Mulch reduces weeds and improve soil

The underlying principle for mulching is “the best way to improve any soil is to add organic matter”. No matter how good or how poor your soil is, organic matter will always improve it. Organic matter adds water and nutrient holding capacity to sandy soil.  It opens up clay soils so they accept and drain water more rapidly.

Earth worms and soil micro-organisms use organic matter for food. As they break it down into humus it adds nutrients for the plants. The micro-flora in the soil develop a symbiotic relationship with plant roots so that the plants make better use of the resources in the soil and grow more vigorously.

Organic matter on top of the soil reduces water evaporation so that it dries out more slowly. It keeps soil from compacting so that water flows in more quickly. It shades the soil and keeps it cooler. It blocks light from reaching weed seeds on top of the soil. Removing light reduces weed seed germination by up to 90%. Hence, mulch is one of the best forms of natural weed preventer.

Bark Dust

The organic matter which we have available that is inexpensive, uniform, high quality, and without weeds or pests is bark dust. Bark dust is simply bark from trees which has be ground into smaller particles from ¼ inch to dust. Larger granules of bark can also be used including bark nuggets.

One to three inches of bark dust can be added to the soil of a flower bed and incorporated into the soil with a shovel or small tiller before planting. If an inch or more of bark dust covers the soil from last year, it can simply be mixed with the soil underneath with a hand trowel or hoe as plants are transplanted.

One inch of bark dust added after transplanting helps water infiltration, reduces weed growth and gives an attractive, finished look.


Allen Wilson

Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.

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