Help ensure a healthy harvest with Rot-Stop Tomato Blossom End Rot Concentrate from Bonide. 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 including tomatoes, cucumbers, melons and peppers to produce healthy, blossoming 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. This concentrated solution arrives ready to mix with water. To use, mix 2 oz of Rot-Stop per gallon of water and apply to affected plants to the point of run-off. Apply to affected plants every 5-7 days as needed. For full use instructions, please see product label. Rot-Stop can be used both indoors and outdoors on listed plants.