Welcome to Mulch 101. Today we are going to go over some of the benefits of using mulch and list some of the commonly used organic mulches. Organic mulches are derived from living plants. Mulches are applied to the soil surface and help conserve moisture, moderate the soil temperature and suppress weeds. Mulches not only create a better environment for plants, they also beautify the yard and garden and make maintenance easier. When used around trees and planting beds, they can eliminate the dreaded summer diseases – mower blight and weed-eater syndrome.
Organic mulches are applied to the surface of the soil and will break down through time. If these organic materials are tilled into the soil, they serve as soil amendments. Soil amendments are materials that are incorporated or tilled into the soil in order to improve the soil texture, water retention and aeration. If tilled into the soil, materials like sawdust tie up nitrogen that would otherwise be available to plants.
There are several organic mulch materials that are suitable for annual vegetable and flower gardens since they break down in one season. These materials include compost, hay and straw (as weed seed free as possible), lawn clippings and peat moss. If you are mulching a vegetable or cut flower garden, putting down several sheets of black and white newspaper and wetting them before putting additional mulch on top will further suppress weeds.
Organic mulches that last longer than a season are generally used for perennial beds, trees and shrubs. These include shredded bark and bark chips or chunks, pine needles, and sawdust. In general, the larger the particle size the longer the mulch will last. For example – bark chunks will last longer than shredded bark, but shredded bark will break down more quickly to add organic matter to the soil. Even with the more slowly decomposing organic mulches, you will need to replenish the mulch through time.
Most organic mulches should be applied from 2-4 inches deep on annual and perennial plants as well as trees and shrubs. Keep in mind that you should not mulch over the crowns (where the roots meet the top of the plant) of perennial flowers. Taper the mulch down to the crown of the plant and do not cover it. Trees benefit from mulch application in a ring around the base – but remember to avoid having the mulch touch the base of the tree – especially over winter when it can serve as cover for critters that may harm a newly planted or thin bark tree.
Oh, I almost forgot your homework! Recommended reading for Mulch 101 is the University of Missouri Extension publication “Mulches” by Dr. Chris Starbuck at http://extension.missouri.edu/explorepdf/agguides/hort/g06960.pdf
Direct comments or questions concerning this column to Marilyn Odneal via email at MarilynOdneal@missouristate.edu.
