Mulching doesn't just improve the appearance of your vegetable and flower beds, it also improves the growing conditions in the soil. Mulching preserves moisture in the soil, prevents weed seed germination and helps maintain soil temperature. It also helps reduce erosion, and organic mulches aid soil nutrition as they break down. Mulch can be organic--like bark or straw--or inorganic, in materials like plastic or gravel. Use organic mulches for added soil nutrition or for appearance; plastic to keep vegetable fruits clean and off the soil; and gravel for appearance in beds that require minimal watering.
Lay down plastic mulch before planting and after adding any desired soil amendments. Dig a 3-inch-deep trench around the bed, then lay the plastic over the bed with ends in the trench. Fill the dirt back into the trench on top of the plastic, weighing it down.
Place organic and gravel mulches onto beds after planting. Use a 2- to 2.5-inch layer of bark or wood chips or a 1- to 2-inch layer of gravel or rock. Place the mulch under and around the plants.
Remove organic mulches from perennial beds in fall to prevent the spread of disease. Disease organisms settle in the mulch over summer, and may spread in winter to attack plants as they begin to grow again in spring.
Cover perennial beds with a 4-inch layer of straw mulch in winter to preserve soil temperature, which prevents soil heave when the ground goes through cycles of freezing and thawing. Remove the mulch in early spring so soggy soil can begin drying out.
Place a fresh layer of organic mulch around plants in spring once they begin actively growing. Remove any weeds in the bed before mulching, or they will continue to grow up through the mulch.