Back to Nature
The greenest approach to landscaping returns a yard to its roots
This Old House landscape contractor Roger Cook and crew in the eco-friendly yard of Austin house project
Michael Klug and Michele Grieshaber wanted to live in a green house, a home that would have as little impact on the planet as possible. Sensitive to the effect their consumption of natural resources has on the environment, they worked with a green architect, hired a green builder, and asked This Old House TV to help them remodel their 1926 Craftsman bungalow using recycled materials, energy-saving systems, and eco-friendly building methods. But their green ethos didn't stop at the four walls of their house.
This being Austin, Texas, the weather is temperate enough for residents to enjoy the outdoors most of the year. So the couple applied their green thinking outside the house as well, turning their generic suburban yard into a sustainable landscape.
Rather than being designed primarily for show, a sustainable landscape is more about function: providing food and cover for birds and butterflies, protecting water resources, and reconnecting city dwellers with the natural world. The plants are suited to the climate and soil, so they require less care to thrive, and hardscaping materials impact the ecosystem as little as possible.
Roger Cook, This Old House landscape contractor, says homeowners are becoming more interested in eco-friendly yards. "Everyone is aware of the effects of fertilizer and pesticides and where they go when they leave the lawn," he says. "People question plant choices, looking for native alternatives, and ask 'How can I maintain my yard organically?'"
To reimagine their small lot, Michael and Michele hired local landscape designer J. Adams Kirkpatrick. Out went problem plants, and in came native species and efficient drip irrigation. The lawn shrank. Impervious paving made way for gravel that lets rain seep through. And a new rainwater harvesting system went in to free the landscape from its dependence on city water. The design was so eco-friendly, in fact, it garnered the team a Green Garden award from the City of Austin.
What the couple did is actually quite simple—doable for any homeowner hoping to reduce the negative effect their yard might have on the environment. Here are five keys to their plot's sustainability.
The skinny twig of a tree in the center is a Texas redbud discovered after overgrown nonnative plants were pulled out. It should flourish surrounded by new native plantings.
Planting What Grows Naturally
Shrubs, perennials, grasses, and other plants that are native to a particular region are naturally adapted to the climate and soil, so they require less prep and upkeep. They are also in sync with local wildlife, so one may bloom just as migrating hummingbirds arrive and need nectar, while another opens when a specific native bee is most active.
Michael and Michele's old yard already had a handful of natives, including a couple of hollies (Ilex vomitoria and I. opaca), Texas wisteria (Wisteria frutescens), and a pecan tree (Carya illi noinensis). Kirkpatrick added many more, including American beautyberry (Callicarpa Americana), which has neon-bright violet berries that birds love, and Texas betony (Stachys coccinea), which attracts hummingbirds.
Just as important as planting native species is removing nonnatives that can become invasive. When a plant adapted to one environment is put in another, there's always a gamble that it might wind up growing unchecked because there aren't the limiting factors—temperature highs and lows, animals that feed on the plant—that exist in the old environment. Michael and Michele's old landscape, for instance, included waxleaf privet (Ligustrum japonicum), which gardening books generally describe as suitable for topiary or bonsai. But in Austin, it grows to tree size and drops limbs. Birds have carried the seeds to streams, where it's shading out native vegetation. Sadly, the fruit doesn't even give the birds the nutrients they need. "We now have acres of silent forest because invasive plants nudged out the species that sustained the birds," Kirkpatrick says.
He ripped out both waxleaf privets in the yard and replaced one with a loquat tree. Near the other, he found a Texas redbud growing in the same area. Though it's barely a stick, he expects it to fill out now that the bully plant is gone. (Kirkpatrick did include some nonnatives on his plant list because they were proven to be tame species that had adapted to the local climate but wouldn't spread aggressively.)
Adding plants that provide food to birds and animals is another way to keep the local ecosystem in balance. So Kirkpatrick also included dwarf Barbados cherry (Malpighia glabra), whose berries feed birds; southern wax myrtle (Myrica cerifera) and inland sea oats (Chasmanthium latifolium), with seeds that mice and rabbits like to eat; and purple coneflower (Echinacea purpurea), which attracts butterflies.
A landscape crew member rakes pine-straw mulch over the plant beds. The native material keeps soil moist, shades out weed seeds, and nourishes plants as it breaks down.
Feeding the Earth
Trying to garden in poor soil is a never-ending battle, the antithesis of what a sustainable landscape should be. Rich soil makes for healthy plants, including turf, which means fewer diseases and pests and consequently less need for chemical intervention. Michael and Michele's native soil is "black gumbo," an elastic clay that swells in the rain and shrinks during dry spells. But many plants thrive in it, provided enough organic material is mixed in so it drains.
