Lime is soil input that most North Carolina gardeners will use at some point. Many see an increase in plant growth and productivity as a result of applying lime. This article will inform gardeners on the most effective and economical liming material, and the best practices for application.

Most native Piedmont soil is highly-weathered, acidic clay. In these soils, essential plant nutrients are tied up with soil particles. Lime neutralizes excess soil acidity,

The soil pH is used to determine the lime recommendation on soil test report.

“unlocking” nutrients and making them available for plant uptake. It also raises soil pH into the optimum (6.0-7.0) range for most plants, blueberries excluded. Proper liming enhances nutrient availability, promotes plant and root health, and supplies the calcium (Ca) and magnesium (Mg) to plants.

Unlike synthetic fertilizers, limestone is a mined material and can be used in organic farming and gardening. Most lime sold in North Carolina comes from quarries in Tennessee and Virginia. The quality and purity of lime products is regulated by state law, and companies must adhere to strict labelling.

Two lime materials, calcitic and dolomitic lime, are used in agriculture. Both contain Ca and are equally effective at raising pH. Dolomitic lime also supplies Mg, is often cheaper, and is more widely available in our area. It is recommended for sandy soils and when a soil test shows Mg is deficient. Calcitic lime may be used if you have issues with blossom end-rot, a common problem of tomatoes and peppers caused by Ca deficiency. Piedmont soils tend to have high Mg, which crowds out Ca for root uptake and may lead to this disorder.

Not all liming products are created equal. They vary in their ability and how quickly they neutralize soil acidity. A finer ground lime breaks down and reacts with soil more quickly. For home gardeners, the choice is based on ease of handling and spreading. Most farm supply stores will have ground, granular, and liquid lime to choose from.

Aglime spread on a cornfield. Photo courtesy of Arcadia Limestone Co.

Ground lime, also called aglime, is the cheapest and used in production farming. Its drawback is that it is dusty and hard to spread. Pelletized or granular lime is ground lime in a pelleted form. This form is recommended for lawns and gardens because it is easy to spread and get even coverage. Liquid lime consists of ground lime suspended in water. It is the most costly, easy to use, and fast acting. But it tends to have a short-lived effect and must be re-applied every year.

Liming materials: pelletized calcitic (left) and dolomitic (right) lime

Other types of lime you may find for sale are hydrated and quick lime. These are not recommended for lawns and gardens. Frequent application of wood ashes can raise soil pH. Keep in mind that to be effective large amounts of ash are needed, about triple the recommended lime rate.

Fall is an excellent time to test your soil and apply lime. It takes time for lime to change soil pH so apply well in advance of planting time, a minimum of 3 months before planting time. For fastest results, till or incorporate by hand to the rooting depth and water in after applying.

Have your soil tested to determine how much lime to apply. Soil pH is sometimes too low and sometimes it is too high. It is important to get a soil test and not assume you need lime. The soil report will give a recommended lime rate for what you are growing. Soil test kits are available at the N.C. Cooperative Extension of Yadkin County office, 2051 Agricultural Way, Ste 201 Yadkinville NC by calling 336-849-7908. Soil testing is FREE from April 1 to December 1. Take advantage of the opportunity this fall!