The use of mulches affords gardeners many benefits. Cypress mulch, the shredded bits of tree bark and younger branches, is harvested from bald cypress and pond cypress trees (Taxodium distichum and Taxodium ascendens). In the American southeast, this organic mulch is common and relatively inexpensive. The dyes used to color this mulch is merely ornamental, not providing any advantage to the soil or the plants growing in it. Many don't use cypress mulch for fear it promotes the destruction of native cypress tree stands.
Soil Moisture Retention
Cypress mulch, when maintained at a depth of 2 to 4 inches, diminishes the loss of water from the soil by evaporation. Moist soil is also shaded by the mulch, keeping soil temperatures cooler and reducing the rate at which evaporation occurs. Sandy soils naturally lose moisture more quickly than loam or clay soils.
As long it is free of weed seeds, the cypress mulch particles will carpet the soil and shade it, preventing the germination of seeds and growth of undesirable plants in the landscape bed.
Moderated Soil Temperatures
With a layer of cypress mulch, the soil's temperatures are kept more uniform according to the University of Florida. The shading of the soil in summer prevents the top inches of topsoil from heating up in sunshine, resulting in potentially more evaporation or water uptake needs by the plant roots. Conversely, in cold weather, the mulch insulates the soil from colder air temperatures and can block the warmth of the soil from radiating out to the air.
Cypress mulch, like other organic mulches, degrades naturally over time, adding both humus material and trace nutrients to the topsoil. Plants use the nutrients. The addition of humus from decayed cypress mulch improves the texture and "crumble-ness" of soil as well as help retain moisture in sandy soil and improve water drainage in clay soil.
Healthier Plant Roots
Garden plants surrounded by decaying cypress mulch will produce surface roots in the mulch that surrounds them. These roots are produced in addition to the roots that a plant spreads in the topsoil. Consequently, mulched plants produce more roots than unmulched plants, according to the University of Florida.
The fine-texture of cypress mulch creates a uniform top dressing for areas across a landscape. With the suppression of weeds, a pleasant, natural-looking mulch is seen as a ground cover among plants and visually unifies a landscape and makes it look well-kept and professionally presented.