You Want to Eradicate Moss? Really?

One of the tenets of our approach to lawn care is that “weeds” are messengers sent by Mother Nature to tell us something about the soil below. You can kill the messengers any number of ways — with chemicals, natural products, flaming, boiling water, or pulling them out — but you don’t really change the message when you do so. The weeds will generally keep coming back until you do something about changing the soil. In other words, if your lawn is mostly dandelions and not grass, it’s because your soil conditions favor dandelions.

Moss, to some folks, is the worst weed of all. People call or write all the time about ways to eradicate moss from that six-foot strip of land between their house and the neighbor’s house. My facetious answer is, “Well, you’re going to have to bulldoze your neighbor’s house.”

The general term of moss can refer to any of about 300 or so species of primitive plants that are most commonly found in forests, but they will also adapt to open lawns if the conditions are correct. In some cases, moss forms quite quickly, but in other cases it can take years to colonize. I recall once camping with my mentor, Dr. Richard Churchill, on top of a granite mountain in Western Maine. After a day of hiking, I was more than ready to pitch my tent atop the nice, soft moss carpet — but he wouldn’t let me. “It took at least a thousand years for that moss to form on that rock,” he said. “You wouldn’t want to ruin it in one night, would you?”

A very uncomfortable night on bare stone aside, I’ve learned to love moss even on lawns in the past 15 years. It never needs mowing, watering or fertilizing. The moss-covered area of my property abutting the north side of the house facing the forest never, ever needs attention, except for the occasional branch that blows down. Why on earth would I want grass to grow there that I would only have to mow?

If you do want to be rid of moss, please don’t run out and buy one of those moss-killing compounds. They are generally very environmentally toxic. Instead, take a look at why the moss is growing there in the first place. Here are the probable reasons:

SHADE — In a lawn environment, the most common reason for moss is lack of sunlight. To be rid of the moss, you may have to remove the lower branches of trees — or cut down the tree altogether. When buildings can’t be moved, you may need to learn to live with the moss, or plant another shade-tolerant ground cover.

MOISTURE — Fast-growing mosses are attracted to persistently wet areas. If an area of your landscape cannot be readily dried by the sun or other means, you may resign yourself to the moss.

LACK OF AIR MOVEMENT — I know golf course superintendents who run large fans in shade areas of golf courses so that moss and fungal diseases don’t set in. If you have an area of your property that is shielded from the win, it can be an ideal location for moss to settle in.

ACID SOIL — Moss is almost always an indicator of a low pH, especially if it’s growing in a sunny area. Adding lime or wood ash may be necessary.

LOW FERTILITY — Whenever you see moss growing in sunny areas, the second consideration after pH is general soil fertility. If the soil is just plain dead or lacking organic matter, moss can creep in.

SOIL COMPACTION — Moss doesn’t typically grow on sandy, well-drained soils. It’s almost always found on compacted clay sites, because the clay holds moisture so effectively. Aerating and altering the soil structure can help alleviate moss.