Does Hydrated Lime Kill Moss?

Hydrated Lime

• Most people use hydrated lime because it works quickly, significantly raising soil pH over a short period of time. Hydrated lime is a dangerous, caustic substance. It is not only hazardous to humans -- who should always use gloves when applying it -- it is hazardous to plant foliage as well. Because hydrated lime can burn plants, you want to keep it away from your lawn: Although it does kill moss, it can just as easily harm turfgrass. Using it as an herbicide on other plants is equally ill-advised.

Controlling Moss

• In addition to the danger that hydrated lime will harm your turfgrass, killing moss in the lawn is not the answer. Even if you use a moss killer that is specifically formulated to be gentle on grass, the problem will remain. Moss is opportunistic, and grows in bare or unhealthy patches of the lawn because grass cannot compete with it. Destroying moss will not stop it from coming back in a particular patch of soil if there is still no lawn growing there. The best bet, therefore, is to improve the health of your lawn.

Determining Lime Needs

• If your lawn is straggly and has bare patches, this is a good indication that you may have a pH imbalance. The first step toward a healthy lawn is to determining whether or not it is growing in the proper soil pH. Each grass species has its own ideal range, so figure out what your target pH is, test the soil and determine whether or not the two are matching up. Moss tends to appear more readily in acidic soils than in neutral or alkaline ones, so addressing soil pH can help take care of this problem.

Applying Lime

• The application rate of lime depends on many factors, including your starting soil pH, ideal pH and the consistency of your soil. Sandy soils require less lime than loamy ones, which require less than clay soils. The amount required will therefore vary according to the combination of these factors. For instance, raising clay soil from a pH of 5.5 to 6.0 requires 35 pounds per 1,000 square feet. If you want to avoid burning your lawn, you should avoid harsh substances like hydrated lime or burned lime in favor of gentler agricultural lime.