How Much Lime Do Tomatoes Need?

Tomato pH Range

• Tomatoes need a pH range between 6.0 and 7.0. To test your existing soil's pH, use a home testing kit from a gardening center. Dig a 6-inch hole in the proposed planting area. Collect soil from the bottom of the hole. Make sure that you take out debris and other vegetation. Follow the directions according to the pH testing kit. Alternatively, take a soil sample to your county extension service for a comprehensive analysis. A pH range below 6.0 means the soil needs to be limed.

How Much Lime

• Spread 5 lbs. of lime per 100 square feet for soil pH ranges between 5.6 and 6.0. Apply 10 lbs. of lime per 100 square feet for pH ranges between 5.0 and 5.5. Break up the application in half to apply 5 lbs. in the spring and the other half in the fall. Soils that have a pH below 4.9 should be limed with 20 lbs. of limestone made in four applications throughout the year.

How to Apply

• Apply dolomite limestone when the ground isn't frozen. If applying lime to a new garden, work the limestone into the first 6 inches of topsoil. For existing tomato crops, lime may be applied around the plants and watered in. You can also spread limestone right before a rain. Refrain from applying limestone during the heat of summer, because it can burn up your tomato plants. Also, avoid liming water-stressed plants.

Problems

• Yellowing tomato plants indicate that your garden soil needs either lime or sulfur. Soil pH ranges that are outside of the tomato plant's preferred range prevent the plant from absorbing important nutrients such as iron. The result is a condition called chlorosis. Chlorosis occurs when the plant cannot absorb enough nutrients to produce chlorophyll. Gardeners may also see an overall decline in health or a reduced yield from their tomatoes. Testing the pH early prior to planting and liming the soil or adding sulfur to alkaline soil prevents chlorosis.