Red, plump tomatoes often appear in the home garden, prized for their use in cooking and their great taste fresh off the vine. However, growing tomatoes can be challenging. Many diseases and conditions occur in tomatoes if gardeners do not work actively to maintain ideal growing conditions. One common disorder in tomatoes is blossom-end rot, caused by a lack of calcium. Adding calcium helps prevent this condition from occurring.
Foliar calcium sprays contain calcium nitrate or calcium chloride. These help prevent or correct low calcium levels in tomato plants. Some soil amendments also contain calcium. An example of this is high-calcium limestone, applied to correct the soil pH at least two months prior to planting. Choose gypsum instead of limestone if the soil pH level is not below 6.0. Sprays and soil amendments are available at your local gardening center.
Applying foliar sprays at the rate of 4 tablespoons per gallon of water up to three times per week is adequate for plants already showing signs of calcium deficiency. Start spraying when blooming of the second fruit clusters starts and continue until harvest. The amount of soil amendments to use will depend on the results of a soil test. The results should give specific instructions regarding the ideal amount to add to the soil.
Using calcium supplements for tomato plants helps prevent blossom end rot from appearing by providing extra calcium to plants. It also helps prevent the condition in fruits not yet affected by the lack of calcium; however, it will not correct the damage already done. Affected fruit must be removed, unless damage is only minimal and the fruit can be saved for harvesting.
Most soil contains adequate amounts of calcium, though testing prior to planting offers detailed information regarding the levels of calcium and other nutrients in your soil. Keeping tomato plants adequately watered reduces calcium deprivation. Tomato plants exposed to excessively wet or dry conditions cannot absorb calcium through their roots, leading to this problem even in soil with proper calcium levels. Tomatoes need a minimum of 1 inch of water per week, or the equivalent of 5 gallons of water. This keeps plants and fruit healthy.
Using calcium chloride sprays when temperatures reach 90 degrees Fahrenheit or higher causes chemical burns on tomato plants. In these weather conditions, avoid damaging plants by using calcium nitrate instead.