One of the most powerful addictions of the gardener is mulch.  Just as you would vacuum and dust for company, the gardener mulches.  In addition to its healthy attributes, mulch is the major component in defining the boundaries of a garden.  By mulching, the gardener makes a bold statement, "This is my garden!  The rest is that which I have not conquered."

    Let's first talk about proper mulching techniques.  One of the worst mistakes in landscaping is "over mulching" or mulching too deeply.  In the 1990's, it became very popular to mound mulch very high around the trunks of trees to give what I call "mushroom cap" appearance.  The piling of mulch 6 to 12" deep around the base of plants has become common practice.  This practice is a major cause of death in the landscape because the original roots are inches below the surface and the mulch holds moisture constantly against the bark of the plant.

    The depth of the mulch may hold moisture in the soil for a long period of time, but if the actual soil becomes dry under 6 to 8 inches of mulch, then a desperately needed inch of rain does not penetrate the mulch, let alone rehydrate the dry root system.  The roots of the plant may even leave the soil seeking moisture in the mulch.  This leaves the roots vulnerable to higher temperatures and a greater level of moisture fluctuations.

    Piling mulch deeply around the bark of a plant can easily rot the protective layer of bark off of the trunk of the tree.  Under the bark lies the cambium layer of the plant's vascular system.  The cambium layer is responsible for the transmission of fluids and nutrients both up and down the plant.  The bark protects the cambium and kill the tree.  The exposure of the cambium is why "weed eaters" kill more plants than any other factor.  "Lawn mower blight" or mechanical injury accounts for more than half of the deaths incurred in the landscape.

    In the 1990's, universities declared that plants in heavy soil should be planted in a shallow manner so that the roots would have better drainage.  I agree with this principle, but I still put the roots of my plants in the soil where a reservoir of moisture and nutrients exist.  I think some folks capitalized on this high planting method by knocking off a six inch square of sod and planting the tree in mulch.  Excuse me, I don't think this, I know so for I have seen this murder in the landscape.

    Mulches consist of pine bark chips of various sizes, shredded bark, pine needles, cocoa shells, recycled tires, and so forth.  I will probably write another column later to distinguish between all of these mulches, but for today I've gone on long enough.  Here's a hint of my personal preferences.  I prefer a fine pine bark mulch because it drains well, looks good, and decays quickly into the soil to provide much needed organic mater.  I could go on a bit longer about mulch if I was a bit more impassioned by the subject, but I'm sure we all have work to do this week!