Mulching is popular finishing touch to landscapes because of the finished, manicured appearance it provides as well as the plant health and weed control benefits it offers. Shredded hardwood mulch, pine needles, and mini-nuggets are all popular and pretty much equally effective. The mulch for you largely depends upon personal taste—whatever looks best to you and works well in your landscape and budget is the type you should choose. (Find benefits and drawbacks of different mulches here.)
Benefits of Mulching
In addition to providing that “finished landscape" look, mulches provide many benefits to plant growth and reduce the demand for landscape maintenance. Mulches help to conserve soil moisture by reducing evaporation—thus reducing the need for irrigation and watering. They also modify soil temperatures in our extreme seasons of hot and cold—lowering soil temperatures in summer, favoring root growth and insulating soils in winter, protecting roots from cold damage.
A good layer of mulch is also very effective in preventing weed growth, limiting the germination of weed seeds and inhibiting their growth. When organic mulches decompose, they provide nutrients and add humus to the soil, both improving soil texture and promoting more vigorous plant growth.
Mulch also helps to protect tender root systems, cushioning the effects of heavy rains and foot or vehicular traffic, which can cause excessive compaction of both soils and roots. In addition, mulching rings around trees and mulched planting beds naturally prevent physical injuries to landscape plants caused by lawnmowers and mechanical trimmers—injuries which often contribute to the early decline or death of even established plantings.
How to Mulch
Most mulch should be applied to a depth of two to three inches and maintained at a depth of less than four inches. Annual top dressings may be necessary to maintain that "freshly-finished” look, however, keep in mind that the less you add to an established area the better.
When mulching around the base of plants, do not mulch up against the trunks of trees or shrubs. Start mulching just beyond the trunk and gradually taper up to the two to three inches as you get away from the plants. This will prevent excess moisture around the base of the plants which can lead to suffocation and rotting of the roots.
Avoid using freshly ground sawdust, tree-chippings and any other organic matter that has not been aged or composted. In the process of decomposition these materials will take oxygen and nutrients from the soil and can literally starve nearby plants to death.
When mulching with needles you can achieve a clean, professional look by tucking the edges under with a spade. This looks best if the beds have been edged with a “V” cut.
When to Apply
Mulch can be applied at any time of the year, but the most effective times are early spring (before the leaves open) and in the late fall after we have had several frosts. Avoid mulching in late summer/early fall because mulching at this time can keep soil temperatures too high for plants to harden off.