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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

Gardening: Change soil conditions and bid adieu to moss-colonized lawn

Moss can colonize anywhere there is shade, moisture and compacted soil or in this case, gravel. To really get rid of moss, you have to change the soil conditions which can take a lot of work. (Pat Munts / The Spokesman-Review)

Now that the grass is growing, the question of the week seems to be how to get rid of moss in the lawn. The short answer is it’s not easy. The long answer is maybe, after some work. There is no one and done treatment that will get rid of it.

Moss is an ancient plant that developed at least 275 million years ago when plant life lacked vascular systems that could move water and nutrients through the stem, leaves and roots. In other words, it has no mechanism to transport the chemicals we commonly use today. So, we are left with a much more complicated process.

A quick way to temporarily get rid of moss is to apply one of the granular or liquid moss removal products on the market. The active ingredient is iron phosphate which turns the moss black within a day. It can then be raked out of the area. The problem is if you don’t do anything else, it will come back. Guaranteed. To really get rid of moss, you need to change the soil and light environment where it grows. And that involves some serious work.

Moss colonizes damp, shady places and acidic, or low pH levels, and compacted soil. So, the first thing you need to do is remove or thin shrubs and trees that are shading the area to let in more sunlight. Increased sunlight tends to dry out the soil faster which discourages the moss.

Next, once the moss has been removed with moss killer, the soil needs to be heavily aerated. This opens the soil to air and water and reduces the compaction a little bit. To raise the pH of the of the soil, you will then need to apply granular lime and fertilizer. Some of the granules will find their way into the aeration holes and then deeper into the soil.

To restore the lawn in the area, lay down a couple of inches of good quality compost over your aerated ground to create a new seed bed for the grass seed. If shade is still an issue in the area even after your pruning work, select a shade tolerant grass seed to lay down. Most of the shade tolerant mixes contain blends of different types of fescue grass that grow into a nice grayish green lawn. Fescues are also more drought tolerant than Kentucky bluegrass and require less mowing.

Scatter the seed and rake it in lightly. Roll the area with a lawn roller, apply a pelleted mulch and water the area. The mulch expands and helps hold in moisture as the seed sprouts. The new lawn will need to be watered every day for around 20 minutes until the grass is a couple of inches tall. After that it will need watering every two to three days through its first couple of mowings. Apply a balanced fertilizer in mid-June and again in September. Next spring aerate the area again and apply another round of granulated lime with your spring fertilizer.