Mulching: important, efficient, cost effective

The temperatures are heating up and even though we have had moisture, there will always be a need to conserve moisture and keep plants as comfortable as possible. There is nothing that I can think of that is more important, efficient and cost effective than mulching.
Research has shown that in the hot summer time mulching not only conserves moisture but can lower the soil temperature by as much as 20 to 30 degrees.
Temperatures of unmulched soil can reach well over 110 degrees and damage feeder roots.
Proper mulching is especially important for plants under stress, or newly planted ones without extensive root systems. To correctly apply organic mulches, such as the common shredded pine bark, to trees, start six inches from the base working out to the desired diameter. Depth should start at one inch at the inner circle, increasing to no more than four inches—two inches for clay soils—at the outer edge of the circle. Final depth may be reduced if landscape fabric is placed under the mulch.
Annual additions to mulch only should be made to maintain proper depth. Removal defeats one of the purposes of mulch, which is to decay and mix with the soil. Fluffing the old mulch before adding more will prevent it from forming a hard surface that deflects water, rather than retaining it.
Excessive mulch material piled up against the base of a tree or shrub, forming a mulch “volcano,” keeps moisture in direct contact with the bark. The moisture penetrates the bark and suffocates the cells of the phloem, which is the layer of living tissue that transfers food up and down the plant. When this supply of food from the leaves is limited, the roots die back. This leads to less water being taken up, and the tree or shrub goes into general decline, leaf drop and premature death.
If trees or shrubs have been mulched too heavily, remove excess mulch using a shovel, trowel or whiskbroom while taking care not to injure the trunk. A hard stream of water may be used to remove excess mulch and soil from the trunk and flared base. Cut off secondary roots that may have grown into the mulch. The trunk and flare should be visible. New mulch can then be applied properly.
Some of the same mulching principles apply to flowers and vegetables. It’s too easy to shovel huge fork loads over plants. Don’t cover perennials or you may smother them. This is especially true for shallow-rooted species. This is one reason to not mulch perennial beds too early in the spring before shoots emerge. Just as thick mulch will prevent weeds, it will prevent these plants from growing too. Mulching over peonies more than an inch or two may keep them from blooming.
Weed fabrics and black plastic are not useful for perennials, except perhaps in the first year. As perennials grow, they spread or get larger, and such fabrics can kill them. Such materials are useful for annual flowers and vegetables which will only be in one place for a year.
The mulching fabric can be used with annuals, or in vegetable gardens, with layers of newspapers—they are easier to lay if moistened—then covered with rotted sawdust or other organic mulch like cottonseed hulls. Of course, the organic mulches will rot and can then be tilled back into the soil, adding further organic matter back to your garden spot.