What Is in Tomato Bloom Spray?

Temperatures

• Extremes of temperatures like multiple successive cold nights below 55 degrees can inhibit fruit setting. So can hot days when temperatures reach in excess of 90 degrees with nighttime temperatures above 75 degrees. Optimal temperatures for setting fruit is between 70 and 85 degrees during the daytime. Hot days or cold nights drain energy from the plant, causing it to spend energy surviving rather than setting fruit. Avoid planting tomatoes too early after cool nights are past. You can plant early varieties that are more tolerant of cold. In the South, heat-tolerant varieties set fruit at temperatures above 85 degrees.

Pollination Problems

• A lack of active insects like bees and butterflies can reduce the numbers of blossoms that successfully set. Tomatoes are self-pollinators, at between 40 to 70 percent humidity. In extremely dry weather, pollen may not stick to the pistil and pollinate the flower. Heavy rains or high humidity can cause pollen to adhere to the anther and fail to release pollen, preventing self-pollination. Stimulating pollination manually by shaking the plants, can spread pollen. Planting flowers near your tomatoes will attract bees and other insect pollinators that can help. In dry weather, misting helps pollen stick and blossom sprays may make plants more receptive to pollination.

Fertilization

• Tomatoes need a lot of nitrogen to support leaf growth, but too much nitrogen without sufficient phosphorus and potassium can cause the plant to spend its energy growing leaves instead of setting fruit. Don't over-fertilize, and use a tomato-specific fertilizer blend.

Irrigation

• Over-watering or drought can stress tomato plants and inhibit fruit setting. Water deeply twice a week with 1 to 3 inches of water depending on rainfall. Deep water stimulates healthy root growth, which supports fruit setting.

Overproduction of Blossoms

• If a healthy tomato plant produces too many flowers, they will compete with each other for limited amounts of nutrients from the root system. The competition may weaken the flowers and some may not survive. Some gardeners will pinch off weak or malformed flowers, but in most cases the strongest blooms will pollinate and weaker ones will fall off on their own, thereby selecting the flowers that will produce the best fruit.

Blossom Spray

• By spraying with a natural plant hormone spray, blossoms can be stimulated to set fruit despite the presence of stressors in the environment. The hormone stimulates the production of larger, meatier tomatoes with fewer seeds. Tomato blossom spray is a natural product that doesn't cause any environmental side-effects. Blossom set sprays contain some combination of plant nutrients like nitrogen, phosphate, potassium, calcium citrate or zinc. Some contain beta-napthoxyacetic acid or the plant hormone Cytokinin or Kinetin. Sprayed on the backs of open blossoms, the spray promotes flowering and increases fruit setting. Sprays containing calcium also reduce blossom end rot. Blossom end rot specific spray is not applied until fruit appears and works to strengthen the skin of growing tomato fruit with added calcium absorbed through leaves and fruit.