Moss Control in Grass

Shady lawn

While moss can be an attractive feature in a rock garden or along a stream bed, moss has no place in a healthy lawn. When moss appears in your lawn, removing it is a tough job and only a partial solution to the problem.

Start With the Moss

While it will not be a permanent solution, it is still important to remove moss once it appears. A number of commercial products containing ferrous sulfate will kill moss, but physically clearing it away makes it easier to treat the underlying soil conditions that caused it to grow in the first place.

Scout Out the Causes

Manual lawn aerator

Moss thrives in poorly drained, well-shaded, highly compacted and acidic soils. Have your soil tested for pH levels or purchase an inexpensive test kit. Use a garden spade to determine how tightly compacted the soil is. Inspect the tree canopy and watch the mossy area throughout the day to see how much sun is getting through.

Amend the Soil

If your soil is too acidic, treat it with lime according to the directions on your soil test kit. Tightly compacted soils should be tilled and amended with organic materials like peat moss and compost for better drainage. At a minimum, areas around the treated soil on the edge of the moss infestation should be aerated.

Get Rid of Standing Water

If soil amendment is not enough, consider installing a French drain to carry away standing water. This is essentially a sloping trench filled with gravel and sometimes perforated PVC pipe which helps carry excess water to a lower area like a nearby catch basin.

Here Comes the Sun

Dappled lawn

Look for branches in the tree and shrub canopy that can be pruned safely, allowing more sun to reach the mossy area. Sunlight is the enemy of moss. Plant the area with a shade-tolerant grass seed mixture and remember not to over-water.

References

• Oregon State University: Physical Moss Control for Lawns
• Washington State University: Moss Control in Lawns