While most seasoned gardeners understand how mulch around plants helps them thrive, they may not be as certain about choosing a particular type of mulching material. Shredded hardwoods provide benefits that non-organic mulches like rubber or rocks don't bring to the party.
Benefits and Considerations
Like any type of mulch, shredded hardwood helps stop weeds from growing up around the plants and keeps moisture in the soil, where it is available to the plants, as well as regulating the temperature of the soil. Unlike some other kinds of mulch, however, wood shreds also slowly fertilize the soil as they decompose over time; they last longer than other wood mulches and stay in place through heavy rains or watering. Because shredded hardwood is smaller than bark pieces or other types of materials, you can spread them with less risk of damaging small, tender plants. It is important to note that the fertilizer benefit is not immediate and that the decomposition process may deplete the soil of nitrogen, especially if it is turned into the soil. Using a soil test and amending the bed with a nitrogen-rich fertilizer, if the results indicate a need, will remedy that problem.
Before Laying the Mulch
Preparation for mulching your beds and garden starts even before you place the plants. The bed should be cleared or treated with an herbicide before you put down the wood shreds. One option is to pull any existing weeds by hand, working to get the entire plants, roots and all. As an alternative, use a pre-mixed glyphosate herbicide to kill the weeds. For the best results, spray until the weeds are thoroughly drenched but not dripping, on a day when there is no wind to blow the herbicide onto other plants. Read the label carefully, wear protective clothing and use recommended safety equipment. Additionally, if you are pregnant or nursing, you may want to let someone else spray the glyphosate; wear gloves when gardening to prevent illnesses from pathogens in the soil as well. You'll get more benefit from the organic mulch if you don’t use landscaping fabric, as the nutrients from the breakdown of the wood can get into the soil better if it is in direct contact with the ground.
Laying the Mulch
The best time to mulch depends on your purposes for mulching. To protect perennials from winter frost and freeze damage, wait for the ground to cool slightly in the fall and then cover the ground around the plants before the first freeze. To keep the soil cool and moist in the summer, lay the mulch mid- to late spring after the ground has warmed to optimal growing temperature. Apply the mulch to an even depth, usually between 3 and 4 inches, but not more than 6 inches. For a 10-by-10-foot plot, you need about 25 cubic feet of shredded wood mulch.
Maintaining the Mulch
One common mistake new gardeners make is placing the mulch all the way up to the base of the plants, which can cause rot in the roots or stem, as well as bringing pests closer to the plant. Leave a 1- to 2-inch circle around each plant to avoid those problems. For the best results, don't pile fresh mulch on last year's layer. Before you plant new flowers or shrubs, turn the old mulch into the top few inches of the soil. If that isn't practical for your bed or garden, fluff the old material before adding a light layer of fresh wood to the top.