Three Major Conditions and Eight Key Technical Points for Growing Blueberries

Blueberries are named this way because the skin of this fruit is blue. Although blueberries are very small, their nutritional value surpasses that of other fruits. Regularly eating blueberries can not only fight aging but also improve eyesight. Blueberries are also relatively expensive on the market, and now blueberry-picking orchards are popular, where you can go and pick blueberries yourself, and growers are all eager to try. An introduction to the three major growing conditions and eight key growing techniques for blueberries.

I. Blueberry Growing Conditions

1. The soil pH at the orchard site should be 4 to 5.5, with the optimal soil pH being 4.0 to 4.8. The soil organic matter content should be 8% to 12%, and at least not lower than 5%. The soil should be loose, well aerated, moist but not waterlogged. If local rainfall is insufficient, an adequate water source is needed. To solve the problem of waterlogging in summer, the strip-style raised bed method can be used for cultivation.

2. After the orchard site is selected, deep plowing should be carried out 1 year before planting in combination with green manure incorporation, with a depth of 20 to 25 cm being appropriate, so as to deepen and mature the soil. If there are many weeds, a herbicide can be sprayed 1 year in advance to kill the weeds. For soil types that do not meet blueberry requirements, soil improvement should be carried out before planting to favor blueberry growth.

3. Adjusting soil that is too high in pH. Soil pH that is too high is an important factor limiting blueberry cultivation. Excessively high pH often causes iron deficiency chlorosis, poor growth, reduced yield, and even plant death. Applying 130 g of sulfur powder, its effect can last more than 3 years, and other soil types can refer to this dosage.

II. Key Technical Points for Growing Blueberries

1. Orchard site selection

The criteria for selecting soil types for blueberry cultivation are: slope not exceeding 10%; soil pH 4.0 to 5.5, preferably 4.3 to 4.8; soil organic matter content 8% to 12%, at least 5%; loose, with good drainage, moist but not waterlogged. If local annual rainfall is low, an adequate water source is needed.

After the orchard site is selected, apply 20 cubic meters of peat soil per mu and 7 to 10 cubic meters of decomposed cow manure, deep plow about 30 cm, then level the land, set up drainage ditches, and remove stones, grass roots, hard wood chunks, etc. After preparing the land, make raised beds, with a bed height of 25 to 30 cm and a width of 1 m, and plant one row in the middle of the bed.

2. Soil improvement techniques

When selecting an orchard site, not all soils are suitable for blueberry growth, and problems such as excessively high or low pH, overly clayey soil, and insufficient organic matter content often exist. Before planting, a comprehensive evaluation should be made of the soil structure, physical and chemical properties, etc., and unsuitable soil conditions should be improved to favor blueberry growth.

Soil pH that is too high is the main factor limiting the expansion of blueberry cultivation. Excessively high pH can cause iron deficiency chlorosis in blueberries, poor growth, reduced yield, and even plant death. When soil pH is greater than 5.5, the pH needs to be lowered: the most commonly used method is applying sulfur powder to the soil, and when applying sulfur powder it should be done one year before planting in combination with land preparation. Spread the sulfur powder evenly into the ground according to the calculated application rate, then deep plow and mix evenly.

Note: sulfur powder should be applied throughout the entire orchard, not only on the planting rows; covering the soil with sawdust or pine bark, applying acidic fertilizers, and applying crude tannic acid all also have the effect of lowering soil pH. Soil pH should be tested once a year, and if it is higher than 5.5 or lower than 4, it should be adjusted promptly.

 Improving soil structure and increasing organic matter

When soil organic matter content is <5% or the soil is clayey and compacted, organic materials need to be mixed in for improvement. This can not only increase soil organic matter but also lower soil pH. Rotted bark, sawdust, and organic materials can all be used as amendments to improve soil structure. Mixing organic materials into the soil can be done at planting together with digging the planting holes, generally by mixing orchard soil and organic materials in a 1:1 ratio and filling them into the planting holes, or by applying them throughout the orchard during land preparation in combination with deep plowing. Mixing organic materials into the soil can lower soil pH, increase organic matter content, improve soil structure, and favor the development of mycorrhizal fungi, thereby increasing yield and quality, and it has been widely used as a routine measure.

3. Seedling planting

Planting time

Planting can be done in either spring or autumn. Because northern regions need winter protection against cold, spring planting is generally adopted, but under protected cultivation conditions autumn planting can be used.

Digging planting holes

Dig the planting holes before planting. The size of the planting holes is generally 0.5 m × 0.5 m; after digging the planting holes, mix the orchard soil with organic materials and fill it back in.

