Mulching Garden Soil

Friday, August 4, 2017 1:11 PM

Mulching garden soil is not only worth the effort, but for a variety of reasons is probably the most beneficial cultural practice you can engage in to help your plants, vegetables, trees, and shrubs achieve their full potential.

First of all, mulch can greatly decrease the amount of time you need to spend weeding your garden, which all of us would agree is a plus. But, in addition to less time weeding, less weeding means less chance of damaging plant roots through cultivation and weed removal.

Mulch also increases water absorption and reduces evaporation of moisture from the soil. With a good layer of mulch, we don’t need to water as often and the water we use is put to more efficient use. This mulch layer also helps protect our plants from soil-borne diseases by reducing splashing from rain and watering.

Regulation of soil temperature during our hot Oklahoma summers is another valuable reason to add mulch to our gardens. Research has shown that non-mulched garden soil at a depth of 1 inch can vary in temperature by as much as 40 degrees during an average summer day, reaching temperatures of close to 120 degrees. Adding a layer of mulch can reduce that temperature increase by approximately 30 degrees, to a high of about 90 degrees. Reducing these extreme variations in daily soil temperature is beneficial to plant root systems.

Oklahoma soils tend to be low in organic matter, so we recommend organic mulches that can be incorporated into the soil at the close of each gardening season. Examples of organic mulching materials would include bark chips, compost, grass clippings, pine needles, sawdust, and straw. Shredded leaves from the previous season’s yard cleanup also make great mulch, and you can’t beat the price.

Mulches such as sawdust or wood shavings have high carbon to nitrogen ratios that can cause them to leach nitrogen from the soil as they decompose. To compensate for this, nitrogen fertilizers should be increased by about one-fourth.

We generally recommend a mulch layer of between 2-4 inches, but the depth of mulch depends on the texture of the mulch you will be using. For example, if you were to use sawdust, peat moss, or cotton seed hulls, an appropriate mulch depth would be 1” since these are fairly dense mulches. However if you were to use straw, hay, or other more coarse materials, you may need 4 to 8 inches for an appropriate mulch cover.

Mulching your garden may take a little effort, but your efforts will be rewarded with a more beautiful, productive, and healthy garden.