Moss Control in Lawns and Turf

Why do I have moss in my lawn?

Moss growing in lawn areas is a common problem that can have several causes. Keep in mind, however, moss is not likely to invade or crowd out vigorous grasses. Instead, it develops as lawns thin due to poor site or management practices.

Some of the most commons factors that allow moss to develop in a lawn are: Low soil fertility, poor soil drainage, compacted soils, excessive shade, poor air circulation, high humidity, general neglect, irregular mowing, lack of adequate nutrients, and over watering. More often, there are a combination of these conditions that promote moss.

Short term, what can be done about the moss?

Moss can be eliminated if a diligent effort is made before it gets a strangle hold on your lawn. The winter or early spring months (November through early March) are the best time for treatment. 1.) Apply ferrous sulphate or iron sulphate at a rate heavy enough to completely cover or penetrate into the moss. Usually 20 gallons of mixed liquid or 5 lbs of the granular formulation per 1,000 square feet. Make sure the temperature will not exceed 75 degrees after or during treatment or you will burn your grass! Follow with another treatment 4 to 6 weeks later. The iron will also green your lawn without a lot of new growth and reduce most lawn diseases. 2.) Using a commercial lawn aerator (one that will aerate at least 2 inches deep), and while the soil is still wet (allowing proper penetration of the aerator) plug your lawn. You do not have to remove the plugs. They will provide additional soil for seed germination and will dissipate as time goes on. 3.) Reseed your lawn in the spring and apply a small amount of slow release starter fertilizer. Make sure it has less than 10% nitrogen and at least a 25% slow release or you will burn the new seed as it germinates. Rhododendron food is an excellent choice.

KEEP THE IRON ON THE GRASS ONLY! BE EXTREMELY CAREFUL NOT TO ALLOW ANY IRON TREATMENTS TO COME IN CONTACT WITH WOOD, CONCRETE, BRICK, OR ANY OTHER MATERIALS. IT PERMANENTLY STAINS!

A Permanent Solution?

In some cases, you can permanently eliminate moss but it is unlikely. However, you can keep it to tolerable levels by implementing sound cultural practices, by being diligent.

Evaluate the site. Get enough soil samples for a cross representation of your soil structure. A two to three inch deep sample is adequate. Have the samples evaluated by a professional lab. Most extension offices, farm supply stores, or garden centers, will send the samples in for you if properly bagged and marked. So, check with them before taking your samples in for their requirements. There are also kits available to purchase that will give you the basics.

1.) After your sample has been precisely evaluated, apply the recommended rate of lime to raise the ph and lower the acidic level and make all necessary corrections to favor healthy lawn growth. Moss likes a high acidic, shaded, and wet soil and by eliminating these conditions, you will rid your lawn of this menace. For example, prune trees to allow more light to reach the lawn and remove excess vegetation to improve air circulation over the site.

2.) Improve drainage and soil compaction by plugging or aerating at least twice yearly.

3.) Fertilize according to the type of grass growing on site and type of site. Lawns in full sun require more fertilizer than those in shade. Avoid excessive watering and mowing too short. Mow between two and three inches, preferably at the high end of the range for summer.

4.) Use iron in your granular fertilizer program every time you feed your lawn. Usually 5% is adequate.

5.) Check for reinfestation during the winter months and apply iron, if needed.

KEEP THE IRON ON THE GRASS ONLY! BE EXTREMELY CAREFUL NOT TO ALLOW ANY IRON TREATMENTS TO COME IN CONTACT WITH WOOD, CONCRETE, BRICK, OR ANY OTHER MATERIALS. IT PERMANENTLY STAINS!

Finally, make sure the proper grass is growing for the site conditions present. For example, Kentucky bluegrass is ideal for full-sun areas but does not typically do well in shade, thus tends to thin out and allow moss to invade. Fine fescue, such as red fescue, is a better option for shade.

Meanwhile, back at the farm...