Is Lime Good for Tomatoes?

What Is Lime?

• Lime is made from crushed limestone, sometimes mixed with other chemicals to enhance its benefits as a soil amendment. Lime in the form of calcium carbonate is a safe and effective product for changing soil pH levels. Dolomitic or dolomite lime is another form that is higher in magnesium than standard lime. Hydrated lime (calcium hydroxide), commonly known as "builders lime," can also be used. Quicklime (calcium oxide) is not recommended for garden use.

What Does Lime Do for Tomatoes?

• Tomatoes grow best in soil with a pH range of 6.5 to 7.5. Use lime to raise the pH of your soil if it is too acidic. Maintaining the proper acidity level makes nutrients such as nitrogen, phosphorus and potassium more available to the plants. Lime also provides the trace minerals of calcium and magnesium; both are important for plant growth. Calcium deficiency causes blossom end rot disease in tomatoes and magnesium deficiency appears as chlorosis, or yellowing of the leaves between veins.

Do I Need to Add Lime?

• Conduct a soil test to know if you should add lime. Buy a soil test kit from a garden supplier, or your state university may have an agricultural extension department that offers a soil testing service. You want to determine the pH level of your garden soil, as well as the current levels of nitrogen, phosphorus and potassium. Use fertilizer as needed to improve nutrient levels and add lime to adjust soil acidity to the optimum level.

When and How Do I Apply Lime?

• Ideally, lime should be worked into cultivated soil to a depth of at least 6 inches before planting. If plants are already established, lime can be scratched into the soil surface and watered in. Apply lime according to the packaging directions or at a rate of approximately 1/2 lb. per square yard of soil. You should not apply lime and manure at the same time because the combination creates ammonia, which can damage your plants.