Q.: Mulching seems to be extremely popular with gardeners. Is it really important? If so, how should I use it for the best results?
A.: Mulching is very important. Mulches work like a blanket over the top of the soil to retain moisture and keep the roots of the plants cooler in the summer and warmer in the winter. They inhibit weeds; prevent diseases in the soil from splashing onto the plants during rains or watering; and improve the appearance of the garden.
When planning your landscape don’t be stingy with the mulched areas. Use loose, free-flowing curves for appearance and to make mowing easier. Define the edges crisply with a boundary, such as edging, for an attractive finish, to help hold the mulch in place and prevent lawn grasses from creeping into the bed.
Your trees can be a big help in designing beds. Include at least half of a large tree’s drip-line into the bed and all of the drip-line of small trees. If you are naturalizing shady areas, the general rule is to mulch all areas that are shaded 50 percent or more of the time.
Remove all weeds in the area before spreading mulch, then apply 3 to 4 inches of mulch over the entire area to prevent them from growing back. Just applying the mulch on top of the weeds will not kill them. There are safe herbicides available for use by homeowners, if necessary. The mulch should be applied 1 to 2 inches from the stems of plants to reduce rotting of the stems and keep mice and voles from using it for cover and chewing on the trunks and stems.
Good mulch should be attractive, allow water to penetrate, retard evaporation, inhibit weeds, be affordable, be durable, be nontoxic to plants and animals, not attract unwanted insects, and control erosion.
There are two basic types of mulch: organic and inorganic.
Organic mulches come from nature, break down or decompose over a period of time and become part of the soil, so they must be replaced periodically. They encourage worms and beneficial soil organisms that improve soil quality as they decompose. There are many types of organic mulch available in your yard without any additional cost. Grass clippings are good as long as no herbicide has been added to the grass to kill broadleaf weeds. Herbicide free garden waste, leaves and small prunings should be shredded and or composted before use.
Newspaper is good. It needs be 4 to 5 sheets thick and shredded paper 1 to 1.5 inches thick. Both benefit from an inch or so of mulch, such as pine straw, on top to keep them from blowing away.
Straw and hay are cheap, but decompose rapidly, so need they to be replenished fairly often. They are also not as attractive as some other mulches and may contain seeds that will sprout in the garden.
Composts, manures and soil conditioners are especially good for the soil, but decomposed quickly and have to be replenished often.
Wood chips, wood shavings and sawdust contain bark and small pieces of wood; are attractive and provide good weed control, but may attract insects.
Pine and cypress bark, and pine needles are especially good for acid-loving plants.
Inorganic mulches decompose slowly or not at all so they do not have to be replenished as often. They control weeds well, but be sure the one you use allows water, nutrients and sufficient air flow to the plants.
Rocks and gravel are fairly cheap, keep weeds down and do not wash during a rain. However, they are heavy to move and will sink into the soil.
Black plastic is not recommended. It controls weeds, but does not allow water and nutrients to penetrate.
Landscape cloth can be cut to fit your needs. It allows water, nutrients and air flow, and is effective with most weeds. It is not attractive, so needs to have another mulch placed on top and usually needs to be anchored to keep it in place. Soil will accumulate on it after a while, allowing weeds to grow on top of it.
Rubber mulch will not fade, compact or decompose for up to 10 years. It is often used on playgrounds. It does not attract insects or float during heavy rain, and it inhibits molds. Some products have a strong odor and the fact that it does not decompose can be a disadvantage as well as an advantage.
Call the Carroll County Office of The UGA Extension Service, 770-836-8546 for additional information on mulching.