When it comes to mulch, green is the new brown.
Instead of spreading bark, peat or straw over your planting beds, consider planting a living mulch that will spread itself over your bare soil, keeping it cool and moist while also adding a lushness that is more attractive than conventional alternatives.
Some prominent landscape professionals are embracing the idea, saying real plants are more attractive and better for the environment.
“Bare ground is an abomination against nature,” said Curtis Short, an aesthetic pruner and gardener in Sonoma County who has long been a cheerleader for the virtues of mulch in its many forms.
Green mulch was a hot topic at Pacific Horticulture’s “Changing Times, Changing Gardens” summit in Santa Rosa last fall. Thomas Rainer, a landscape architect in Washington D.C., who has designed projects for the U.S. Capitol grounds, the Martin Luther King, Jr. Memorial and the New York Botanical Garden, devoted his keynote address to the concept.
Rainer advocates creating a meadow that carpets the lower several inches of your entire landscape, while an arrangement of larger, discrete shrubs, trees or large, stout perennials, flourish above. Good bottom story plants in this region include anything from California poppies and society garlic to bleeding heart, snowberry and redwood sorrel.
Short came away a convert.
“I admit I am a big proponent of using mulch chippings, but I see them as a way to feed soil and defend against weeds while more desirable plants take hold,” he said. “I never intend a mulched area to remain plant free unless there is good reason for it to remain open.”
While more and more homeowners are wisely ripping out their lawns, they’re replacing them with landscapes that tend to be filled in with a lot of bark and pebbles.
“These are not ideal lawn substitutes because the world is a better place when ground is covered by a mulch of plants,” Short said. “If you have ground that is not paved with concrete, flagstone or pavers, then plant it. Those plants will sequester carbon, release oxygen, out-compete weeds, create habitat, improve the soil and beautify our world.”
Sherrie Althouse, the co-owner of California Flora Nursery in Fulton, said the idea makes sense on many levels, including weed suppression.
“To fill in with desirable plants that have traits you enjoy makes more sense than allowing weeds to come in that are opportunists that will take over the whole place,” she said. “As a gardener you get to be the one that makes the choice.”
Rainer has pointed out that plants are social creatures that in nature, live in communities. And yet so many gardens are filled with plants installed in isolation within what he has described as “a sea of mulch.”
A layer of living green material can also protect the soil from erosion, particularly on slopes, said Diana Douch of Artemis Design and Gardens in Sonoma County. And any additional water consumed by plants used as green mulch is offset by the moisture retained when the soil is shaded, which in turn provides a welcoming environment for lizards, worms and soil microbes that like cooler soil, she said.
Before planting, prepare the soil by digging it over to the depth of a fork and then, as she says “let the worms do the rest.” After that, add some organic soil amendment and dig it in for priority planting. After you have planted, add another 2-3 inches of mulch to suppress weeds while the new plants grow and spread.