The Big Sandy Mountaineer -

Mulching is a must for lawn and garden landscapes during the hot summer

The single most serious problem with ornamental plants in Northern Plains region is not a disease, insect or mite problem; it is environmental stress. Stress affects plant material in direct and indirect ways. It can cause damage directly and weaken the plants to the point where they are vulnerable to insect and disease attack. Stress is a problem in the Plains region because we, in our landscaping efforts, are attempting to grow “alien” species (non-native for the most part). If the Great Plains were allowed to revert to their native state, we would find very few woody plant species. The home base for most of the woody plants used in the landscape is forest environments.

Turfgrass growing up to the base of landscaped trees is an unnatural state; in the natural state, these same species are growing in a cool, moist, shaded soil covered by a blanket of decaying leaves and wood. Compare that with the capricious conditions of a typical landscape setting in the Plains: extremes of heat and cold, prolonged dry spells, compacted soil, and turfgrass competition for water and nutrients. Other than planting only the few native species in our landscapes, the stress problem can be alleviated by mulching the trees and shrubs we choose to plant. Here is a list of the benefits of organic mulch:

1. Water conservation – This keeps the water available longer to the root system.

2. Insulation – Mulch protects against temperature extremes, resulting in less injury.

3. A barrier for turfgrass – This has a double benefit of keeping mowers away from the base of trees where injury can occur, and it eliminates the competition from turfgrass roots for water and nutrients.

4. Weed control – Organic mulch at a depth of 4 inches will smother most weeds.

5. Better soil condition – The “organic tea” that results from gradual breakdown of organic matter improves the soil. A number of organic mulches are available. They include wood chips or shredded bark, ground corncobs, soybean straw, leaves, grass clippings and sawdust. Rock mulches create heat islands, do not conserve water and provide an opportunity for mischief. When applying mulch, put it on about 4 to 5 inches thick to allow for settling to 3 to 4 inches. Mulch an area equal to the drip line for maximum benefit to the trees and shrubs. In addition, be sure to keep a mulch-free zone of about 2 to 3 inches around the trunk of the tree to minimize rodent damage in the winter. While mulching will not be a cure-all for our woody plant problems, it can go a long way in relieving many of the stresses they suffer.

This article was written by Ron C. Smith NDSU Extension Horticulturalist (Retired). The complete document is called Horticulture in North Dakota “Seasonal Tidbits and Tips.” The document is available at https://www.ag.ndsu.edu/pubs/plantsci/landscap/h1585.pdf.