We need trees for many reasons. Trees reduce air pollution, filtering the air we breathe. The leaves absorb ozone, carbon monoxide and sulfur dioxide and release precious oxygen. Trees reduce the threat of flooding by intercepting stormwater runoff. Trees provide homes for wildlife, and treehouses for us, of course. The benefits of trees — economically, environmentally and socially — are overwhelming.

The benefit we probably think of first, though, is shade. Strategically placed trees can cut down on cooling bills in the summer, and I don’t know many people who want to have a picnic out in a hot, open area.

This time of year, many phone calls come in pertaining to lawns, a lot of which have to do with moss overtaking the lawn. Moss is not actually taking over the lawn, of course, it just happens to grow in conditions unfavorable for the growth of grasses — nature plants a ground cover where lawns do not grow well.

What is moss?

Mosses are small, green, primitive plants with reduced leaves and a mass of fine, threadlike stems. They form a low, green mat atop the soil, which makes an excellent ground cover. Mosses do not steal nutrients and water from lawn grasses as they produce their own food and can absorb nutrients directly from the air when the humidity is right.

I love the almost lime green color of some of our mosses. Many homeowners may gasp at the thought of moss growing in their landscape, but it is quite beautiful and has been a part of Japanese gardens for years. It is also a good bioindicator of air and water quality.

Where do mosses grow?

More than 400 species of moss (liverworts and algae, too) grow in the Southeastern United States. As you can imagine with so many species, moss grows in a variety of places, some even in full sun. But for the most part, moss thrives in Alabama’s shady areas. We see it often in our forested areas.

Seeing as how moss will grow on the side of a brick, compacted soils are no problem — remember the nutrients are coming from the humid air, not the ground. Perhaps your yard does not drain well and a good rain leaves behind soggy areas, which shade exacerbates. No worries — moss will grow there too. Maybe your yard is “au natural,” with no fertilizer or lime — moss doesn’t mind. Now ask yourself: What do shade, soggy soil, low fertility and compaction have in common? These are all places lawn grasses do not grow well, usually in the shadow of trees.

What can I do about it?

Unfortunately, there is not a magic cure. Sure, you could spray it with something that would work temporarily, but the moss will return and the grass still won’t grow there. To actually rid yourself of moss, you must modify the environment.

You have a choice to make: To allow in enough light for grass to grow properly, it is usually necessary to open up tree canopies or drastically thin or remove trees so the grass receives more sun. I always pick shade — the heat of July and August make up my mind for me. Besides, shade may not be the only factor. Fertility, soil pH, soil compaction and water drainage all need to be addressed if moss is not in your landscape plans.

How do I grow it?

Nature does a good job of planting moss. It really is an excellent, low to no maintenance ground cover in gardens and around shady areas. If you already have moss growing, great. Hand remove, or chemically remove, any surrounding grasses and weeds. Scratch the surface lightly — the moss will spread faster.

You can relocate a few clumps here and there, “planting” it in areas devoid of other plants. Keep relocated moss watered, although nature will usually do this for you, and harvest it from areas similar in environmental conditions to where you are transplanting. For instance, you will have better success transplanting moss growing under one tree to a nearby area under another tree rather than moss growing on a piece of wood or stone statue.

Speaking of which, there is a way to speed up the process of growing moss on stone statues or brick paths as well. It may take a month or more before moss starts to establish. Try a simple recipe of 2 parts moss (off your own property), 2 parts water and 1 part buttermilk. Blend well and spread over the area you are trying to cover. Remember to sprinkle or mist often — you don’t want it to dry out.

For help on other home and garden questions, call the Master Gardener Horticulture Helpline at 1-877-ALA-GROW (1-877-252-4769) or visit us online at aces.edu.