Q. What is the biggest improvement I can make to my garden that will reduce watering needs and control my weeds?

A. This is probably the #1 question that every gardener has asked. The biggest improvement to any garden is mulch. Depending on materials used, mulches have many benefits, including:

• Reduces evaporation from soil surface, cutting water use by 25-50%
• Organic mulches promote soil microorganism activity, which in turn, improve soil tilth and helps reduce soil compaction
• Controls weeds, which rob soil moisture
• Stabilizes soil moisture
• Prevents soil compaction
• Moderates soil temperature extremes
• Controls erosion
• Gives a finished look to the garden, improving aesthetic quality

There are two types of mulches—organic and inorganic. Organic mulches include wood and bark chips, straw, grass clippings and seed hulls. Inorganic (or inert mulches) include weed-barrier fabrics, gravel and rock. The selection of mulch depends on the intended use. If soil improvement is the major goal, consider using organic mulch that gradually breaks down. If the area is used primarily for annual flowers, it is often more practical to use a temporary organic mulch that can be turned under each fall. Apply most organic mulches to a depth of three to four inches and keep them at least six inches from the base of plants.

Weeds can be a problem in Colorado gardens. Weeds are brought into gardens in manure and soil amendments we use, sometimes by deliberate introduction by gardeners and also by neighboring plants and weeds. Did you know that one dandelion plant produces 15,000 seeds? Weed seeds can be buried in our soils and are viable for many years! The best weed control is persistence, vigilance and mulch.

Sometimes black plastic is used by homeowners or landscape designers. The plastic is usually covered with rock. Black plastic is very undesirable for planting areas and is not recommended. The plastic reduces air infiltration into the soil, creates soil moisture problems and increases soil temperatures, which can injure or kill tender plant roots. The soil is often very dry or very wet under plastic.

For more information on mulch, read Colorado State University Cooperative Extension Fact Sheet #7.214 -“Mulches for Home Grounds” or contact your local Cooperative Extension Office.

Gardening and Insect Fact Sheets are available on-line by clicking HERE.

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This page updated:  April 24, 2007