April 26, 2009 in Idaho Voices

Moss lends grass wrong kind of green

Pat Munts
 

Yes! The lawn is finally turning green. Winter is over and the grass is coming up. Wait a minute. That’s funny looking grass. Rats, it’s moss. Even our wild winter couldn’t slow it down.

So why is it so persistent?

First, moss has been around for millions of years and survived everything nature has thrown its way including numerous extinction events and cycles of climate change. Its simple biology has allowed it to adapt to living in wet and dry environments from the Arctic to the tropics and even on the edge of hot springs and at the bottom of lakes. Your lawn is a little piece of paradise for it.

Second, moss has several methods of reproduction. It sends out spores (think seeds, only simpler) that easily travel to new locations; it sends out shoots in the spring from parent plants and finally by fragments that break off the main plant and find their way to new locations.

Because it is so adaptable, it will grow in areas where other plants like your lawn struggle, eventually crowding out the grass completely. Therefore moss in lawns or growing beds is usually indicative of poor growing conditions such as low soil fertility, high soil acidity, heavy shade, improper watering practices, diseased grass and poorly drained or compacted soil.

There is no quick fix to remove moss. Several types of moss killers are available on the market that will kill existing patches of the stuff for a short period. Moss killers, especially the iron phosphate-based ones, need to be applied carefully so they don’t stain walks, siding and clothes. Raking moss out will remove the top of the plants but will leave enough fragments that it will grow back quickly.

The long-term fix involves changing the environment so the plants you want will grow properly. Start by checking your watering practices. Moss thrives in damp places other plants like grass don’t like. Check your sprinkler system and adjust timer settings or spray patterns to reduce overwatering and ponding. Reroute downspouts and other sources of runoff to reduce ponding.

The next thing to look at is the condition of the soil. Compacted, poorly fertilized areas don’t allow air and nutrients to reach the root zones. Aerate mossy areas in the spring and fall to help break up compacted soil surface layers. Add an inch or two of good quality compost for several years to the area to improve fertility and provide new soil for the grass to grow in.

Remove overhanging branches and shrubs to let in more light. Kentucky bluegrass does not do well in shade and will thin out, giving moss an opening to move in. If the area is still too shady, try planting a tall fescue grass seed that is much more tolerant of shade.

Lastly, consider letting the moss become an element in your landscape. Japanese and Chinese garden designers have made an art out of incorporating it into landscape. A walk through the Japanese Garden at Manito Park will demonstrate its versatility and simple beauty.

Pat Munts is a Master Gardener who has gardened the same acre in Spokane Valley for 30 years. She can be reached by e-mail at pat@inlandnwgardening.com


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