Mulch reduces evaporation from the soil surface, moderates
soil temperature, and insulates roots from summer heat (and winter cold). Mulch
suppresses weeds, reduces soil compaction, prevents erosion, and adds organic
matter to the soil.
Mulch is any material that protects the soil surface and
allows air and water through. Organic mulches--mulches derived from plant
materials--not only protect the soil but add nutrients over time while enriching
overall soil composition.
Summer mulch. Apply three to four inches of
dried leaves or compost or grass clippings or straw around plants at midsummer
to protect plants from hot weather and reduce the soil temperature by 10°F or
more. Soil temperatures of greater than 85°F can slow plant growth. The
temperature of soil under mulch changes much more slowly.
Mulch protects bare soil from
being compacted over time by the drying of soil particles in the sun and the
beating of rain or irrigation. A thin layer of mulch will protect soil microorganisms and other
beneficial soil borne organisms from cooking in the summer heat.
Almost all plants benefit from
the protection of mulch. Vegetables
that most benefit from summer mulching are eggplants, tomatoes, cauliflower,
celery, potatoes, currants, and gooseberries. These crops especially appreciate
cool, loose, well-drained soil.
Applying mulch. Two cubic feet of compost mulch
can cover an area of 8 square feet to 3 inches deep; one cubic yard of compost mulch
covers an area of 108 square feet to 3 inches deep.
Mulch should be applied loosely and not compacted. Mulch
should be kept back a few inches from the stems or crowns of plants and trunks
of trees. If placed too closely, mulch can retain moisture and cause plant
stems and trunks to rot.
Almost all plants benefit from the protection of mulch. Vegetables that most benefit from summer mulching are eggplants, tomatoes, cauliflower, celery, potatoes, currants, and gooseberries. These crops especially appreciate cool, loose, well-drained soil.