Help ensure a healthy harvest with Rot-Stop Tomato Blossom End Rot preventer. The active ingredient, calcium derived from calcium chloride, corrects calcium deficiency in plants in your home garden. This product can be applied to a variety of plants in your garden including tomatoes, cucumbers, melons, and peppers to produce healthy, blossoming vegetable plants. End-rot can occur at any point of fruit development, use Rot-Stop to stop end-rot in its tracks throughout the plant's lifecycle. Apply to affected plants every 5 to 7 days as needed. For full use instructions, please see product label. Rot-Stop can be used both indoors and outdoors on listed plants.