My Tomato Blossoms Won't Set

Temperature and Humidity

• Environmental conditions play a large role in whether tomato plants set fruit. According to Rutgers University, the best conditions for flower pollination occurs when daytime temperatures fall within 70 to 85 degrees Fahrenheit, nighttime temperatures range from 55 to 75 degrees and humidity levels range from 40 to 70 percent. Very warm or cool temperatures results in sterile pollen and flower drop. High or low humidity leads to sticky pollen that doesn’t shed or dry pollen that will not adhere to the stigma.

Pollination

• Tomato plants are pollinated by wind and insects – without them, pollination will not occur and flowers will drop. Ensure your tomato plants set fruit by pollinating flowers yourself. Washington State University suggests tapping or shaking the tomato plant to release pollen; do this in the middle of the day when temperatures are warm and pollen is active.

Moisture and Nutrients

• Ample water and nutrients are important for fruit set on tomato plants. Because of deep roots, tomato plants need plenty of moisture. If grown in containers, be sure to check for dry soil every day. Too much nitrogen during flowering could result in flower drop. University of Missouri Extension suggests supplying the soil before planting with a complete fertilizer, high in phosphorus and low in nitrogen. Add more nitrogen throughout the season as fruits develop and after harvest.

Planting Site

• For bountiful flowers and fruit, provide your tomato plants with well-drained soil that has a pH range of 6.5 to 7.0. Space plants 24 to 36 inches apart for good air circulation; proper spacing reduces the chance for fungi and diseases to settle in. For larger tomato plants, provide at least 36 inches in between plants.