A properly spread mulch layer is a thing of beauty.
Well, at least it's a useful tool in the yard and garden.
Mulch is a layer of material that is placed over the soil surface. A wide range of materials can be used as mulch. For the most part, your plants don't care what type of mulch material you use; your decision should be based on your aesthetic requirements and your finances.
I prefer organic mulches, such as grass clippings, wood chips or bark. They look more natural, and as they decay, they add organic matter to the soil.
Inorganic mulches, including rocks, gravel and rubber chips, have the benefit of lasting practically forever. They don't rot, so usually don't need to be replaced.
One of the major benefits of mulch is that it keeps the soil temperature constant. In the summer, soil under a mulch layer is much cooler than bare soil; in the winter, mulch prevents dangerous fluctuations of freezing and thawing.
Mulch reduces soil moisture loss, which is vitally important at this time of year.
Finally, mulch can prevent weed seeds in the soil from germinating.
On the down side, most mulches do nothing to prevent weed seeds that blow into the garden from germinating. Even with mulch, a garden bed can become a weedy mess after a few years. There are some mulch products available that have been pretreated with a pre-emergent herbicide which prevents this, but be super careful when using them! They can damage sensitive plants.
Mulch layers should be between 2 and 4 inches deep. Any less than 2 inches, and you don't get the weed control, cooling or soil moisture retention benefits.
To prevent wood decay and root rot, never pile mulch against the trunk of a tree. Always pull the mulch a few inches from the trunk.
For more information on using mulch or other garden products, contact the Purdue Extension Service at (812) 435-5287.
Larry Caplan is an extension educator-horticulture with the Purdue University Cooperative Extension Service, Vanderburgh County/Southwest Indiana. You can send e-mail to him at LCaplan@purdue.edu.
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