Apply mulch to help plants through hot, dry spells

By Nancy Rose

University of Minnesota Extension

Applying mulch is one of the best things you can do to help your plants through hot, dry spells this summer.

Bare soil heats up rapidly on hot, sunny days and allows soil moisture to evaporate. As little as an inch or two of mulch spread over bare soil can significantly reduce soil temperature and reduce water loss.

This reduces plant stress on hot days and conserves valuable water resources.

Many types of mulch can be used in home landscapes. Organic mulches include materials such as wood chips, bark nuggets, pine needles, shredded leaves, straw, grass clippings and compost.

Organic mulches break down over time, gradually adding nutrients and improving soil structure. Inorganic mulches include pea gravel, crushed rock and landscape fabrics. These will help hold soil moisture but are often more difficult to apply or remove and do not add to the soil.

Any kind of mulch will help plants survive hot, dry conditions. However, some mulches work best in certain landscape situations. Coarse mulches that decompose slowly are ideal for landscaped areas that are rarely disturbed with digging.

Mulches that break down more quickly are best for planting areas like vegetable and annual gardens where the soil is worked up annually. Here are some specific recommendations:

• Trees and shrubs (individual or group plantings) - Apply two to four inches of coarse, long-lasting mulches like wood chips or bark nuggets.

• Perennial flower beds - Apply two to three inches of finer mulch such as shredded leaves, pine needles or cocoa bean hulls. Coarser mulch can be used around perennials that are rarely dug and divided.

• Annual flower beds - Apply one to two inches of attractive, fine-textured mulch such as cocoa bean hulls or finished compost.

• Vegetable gardens - Apply two to six inches of fast-decomposing mulch such as straw, hay, grass clippings or partially decomposed compost or shredded leaves.

Many types of bagged or baled mulches are available at nurseries, garden centers and home improvement stores. Also check with your municipality - many offer mulch and compost products to local residents.
For more detailed information on mulching trees, shrubs, flower beds and vegetable gardens, visit www.extension.umn.edu and search on "mulching landscape" for an article titled "Mulching the Home Landscape."

Nancy Rose is a horticulture educator with University of Minnesota Extension.