Blueberries are popular shrubs for the orchard, but they have special requirements for soil and location. Like rhododendrons, the plants belong to the heather family and need a humus-rich, lime-free and evenly moist soil.
Cultivated blueberries are not descended from the native blueberry (Vaccinium myrtillus), but are the result of crosses of the blue huckleberry (Vaccinium corymbosum) with some other species. They are much larger-fruited than the native blueberries and, unlike them, have light-colored flesh. In terms of taste, cultivated blueberries are undoubtedly superior to their wild European relatives, but they also contain significantly fewer vitamins, minerals and secondary plant compounds than the latter.
Always plant blueberries with a partner
Although almost all cultivated blueberries are self-pollinating, you should always plant at least two different varieties, because then the fruit yield is much higher. The flowers open from the beginning of May, depending on the variety, and are pollinated by insects. Varieties like ‘Bluecrop’ and ‘Berkeley’ were bred in the USA. ‘Heerma’ and ‘Ama’ originate from Germany, but also go back to American varieties.
Location and soil requirements of blueberries
With the right choice of location and planting
you set the course for a high yield: blueberries grow naturally in moist bog meadows and in the undergrowth of sparse bog forests. The roots of the shrubs tend to spread shallowly in the ground, so you should dig a planting hole that is not too deep and has a large diameter.
If your garden soil is nutrient-rich and rather clayey, you will need to replace the soil in the planting hole with a loose mixture of sand and leaf or bark compost. Although blueberries are very frugal, you should mix a handful of horn shavings into the nutrient-poor humus so that the plants have some nitrogen available to grow.
Planting blueberries: step by step instructions
Prepare the planting hole
Dig the pit about 40 centimeters deep and 80 centimeters wide (16 x 32 in). The length depends on the number of plants: shrubs need about 70 centimeters (28 in) apart. Fill the pit to a hand’s width below the edge with acidic rhododendron or bog bed soil.
Plant the blueberry
Remove the blueberry from the pot and place it deep enough into the substrate so that the root ball still protrudes about five centimeters (2 in).
Spread bark mulch
Spread coarse bark mulch around the shrub and cover the rest of the bed with it as well. Alternatively, you can use for this purpose even chopped coniferous branches.
Watering the blueberry
Around the bale mound about 10-15 centimeters (4-6 in) high mulch. Then water the blueberry with lime-free water, preferably from the rain barrel. Continue to keep the bed well moist, from the second year of standing, you should work in some rhododendron fertilizer each spring.
Like most heathers, blueberries are very sensitive to planting too deeply, as their roots die very quickly when oxygen is depleted. Therefore, plant the plants only deep enough so that the top edge of the pot or soil ball protrudes a finger or two from the soil, and mound the entire root area with bark mulch or bark compost. This will simulate the natural raw humus cover of the soil in the blueberry’s natural habitat. Caution: As soon as the lime content in the soil increases even slightly, the shrubs show yellow leaves and hardly grow at all, because the lime interferes with the iron absorption of the roots.
How to plant blueberries in spring
When planting blueberries in the spring, be sure to remove all blossoms. By doing this, you will prevent the bushes from going to waste energy when it comes to fruiting, even though they have not yet grown in properly. Good watering is not only important right after planting. In the following years, too, you must make sure that the soil is evenly moist from the time of flowering at the latest. Otherwise, the berries will remain small and fall off prematurely.
Water all blueberries with rainwater or very low-lime tap water only. Because blueberries need to be well watered in dry summers, hard water can otherwise cause a lot of lime to build up in the root zone and, over time, cause growth problems called lime chlorosis.