Row and plant spacing

For highbush blueberries, the row and plant spacing is 0.6 to 1.5 m × 2 to 2.5 m; for half-high blueberries, 1 m × 2 m is commonly used; for lowbush blueberries, 0.5 m × 1 m is used.

Pollinator tree arrangement

Highbush blueberries need pollinator trees arranged, and some varieties are self-incompatible and must have pollinator trees arranged. Arranging pollinator trees for blueberries can increase the fruit-setting rate, increase single fruit weight, and improve yield and quality. Lowbush blueberry varieties can generally be planted as a single variety in an orchard. Pollinator trees can be arranged in a 1:1 pattern or a 2:1 pattern. The 1:1 pattern means the main variety and the pollinator variety are planted in equal amounts every 1 row or every 2 rows; the 2:1 pattern means 1 row of pollinator trees is planted every 2 rows of the main variety.

Planting

The best seedling age for planting is 2- to 3-year-old large seedlings. One-year-old rooted seedlings can also be planted, but the survival rate is low, and careful management is needed after planting. When planting, take the seedlings out of the nursery pots. If the seedling roots have already filled the nursery pot, it is best to gently break up the root soil before planting; if the roots have not filled the nursery pot, it is best to plant directly. The planting depth should be such that 3 cm of the original seedling soil ball is covered. After planting, cover with soil, press gently and firmly, and water thoroughly.

4. Soil management

Blueberry roots are distributed relatively shallowly and are fine, without root hairs, so the soil must be loose, porous, and well aerated. The main goal of soil management is to create soil conditions that allow good root development.

Clean cultivation

When growing highbush blueberries on sandy soil, clean cultivation is often used for soil management. Clean cultivation can effectively control competition between weeds and the trees and promote tree development; especially in the young tree stage, clean cultivation is very necessary. The depth of clean cultivation should be 5 to 10 cm.

Soil covering

The main functions of soil covering are to increase soil organic matter content, improve soil structure, regulate soil temperature, maintain soil moisture, lower soil pH, and control weeds. After the soil is covered, blueberry roots develop well in the decomposing mulch, causing the root system to extend more widely, expanding the surface for nutrient and water absorption, thereby promoting blueberry growth and increasing yield.

Covering can be done right after the seedlings are planted. Spread the mulch evenly over the bed surface, with a width of 1 m and a thickness of less than 10 cm, and then cover again each year with a 2.5 cm thick layer to maintain the original thickness.

5. Water management

Appropriate soil moisture is essential for blueberry growth, and insufficient water will seriously affect tree growth and yield. From bud break to leaf fall, the water required by blueberries is equivalent to an average weekly rainfall of 25 mm, and from fruit set to harvest it is 40 mm. Sandy soil has low soil moisture and low water-holding capacity, so irrigation facilities need to be set up to meet the water needs of blueberries. Commonly used irrigation methods include furrow irrigation, sprinkler irrigation, drip irrigation, and other irrigation methods.

6. Fertilization management

Organic blueberries are now advocated. If it is organic production, the entire blueberry production process does not allow the application of any chemically synthesized fertilizers. Therefore, before planting blueberries, sufficient organic materials must be applied to bring soil organic matter content to a relatively high level; each year, to supplement nutrient elements, farmyard manure, decomposed soybean cake or peanut cake, biogas slurry, etc. can be applied, and the application rate can be flexibly controlled according to the growth and yield of the blueberry plants.

7. Pruning techniques

The purpose of blueberry pruning is to regulate the conflict between reproductive growth and vegetative growth and to solve problems such as ventilation and light penetration. The general principle to master in pruning is to ensure high-quality fruit and high yield. Blueberry pruning can control yield, advance the maturity period, and increase single fruit weight, fruit quality, and commercial value. Pruning should be moderate and should be based on the intended use of the fruit; if it is for fresh market sale for raw eating, pruning should be heavier to increase commercial value.

The main pruning methods for blueberries include heading back, renewal pruning, thinning branches, pinching, tipping, flower thinning, fruit thinning, etc., and different pruning methods have different effects. They should be determined according to tree age, amount of branches, amount of flower buds, etc. During pruning, various methods should be used in combination to achieve the best results.

8. Other orchard management

Although lowbush blueberries and half-high blueberries among blueberries have relatively strong cold resistance, due to unsuitable low temperatures in some areas, freeze damage can still occur: the two most important types of freeze damage are winter shoot shriveling and flower bud freeze damage, and in special years this can even cause the aboveground part to freeze to death entirely.