Strawberry plants are sensitive to temperature, which significantly influences their growth, fruit production, and overall health. Understanding and managing temperature fluctuations is important for successful strawberry cultivation. These plants thrive within specific thermal ranges, and deviations can lead to reduced yields and diminished fruit quality.
Optimal Temperature Ranges for Growth and Production
For general growth and photosynthesis, an optimal range is between 15-27°C (59-80°F). Daytime temperatures are particularly important for photosynthesis, with 20°C (68°F) being optimal, though 20-24°C (68-75°F) is also effective. Consistent optimal temperatures contribute to better yield and fruit quality.
Nighttime temperatures are important for strawberry development. Cooler nighttime temperatures, between 10-15°C (50-59°F), promote flower initiation and improve fruit flavor and sweetness. A larger temperature difference between day and night increases total soluble solids (sugar content). Once plants begin to bear fruit, a slightly cooler range of 15-16°C (59-60.8°F) is ideal for maturation.
Cold Temperature Effects and Protection
Strawberries are perennial plants that undergo dormancy as temperatures drop, with flower buds developing during this period. Strawberries require a specific number of “chilling hours” to break dormancy and ensure proper flower and leaf development in the spring. This chilling period is accumulated hours between -2°C to 7°C (28-45°F). If plants do not receive enough chilling, flower buds may open unevenly or not at all, reducing yield.
Frost damage poses a risk to strawberry flowers and developing fruit. Open blossoms are particularly sensitive, becoming damaged at 0°C (32°F), while tight buds can tolerate temperatures as low as -6.6°C (20°F). Frost injury causes the center of the flower to blacken, even if petals appear unharmed.
To protect plants from cold, methods include applying mulch, such as straw, to insulate crowns and moderate soil temperatures. Row covers shield plants from frost. Overhead irrigation can also be used for frost protection, but it requires continuous application until temperatures rise above freezing.
Warm Temperature Effects and Management
Excessively warm temperatures can negatively affect strawberry plants, leading to heat stress and reduced productivity. Temperatures above 28-30°C (82-86°F) can cause strawberries to enter thermal dormancy, where vegetative growth continues but flowering ceases. High temperatures reduce fruit size and weight, and impair fruit coloration and quality. Sunscald, appearing as bleached or water-soaked lesions on fruit, can occur with excessive sunlight exposure.
To mitigate heat stress, provide shade with shade cloth during the hottest parts of the day. Ensuring adequate watering is important, as moisture helps cool the root zone and supports the plant’s transpiration process, which is its natural cooling mechanism. Frequent, short irrigation intervals during hot periods can cool the root zone without oversaturating the soil. Growing strawberries in containers offers flexibility, allowing them to be moved to shadier locations when temperatures rise.
Temperature Guidelines for Planting
The success of new strawberry plants largely depends on appropriate soil and air temperatures during planting. Strawberries establish best when planted in early spring as soon as the soil becomes workable. The ideal soil temperature for planting is between 7.2-10°C (45-50°F), with the lower end being suitable for bare-root plants and the upper end better for plugs and transplants. Planting during this cooler period encourages strong root growth before the plant focuses energy on foliage.
While bare-root plants can tolerate cooler conditions and light frost, it is advised to plant them when daytime temperatures are above freezing, ideally between 7.2-10°C (45-50°F). For bare-root plants, it is also important that the crown remains above the soil line during planting. Soil temperature is a more reliable indicator than air temperature for planting time, as it fluctuates less.