Cultivating the blueberry plant in the family orchard requires some attention not to be underestimated. The blueberry is a wild fruit, the most cultivated species in Italy being called the American Giant Blueberry. This species encompasses various varieties. This cultivation can be very satisfying even for the most inexperienced, both in terms of individual plant yields and fruit quality.
However, to cultivate healthy and lush plants, it’s necessary to understand their cultivation needs and all the necessary care. Let’s take a look at all the required care, from planting to pruning operations.
The Blueberry Plant, Botanical Identification, and Existing Species
The blueberry plant (Vaccinium) belongs to the Ericaceae family. The most cultivated species is called Vaccinium corymbosum, also known as the American Giant Blueberry, and that’s what we’ll focus on. However, there are about 130 varieties of blueberries, some cultivated and others growing spontaneously in the woods. Let’s see the main ones:
- Vaccinium myrtillus, or European blackberry, a spontaneous species in Europe. In Italy, it is found in the Alpine arc up to 2000 m, as well as in Abruzzo.
- Idaea, or red blueberry, another spontaneous European species. Small and evergreen, it produces red, acidic, and bitter berries. In Italy, it’s found in the Alps and northern Apennines.
- Uliginosum, or blueberry, spontaneous in Europe but less common in Italy. A small deciduous shrub that produces bluish berries, pruinose, tasteless, with colorless juice.
- Macrocarpon, or American cranberry. A cultivated species but also grows spontaneously in America, producing large red berries.
- Angustifolium, or lowbush blueberry. Cultivated in Europe, spontaneous in North America. Compact (up to 50 cm). Produces pruinose, blue-colored, sweet, and fragrant berries.
Moreover, the blueberry should not be confused with another widespread spontaneous plant, especially in Southern Italy and the Islands, namely the myrtle (Myrtus communis), of the Myrtaceae family.
Botanical Characteristics of the Blueberry Plant
The American Giant Blueberry plant is deciduous, shedding its foliage during the vegetative rest period. It has an erect shrubby habit, with shoots (suckers) growing from the base or collar of the plant. It has a shallow and expansive root system with two types of roots. The large ones that the plant uses to store reserves and anchor itself to the soil, and the fine ones, useful for absorbing nutrients quickly from the soil. The very expansive root system affects irrigation, which must cover a wide portion of the ground around the plant. The flowers of the American Giant Blueberry are white or pinkish, shaped like a small bell facing downward, grouped in corymb inflorescences. The American Giant Blueberry plants are self-fertile but benefit from cross-pollination. The fruits, blueberries, are globose berries with bright blue color, a light pruinose layer making them clearer. The pulp is soft, whitish-greenish, with a taste between sweet and sour, more or less intense.
Varieties of American Giant Blueberry
There are several varieties of the American giant blueberry that can be cultivated in the family orchard. Each of these has different characteristics, especially in terms of contained substances. Let’s see what these varieties are.
- Duke, an early maturing variety. It withstands spring cold snaps well due to late flowering, a crucial characteristic for blueberry plants. It’s highly productive, yielding fruits of excellent quality with an aromatic fragrance and medium size. The blueberries are light blue, with a balanced taste between sweet and tart.
- Spartan, an early maturing variety with good resistance to spring cold. It produces very large blueberries with compact flesh and pleasant flavor.
- Bluecrop, an intermediate maturing variety. It ensures consistent and high productivity, offering excellent-sized fruits. The blueberries are light blue with a somewhat elongated shape.
- Brigitta, a semi-late maturing variety, vigorous and highly productive, yielding fruits of excellent quality that can be stored for an extended period, extending the consumption period.
- Jersey, a variety with very elliptical, dark green leaves. It produces large, very sweet blueberries upon complete ripening, occurring between late June and early July.
The blueberry plant is usually grown in hilly and low mountain areas. It has excellent cold resistance, enduring temperatures as low as -30 “C. This happens if the young shoots are well lignified during the growing season. Blueberries are more susceptible to late spring cold snaps, especially during the flowering phase. Intense late spring cold can compromise the subsequent fruit set. Therefore, the plant needs to be protected from frost more in spring than in winter, with timely interventions when critical conditions arise. A good idea is to shield the plant with frost-protection covers like these ones. Finally, the plant prefers full sun exposure but sheltered from winds, such as through the use of windbreak hedges. High temperatures are important during the fruit ripening phase to increase sugar content.
