Wood-based mulches cut off oxygen to the plant roots, can harbor or even introduce disease to the flowerbed, and prevent water from draining deeply into the soil. My flowerbeds are topdressed with 4-inches of homemade compost made from yard waste which has been aged for two years.   The image above shows compost being used around newly installed plants in early summer. By late summer, the plants had spread and very soil was left bare. The following growing season practically no soil was showing. Compost returns organic matter to the soil in a usable form. Organic matter in the soil improves plant growth by stimulating the growth of beneficial microorganisms. The practice of sterilizing the soil by covering it with black plastic to bake in the sun, not only kills weed seeds, it kills all those beneficial microorganisms and the gardener's best friends, the worms. Compost also loosens the soil to allow better root penetration, improves the capacity to hold water and nutrients particularly in sandy soils, and adds essential nutrients to any soil. Improving your soil is the first step toward improving plant health. The balance of this article is not included in the demonstration.