1. Lack of nutrients: Strawberries need adequate nutrients to stay healthy. If the soil is deficient in certain nutrients, such as calcium and boron, strawberries may suffer. If strawberries are deficient in calcium, the surface of the fruit may be covered with dense seeds, the fruit tissue hardens, the fruit is slow to expand, or even brown and stiff. If the lack of boron, strawberry flowers may be small, poor pollination, low fruiting rate, small fruits, more seeds, more verrucous or with deformities.

2. Physiological reasons: Strawberry blackening can also be caused by physiological reasons. If the strawberry in the flowering period encountered low or high temperatures, high humidity, or spraying pesticides and other reasons, may lead to poor pollination and fertilization, the formation of dead seeds, or do not secrete to make the receptacle expansion of the hormone, resulting in the fruit does not expand. Insufficient soil nutrients, too much fruit, poor plant growth, poor root absorption of water and nutrients, etc., can also lead to inadequate supply of nutrients, the formation of black small stiff fruit.

3. Disease: Blackened strawberries can be caused by disease. Gray mold and leather rot are two common strawberry diseases. Gray mold usually occurs in large quantities at the time of flowering, and the diseased fruit becomes hard and brown, and eventually stops growing. Leather rot has similar symptoms to gray mold, but without the gray mold layer.

If your strawberries are turning black, it is recommended that you take some steps to improve the situation. For example, control the ambient temperature, maintain proper humidity, prune the blackened parts in time, and pay attention to fertilization. If the problem is serious, consider consulting a professional or horticultural expert for more detailed advice and solutions.