Amending the soil is particularly important after construction, notes Roger. "Plants can't grow in some of the junk that's left behind," he says. "You need to till compacted areas and add organic material to get the soil back into shape."
Mulch and compost can play a major role in protecting the earth. By shading the soil, mulch keeps moisture from evaporating and deters weed seeds from sprouting. In the couple's yard, Kirkpatrick opted to use pine-straw mulch, which feeds plants with nutrients as it breaks down.
In the vegetable garden, he built two tall compost cones out of metal stakes wrapped with wire. Fruit and vegetable scraps and leafy yard waste go in at the top; nutrient-rich compost "tea" seeps out into the garden underneath—or the couple can take compost from the bottom to spread in the rest of the yard. It's a tidy approach he hopes will encourage the couple to keep up the organic recycling.
Minimizing the Lawn
Lawns warrant special attention in a sustainable landscape because they tend to demand more water, fertilizer, and care than other planted areas and because they don't offer much in the way of wildlife habitat. Yet many people still want a green lawn, whether as open space or for recreation. Michael and Michele didn't want to eliminate theirs entirely, but they did make it smaller, to serve almost as a walkway, with deep planting beds around the edges.
Besides amending the soil with compost, there are four keys to making a lawn as sustainable as possible: watering efficiently, mowing appropriately, using only slow-release organic fertilizers, and planting the right variety of turf grass. In Austin's hot climate, buffalograss is the most sustainable option; it needs watering just once a month and mowing only once or twice a year. But it doesn't stand up to foot traffic, and it can take up to two years to fill out and mature. So Kirkpatrick recommended St. Augustine grass, which is also a good choice for their shady site. The couple plans to mow it high and leave the clippings on the lawn to encourage deep root growth, which helps keep the soil porous.
David Krug, Michael's son, checks out the St. Augustine sod on a small patch of the front yard. He and his brother, Sam, are avid gardeners.
Managing Water Use
In most gardens, rain coming off the roof can be a problem, damaging plants and overwhelming storm drains. But at Michael and Michele's, it's a resource. Austin gets 32 inches of rain in an average year—nearly as much as Seattle—but it comes in spurts between long, hot dry periods. As a result, most plants, other than true natives, need irrigation. That often means using municipal water.
To reduce that dependency, the couple installed a rainwater collection system with help from Innovative Water Solutions. Like the rain barrels that many homeowners use, their system collects gutter water. But while typical rain barrels hold 50 to 80 gallons, Michael and Michele's epoxy-coated, galvanized cistern, which sits aboveground, holds 1,200 gallons and feeds most of the irrigation. The capacity will depend on how full the tank is at the beginning of each storm, but it has the potential to collect nearly 30,000 gallons in a year.
Water is drawn through a floating filter 8 inches below the surface, rather than from the bottom of the tank where debris collects. The tank is also plumbed for city water so that the irrigation system will work when the tank is empty. And there is a pump to boost the water pressure up to the 40 psi needed.
To make every drop count, Michael and Michele are using drip irrigation, which delivers moisture to roots in just the quantity that each plant needs. Sprinklers still feed the lawn, but everything else now gets water through a combination of drip hose and 6-inch-tall emitters that are fed by underground tubing. The emitters deliver a precise amount of water to specific plants—1 gallon per hour for one, maybe 3 gallons for another. And an electronic control allows the couple to adjust the system to suit the weather.
Using Sustainable Hardscaping
Before subdivisions blanketed the land, rainwater fell on meadows and forests and gradually percolated into the soil. Some worked its way into streams, while the rest pooled in underground aquifers, which today supply the wells on which many communities depend. Sustainable landscapes attempt to preserve what's left of this natural water cycle by keeping impervious paving to a minimum. This allows more rainwater to soak into the soil, rather than draining off quickly.
Michael and Michele's old backyard included a concrete walkway. Now that's gone, replaced by pea gravel. The path is lined with blocks of limestone, which is quarried locally—a "green" plus because it cuts down on fuel needed for transportation. Kirkpatrick also recycled chunks of the old concrete, setting them as stepping stones down the middle of the path so Michele can take kitchen scraps to the compost area in her bare feet.
In the side yards, paths are "paved" with pine straw collected from woods near Austin—the same material used to mulch the plant beds. Up against the limestone and juxtaposed with the locally adapted plants, the straw adds to the natural appearance of this deceptively well-planned landscape. With as little maintenance as possible, this yard will function the way the landscape in Austin would without the presence of people—just the low—impact plan Michele and Michael were going for.