‘Living’ mulches is a more healthy alternative to bark
We need to consider our use of mulch. What is mulch and why is it used? A mulch is anything used to cover bare ground. A mulch covering is used to suppress the growth of weeds and prevent the loss of water by evaporation from bare soil.
A uniform mulch covering visually unites the separated plants in a landscape, prevents extreme swings of soil temperature, prevents the soil from caking and drying and provides myriad other helpful functions depending on the type of mulch used and the needs of the homeowner.
Problems arise because mulching material is applied incorrectly or the wrong material is used. Forty years ago, the mulch used was the bark stripped off trees at lumber mills. It was a waste product. Over four decades, the dynamics have changed. Bark mulch has become a marketable product. Wood may be triple-ground and dyed for use everywhere.
We need to be aware that there are few definitions governing the sale of wood mulch. Wood waste can come from construction projects, building demolition, shipping pallets or other materials that in the past ended up in landfills. We also should be aware that you are unlikely to see wood mulch used in landscapes in England, Ireland, Europe or the Orient.
What do they use as we use mulch? They make use of living mulches. Think of living mulches as groundcovers that self-renew, self perpetuate, perform environmental functions and add ecological and aesthetic dimensions as well. They are sustainable.
Depending on the site and the existing planting, moss can be utilized as it is in famous landscapes in England and Japan. If an evergreen “mulch” is needed, consider the use of ivy (hardy English), Vinca (blue or white flowers), Pachysandra (Allegheny or Japanese Spurge), or native plants like Partridgeberry, Bunchberry (Cornus canadensis), Ginger (Canadian or European), heaths and heathers, or visit Garden In The Woods to view a living catalogue of native hardy plants.
If you wish to broaden your palette, look to the wealth of deciduous groundcovers to use between and under shrubs and trees. Ajugas with white, pink, blue, or purple flowers and leaves of various colors, Lady’s Mantle (Alchemila), Lily-of-the-Valley, some of the Astible, Epimedium, ferns, Lamium, Ground Phlox, Veronica, Carex, Liriope, Waldsteinia (Barren Strawberry), Thyme in great variety, as well as the Sedums and Hens and Chickens that can be used in hot, dry, sunny locations.
Aged sawdust or cocoa beans may be used, but never more than 1 inch deep, as both form an attractive mulch for annuals and small perennials. Clean hay (free from weedy plants) is well used in vegetable gardens, as is thin applications of cut lawn grass.
I do not recommend fiber mats or black plastic, as both inhibit the free movement of water into the soil and the exchange of soil gases with the atmosphere. A functional mulch should be loose and open. For the same reason, bark mulches should never be applied more than 4 inches deep and never in contact with living plants.