Soil and Correct Acidity
Blueberries are demanding in terms of soil. They thrive in acidic conditions, with a pH level between 4 and 5. With pH values above 5.5-6, the plant’s growth and production may be compromised. Unsuitable soil types often lead to absorption problems and deficiencies, especially iron chlorosis, resulting in rapid leaf yellowing. The soil doesn’t need to be very deep; it’s more important to lack limestone and have a good supply of decomposed organic matter. Additionally, the soil structure should be loose to prevent waterlogging and facilitate water absorption. Before starting a blueberry cultivation, it’s wise to perform a soil pH analysis to check the acidity level and, if necessary, make corrections. An approach to adjust acidity is to amend the soil with acidic peat. This can be done during soil preparation or at planting time. Acidic peat can replace mature manure during planting. A good organic acidic peat can be found here. Remember, acidic peat is readily available in nature. For instance, you can find it by taking soil from under an old chestnut tree. Another product used to acidify the soil is pelleted sulfur, allowed in organic farming. However, it’s advisable to follow the manufacturer’s instructions for dosing.
Blueberries can be propagated by seeds or woody or semi-woody cuttings. Established plants of varying ages, from 9 to 15 months, are available in the market. These plants are sold in plastic pots with soil or as bare-rooted plants. Typically, the containers are small, causing root constriction in blueberry plants. Before planting, it’s advisable to untangle and spread out the roots. This promotes establishment and future growth. Another consideration after planting is timely irrigation. Also, observe the plant you’re purchasing carefully. Young blueberry plants in the market might have several branches originating from the stem. During transplanting, it’s recommended to prune the crown lightly, removing excess branches, especially the weak and thin ones. The optimal planting periods are autumn for bare-rooted plants and late winter/early spring for potted plants. The optimal planting distance for a blueberry bush is 2-2.5m between rows and 1.5-2m within rows. These distances may vary based on the chosen variety’s vigor. We recommend selecting different varieties to have a staggered harvest and encourage cross-pollination.
Irrigation and Mulching
When growing blueberries, significant attention should be given to irrigation and mulching. As previously mentioned, the plant has a shallow and extensive root system. It also has a high water requirement during vegetative and fruit maturation phases. Natural precipitation isn’t always sufficient to ensure adequate water volume. Therefore, setting up an irrigation system is necessary. In blueberry cultivation, an effective system for uniformly watering the soil is using a double irrigation hose, placed 25 cm apart. The plants are positioned between the two hoses to ensure uniform and broad soil wetting. Mulching is also necessary to reduce water needs and keep weeds at bay. Weeds are problematic as they compete for water and nutrients. Many opt for artificial mulching using fabric sheets (such as these). These sheets are pierced at desired intervals and laid on the soil before planting. They have the advantage of long-term durability and complete weed elimination but come with a higher cost. The alternative is traditional natural mulching, which, for blueberry plants, is best done using bark, pine needles, and old peat mixed with leaves. These materials acidify the soil.
Organic fertilization should be done in autumn or late winter before vegetative growth resumes. It’s recommended to use mature manure spread between rows, at the plant’s base. If the soil has had its acidity adjusted, acidic peat should be added to the manure to maintain the right pH. When using fabric mulching sheets, fertilization can be challenging. In this case, the sheets need to be moved to distribute the required organic matter.
Training Form and Pruning
For the blueberry plant, the ideal training form is the free bush, without supports. The bush should consist of 5-6 productive branches alongside 1-2 necessary shoots for renewal. Pruning interventions aim to regulate production while ensuring plant renewal. It’s essential to intervene in a balanced manner as drastic cuts unbalance the plants and enhance vegetative growth. Conversely, lack of pruning, especially in adult plants, ages the branches prematurely and compromises production. Untreated branches do not adequately bear productive buds. In the first year of the plant’s life, intervention involves removing the flowers to favor the formation of the root system. In subsequent years (from the first to the third), pruning is quicker. It primarily involves opening the plant by eliminating branches and shoots growing in the central part. Excessive basal shoots are also removed. The goal is to form a blueberry plant with 5-6 branches, eliminating 1-2 old ones every year, replacing them with a couple of vigorous 1-2-year-old shoots. On average, about 1/3 of the old wood is removed.
Harvest Time and Uses
Blueberries are harvested from June to August, depending on the variety and cultivation area. Fruit ripening is staggered, and a plant can produce for up to 4 weeks, with breaks every 5-10 days. An indicator of fruit ripeness is the berry’s coloration, which should be uniform and complete. Ripe fruits of the giant American blueberry are eaten as they are, perhaps with the addition of lemon and sugar. They are excellent for making jams, jellies, and syrups. Fermenting the juice produces a somewhat alcoholic beverage: the famous blueberry wine. From this, through a distillation process, an excellent grappa is obtained, very popular in Germany and France.
Biological Pest Defense
For the biological pest defense of the blueberry plant, much attention should be given to aphids. These pests appear in the spring months. Colonies mainly concentrate on shoot tips, which can deform and hinder growth. Aphids also produce honeydew, which soils the fruits and causes sooty mold, reducing the product’s quality. To combat aphids, natural macerates are recommended, such as those of garlic or nettle. In the case of severe infestations, pure Marseille soap can be used, found here. Other problematic insects in blueberry cultivation are the scale insects and the black vine weevil. For further information on these insects, refer to specific posts.