Tuesday, March 4, 2014
The End of Groundcovers
If I could banish one word from the English language, it would be "groundcover." The era of the groundcover must end. While this age of American landscape design has its roots in the Victorian garden, it has been the dominant landscape ethos since the post WWII housing boom. The primary idea of this era is that non-lawn planting beds need to be covered in a low maintenance, evergreen groundcovers such as English ivy, periwinkle, or pachysandra. The results of this philosophy on our landscapes are nothing short of catastrophic: millions of acres of meadow and forest have been decimated by these invasives, and weve forsaken the spiritually enriching act of gardening for the environmentally impoverishing act of landscaping.
The Rise of the Groundcover
Its easy to understand how groundcovers became so popular. As American suburbs sprawled away from city centers, individual homeowners quickly became absorbed in the enormous labor of maintaining huge expanses of lawn. With so much lawn to maintain, the rest of the yard needed to be relatively maintenance free. Planting beds were established where lawn wouldnt grow--typically in the shady areas under trees or at the edge of the lot. How to fill these leftover beds became a problem. Next to a manicured lawn, bare earth or mulch looks empty and unfinished, but filling these large areas with plants could be expensive. The groundcover became the magic cure. Tolerant of sun or shade, wet or dry, these low, creeping plants could be sparsely planted in a bed and left alone. Within a year or two, the bed was covered in lush carpet of glossy green ivy, the bright blue flowers of periwinkle, or the happy white spires of pachysandra. When maintained, the long flowing curves of planting beds created sinuous lines against the lawn, a declaration of the well-tended yard.
But the problem was that these yards were inevitably not well-tended. The very quality that initially drew homeowners and landscapers to these plants--their ability to spread--became the beginning of an aesthetic and ecological disaster.
Ecological Disaster
The honeymoon period (two or three years after the installation) yielded to the invasive period, and homeowners quickly realized that these low maintenance darlings actually required maintenance--lots of maintenance. The plants began to move and destroy: the ivies grew up trees and down slopes; pachysandra crept into a wet area and down stream channels; periwinkle moved across slopes choking all other vegetation in its path. Not even structures were safe. The clinging roots of ivies invaded mortar, the muscular branching of wisteria damaged buildings, and the thick impenetrable roots of periwinkle altered the hydrology of yards. [Image to left shows Vinca major, periwinkle, smothering a forest floor].
Often in suburban neighborhoods, the developer backs lots right up against undevelopable land like forested streams or adjacent woodlots. The groundcovers, unaware of property lines, spread into forests, streams, and meadows. Vines climb into the canopy, covering leaves and blocking photosynthesis. The additional weight of the vines often break branches and canopies particularly during snow. The understory invasives smother the ground-plane, preventing native plants from seeding and regenerating the canopy. Ecologists call the zones dominated by invasive groundcovers "ecological dead zones." [Image on right shows English ivy decimating forest floor and smothering trees.]The U.S. Forest Service now estimates that invasive plants like groundcovers strangle 3.6 million acres of national forests, an area the size of Connecticut. And thats just national forests. Invasive plants are thought to cover 133 million acres of federal, state, or private land, an area the size of California and New York combined. Each year invasives march across 1.7 million acres, almost double the size of Delaware.
An Alternative Concept
The concept behind groundcovers is as pernicious as the plants themselves. It is based on the mythology of the quick and easy, low maintenance yard. Groundcovers signal a disconnect between the owner and the land, a message saying "I dont want to deal with you". The professionals who use these plants, both designers and contractors alike, automatically assume the lowest possible expectations for that piece of land. Groundcovers are chosen based on the assumption that the area will be ignored, abused, or abandoned.
Groundcovers represent a failure of the imagination. Americans understand trees, shrubs, and groundcovers, but beyond these categories, were pretty much lost. We lack Englands rich garden history and thus fail to understand how to use herbaceous plants like perennials, grasses, annuals, or vines to enrich our planting beds. Native plant enthusiasts have long recommended native alternatives to invasive groundcovers, but their suggestions typically replace one type of plant with a less invasive counterpart (a vine for a vine, a creeper for a creeper). What these lists fail to do is to challenge the aesthetic that prompts the homeowner to use a groundcover in the first place.
The alternative to groundcovers is not slightly less invasive groundcovers, but planting beds filled with native biomass. We need to re-imagine our beds filled with a rich tapestry of perennials, grasses, shrubs, and low trees. While our unfamiliarity with these materials make them intimidating, we should rely on the toughest and most resilient native perennials and grasses to fill our borders. The demand for evergreen should be replaced with plants that provide winter interest: dried grasses, seed heads, and structural deciduous shrubs. We should transform our ecological dead zones into ecological hotspots by creating connected areas of native biomass. When we do this, we invite pollinators and birds back into our landscapes.
[Native biomass: Goldenrod and Echinacea fill a planting bed. These plants are low maintenance, provide nectar for birds and butterflies, and beautiful as they change through the seasons.]
A Model Project
Ten Eyck Landscape Architects in Phoenix recently completed an award winning project for a labratory building for the University of Arizona. The landscape around the building functions both as an outdoor classroom and a high performing native landscape. The project harvests water and provides and interface between students and nature. The former grayfield is now a thriving habitat for birds such as the roadrunner and hawks searching for ground mammals. The ASLA awards jury said of the project, "This project shows us everything that we should find in a university landscape. Not a blurred interpretation of "native" but rather a commitment to accuracy."
[Students enjoy a break at an outdoor classroom surrounded by vegetation native to the Upland Sonoran. Photo by Bill Timmerman.]
And Im including one additional image to show how native grasses can be used as a groundcover alternative. This photo taken at Chanticleer Garden in Pensylvania by Rick Darke.
[Native grasses such as Prairie Dropseed, Sporobolus heterolepsis, make an ideal alternative to invasive groundcovers. Photo by Rick Darke.]
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