars not reaching over 1 foot (30 cm) in height. Its fruits are small, but numerous and especially sweet. The lowbush blueberry is the hardiest of the commonly grown blueberries, adapted to zones 2 to 7.
Then there are the half-high blueberries, which as you probably guessed, are hybrids between highbush and lowbush blueberries. They’re intermediate in just about every way, from plant size (about 2 ½ feet/75 cm) to fruit size and even hardiness: zones 3 to 8.
All the above varieties need a long, cold winter, so gardeners in mild winter climates need to look elsewhere. Their best choice is probably the southern highbush blueberry, which is not a species, but was rather developed from crosses between the regular highbush blueberry (V. corymbosum) and such heat-tolerant southern blueberry species as evergreen blueberry (V. darrowii) and rabbiteye blueberry (V. virgatum; formerly V. ashei). Southern highbush blueberries are fairly new to the market and still rather hard to find, but, with their hardiness zone range of 7 to 9, they extend the range of where you can grow blueberries as far south as Northern Florida.
Another choice for mild climates is the rabbiteye blueberry (V. virgatum). It’s a tall blueberry easily reaching 10 feet (3 m) in height and likewise adapted to hardiness zones 7 to 9.
The Secret Is in the Soil
The great secret of blueberry cultivation is to provide it with a light, acid soil, with a pH of 4.2 to 5.2. A pH of up to 6 is acceptable, but production may be reduced. This much more acid than most other crops and in fact, most other ornamental plants. Rhododendrons and azaleas are among the few garden plants commonly grown in soil that acid.
That’s why the very first thing you should do if you want to grow blueberries is to have a soil test done. In some areas, soils are naturally acidic and no special treatment is required. Elsewhere, it may be necessary to add an acidifying soil amendment, such as garden sulfur or horticultural peat, to the soil to bring the pH down.
If your soil is not just “neutral” but out and out alkaline (a pH of over 7), it’s probably wiser to give up your plans of growing blueberries. It’s already very difficult to lower the pH of a naturally alkaline soil, but keeping it low is even more complicated. It will tend to creep back to its natural range. Another possibility is to grow your blueberries in containers using a naturally acid soil.
Where the soil is light or sandy, blueberries will be very happy. And planting will be a snap. Just dig a hole (a trench if you’re planting a hedge) 2 to 4 inches (3 to 5 cm) deeper than the height of the root ball. By placing the root ball in a hole of that depth and covering the lower part of its stems with soil, that will encourage the plant to produce a better root system.
On the other hand, blueberries have a hard time dealing with heavy clay soils. If that’s the situation in your garden, the best thing is not to dig a hole and replace the old soil with an amended lighter one (that can lead to rot). Instead, it’s better to plant blueberry plants on a raised mound, bringing in a light, acidic soil from elsewhere for that purpose. A mound about 3 feet (1 m) wide and 18 inches (45 cm) high would be perfect.
You can also mix a slow-release, all-purpose fertilizer into the soil at planting. Avoid so-called starter fertilizers or transplant fertilizers: rather than helping plants root, they often hinder root production!
There is no need to add commercial mycorrhizal fungi to the soil at planting. Blueberries do not enter symbiosis with the type of mycorrhizae generally offered in commercial inoculants, but instead need a special kind: ericoid mycorrhizae. The blueberries that you will buy are probably already naturally inoculated, but if you’re concerned they might not be, add a shovel of soil taken at the foot of a rhododendron, azalea, blueberry or other ericaceous plant: it will undoubtedly contain the missing mycorrhizae.
Even if blueberries can grow in partial shade, they’ll produce fewer flowers and therefore fewer berries. Full sun is usually best. Only in really hot climates with intense sun is partial shade the best choice. In colder climates, a sheltered location where snow accumulates is ideal.
Space highbush blueberries about 3 to 4 feet (90 to 120 cm) to give them enough space to grow while lowbush berries will make a nice groundcover if planted about 8 inches (20 cm) apart.
Water well after planting and keep the soil moist but not soggy afterwards. Always cover the soil with about 2 to 4 inches (5 to 10 cm) of mulch. Not only will that help maintain reasonable soil moisture, but it also largely eliminates the need to weed … and you don’t want to do any hoeing at the base of blueberries: they tend to produce a lot of very shallow roots and don’t appreciate disturbance. You can use the mulch of your choice: whatever is available locally at a reasonable price will do.
But what about the popular belief that pine needles make the best mulch for blueberries because they help acidify the soil? Well, pine needles really aren’t acidic. The belief that they are is an old myth that refuses to die. You can indeed use pine needles as mulch, but just don’t count on any acidifying action on their part.
It’s best not to let your blueberries produce the first year, or even the second if you started with very young plants. Wait until your blueberry plant is properly rooted before you let the plant bloom and produce delicious berries!
After a few years, starting pruning back older branches that are less productive so younger branches with better bearing potential have room to develop. You can do this in early spring.
Fertilize annually, perhaps with an acidifying fertilizer.
Once your blueberry plants are established, you can expect them to produce for 20 years and more.
Choose the Right Cultivars
Most blueberries are at least partially self-fertile, but produce much more when they receive pollen from other blueberry varieties. Ideally, you’d plant not one, but two other blueberry varieties close together: that ensures the best cross-pollination.
There are dozens of cultivars in every category and some may perform better than others in different regions, so consult a local nursery for their suggestions. ‘Patriot’, ‘Northland’ and ‘Bluecrop’ are popular and generally easy to find highbush varieties adapted to a wide range of conditions. ‘Pink Lemonade’ is one of the new blueberries with pink fruits if that tickles your fancy, while ‘Perpetua’ produces two crops a year: one in early summer, the other in fall.
Sometimes nurseries offer “combo pots” with three varieties of blueberries growing in the same container. That can be an excellent choice for those who only have space for a single plant.
So, what are you waiting for? Plant a blueberry (or two or three) without delay!