Plant Food With Calcium for Tomatoes

Agricultural Lime

• Calcitic and dolomitic lime (CaCO3) are ground limestone agricultural amendments. They are naturally occurring and in addition to supplying calcium, they improve acidic soils by increasing the pH. Till lime into the soil several weeks before the beginning of the tomato season to allow time for calcium to become saturated with water for plant absorption. Always test soil pH before applying lime to make sure that the pH adjustment is necessary. Tomatoes thrive in slightly acidic conditions, so avoid adding too much lime. Apply lime once yearly if necessary, according to pH testing.

Gypsum

• Gypsum (CaSO4) is a naturally occurring, water-soluble calcium and sulfur mixture that doesn't change soil pH like agricultural lime. Apply gypsum before the tomato season begins, following a soil test indicating calcium deficiency. Although plants may have symptoms of calcium deficiency, a soil test is necessary to determine a deficiency in the soil as opposed to calcium deficiency caused by conditions that prevent the plant from absorbing calcium.

Calcium Nitrate

• Calcium nitrate, Ca(NO3)2, is a water-soluble nitrogen and calcium fertilizer suitable to tomato cultivation. Once plants begin to bloom, this fertilizer can be substituted for other nitrogen fertilizers until fruit is the size of a golf ball. This nitrogen and calcium mix helps the plants to maintain balance between leafy growth and fruit development. Apply as a water mixture to the root zone of the tomato plant. Foliar sprays are ineffective in delivering calcium, because calcium cannot be absorbed through the leaves and delivered to the fruit.

Maintaining Calcium Availability

• Following calcium amendment application, it is important to provide growing conditions that make calcium uptake possible by the tomatoes. Moisture is the key element that determines if plants can access soil calcium or not. Maintain soil moisture so that soil can be formed into a ball but is not soggy. Limit the amount of nitrogen and potassium delivered to the plant, as these nutrients compete with calcium for uptake in the plant. Excessive nitrogen results in abundant leafy growth where calcium will be directed, rather than to the fruit.