Do Blueberries Need Sunlight? A Detailed Guide to Blueberry Light Requirements
SummaryThe growth speed of blueberries is directly affected by light. Too much light or too little light will slow down blueberry growth and may even cause them to die, so blueberry cultivation requires moderate light intensity. The light requirements of blueberries vary according to their variety. For most blueberry varieties, a light intensity of only above 1000 feet is enough to meet their basic growth needs, and the specific light intensity still needs to be adjusted according to the different varieties.
Light requirements for blueberry growth
The growth speed of blueberries varies according to light intensity. Stronger or weaker light will both affect blueberry growth and may even cause them to die, so planting blueberries requires moderate light intensity.
Different varieties have different requirements for light intensity. For most varieties, a light intensity above 1000 feet can meet their basic needs, but if the light intensity is below 650 feet, the photosynthetic capacity of some varieties will decrease, such as lowbush blueberries. If the light is above 1000 feet and the light intensity is increased further, the number of their flower buds will increase.
When the light intensity is less than 2100fc, the fruit ripening time of lowbush blueberries will be delayed, and lower light will affect the fruit ripening rate and sugar content during the harvest period.
Excessive ultraviolet light will affect blueberry growth and fruit development. Generally, on a normal sunny day, the ultraviolet light intensity at the ground is 1.74 watts/sq m. If 24-44 uv-B units of ultraviolet light are used to treat protruding blueberry fruit, the single fruit weight will decrease. Using 24 uv-B units of ultraviolet light on the berries will prevent them from producing wax. When ultraviolet light is 4 times higher than normal light, sunburn-like scars will appear on the surface of blueberries. Ultraviolet light will inhibit the growth speed of blueberries and lower the number of flower buds, so when planting blueberries, be sure to choose a place with relatively strong light intensity to ensure normal blueberry growth.
Temperature requirements for blueberries
When planting blueberry trees, choose a sunny and moist place. They can tolerate high temperatures; even under the summer sun at around 40°C they will not be killed by the sun. As long as they are watered sufficiently, they can grow under high temperatures of 40-50°C. However, if the light is insufficient, blueberries will stop growing, and even if they bloom, they will not bear fruit. In summer, water blueberry trees every day, but do so in moderation. Do not water too much and cause waterlogging, which can cause root rot in blueberry trees.
After the blueberry seedlings grown in pots are planted, they need to be placed indoors for about 7 days in a place without direct sunlight but with ventilation to acclimate. After 7 days, they can be moved outdoors for normal planting and care.
When the temperature is 20-30°C, the photosynthetic capacity of blueberry trees reaches its strongest. If the temperature is below 20°C or above 30°C, the photosynthetic capacity will decrease noticeably. To ensure their normal photosynthetic capacity, in spring place them in a sunny and wind-sheltered place to provide them with a higher growing temperature, and in summer place them in a place with good ventilation to prevent excessively high temperatures from harming the trees.
Air temperature and soil temperature have a certain effect on the growth speed of blueberries. When the temperature rises from 18°C to 30°C, the number of rhizomes of lowbush blueberries will increase noticeably and their growth speed will accelerate. When the soil temperature rises from 13°C to 32°C, the growth speed of highbush blueberries will accelerate. When the soil temperature is below 20°C, the branch spacing of highbush blueberries will spread out. As the temperature rises, the tree body will grow upright and tall. If the temperature is below 8°C and the soil temperature is 9°C, the blueberry root system will stop growing. 15.6°C-26.7°C is the most suitable growing temperature for blueberry trees.
During the planting process, the time for protecting the seedlings from cold must not be too early or too late. Generally, it is done when the temperature stabilizes below 5°C.
Chilling requirement
For blueberry trees to bloom and bear fruit normally, the growing environment must maintain a temperature below 7°C for 800-1200 hours. This is called the chilling requirement. Different varieties have different chilling requirement times. For example, northern highbush blueberries need to grow for about 800-1200 hours in an environment of 0-7°C. If the chilling requirement time is not reached, blueberry trees will still bloom, but they will not bear fruit.
In winter, potted blueberries do not need to be cared for indoors with heating or warmth-retaining functions. Generally, place them in a garage, warehouse or shaded balcony where the temperature is kept below 7.2°C. If blueberries are grown on a balcony in the Jiangnan region, they can be placed directly on the balcony in winter.