The biggest obstacle to low-impact, eco-friendly gardening is our way of thinking, shaped by ideas that the lawn should be the main landscape feature, that every pest and disease needs eliminating and that there is a product that will fix all your problems.
But surely to be a gardener is to be someone who derives deep satisfaction from nurturing nature. We need to contemplate not only our carbon footprint but also our greater cost to the environment. Consider what we are bringing onto our property and what is leaving it.
As the arrival of spring gets our own sap flowing, we offer a gentle guide to gentler gardening. (My thanks to the following horticultural experts: Ray Mims of the U.S. Botanic Garden; Fred Spicer of the Chicago Botanic Garden; Todd Forrest of the New York Botanical Garden; Jon Traunfeld of the Maryland Home and Garden Information Center; and Paul Tukey of Glenstone Museum.)
One of the great shifts in gardening in recent decades has been the awareness of the importance of the soil, its structure and its biology, and the need to cultivate both. This may have been the sentiment of organic gardeners all along, but now we all have a greater understanding of this hidden biosphere and its symbiotic relationship to plants, especially the way that abundant colonies of beneficial bacteria and fungi in the soil help feed plants and keep them healthy.
Fungicide sprays and fertilizer salts will harm this soil zoo, critics say. And the way to feed it is to add organic matter. A compost pile will keep green waste on site and, properly managed, soon provide finished material for soil amendments. If you don’t want to go to the trouble of building and maintaining a compost pile, you can keep, shred and store fallen leaves, which are a valuable commodity. Leaves on the lawn, provided they are not too thick, can be shredded in place and left; they will disappear by spring.
Plants, including turf grass, need nutrients to grow and thrive. But synthetic fertilizers exact a toll on the environment in different ways. Nitrogen and phosphorus manufacture requires fossil fuel energy, which releases greenhouse gases into the atmosphere. The leakages of methane from fertilizer plants may be much higher than thought, according to a recent study by the Environmental Defense Fund. Methane, though not as long-lived in the atmosphere as carbon dioxide, does more damage, said Joe Rudek, a lead senior scientist at EDF.
Although big farms rely on synthetic fertilizers to grow food or livestock feed, he said, “there’s no reason I know of for gardeners to be buying inorganic fertilizer.” Organic fertilizers are available, including products made from fish or seaweed.
The second harm comes when fertilizers are applied to farmland and landscapes, only for some to be washed into waterways to the detriment of receiving bodies of water, such as the Chesapeake Bay or the Gulf of Mexico, and their ecosystems. Maryland law limits the amount of nitrogen residents can put on their lawns, restricts the timing of applications (not in winter, basically) and permits phosphorus feeds only if a soil test shows a need.
Old-fashioned compost tea was a passive concoction of compost or aged manure left to soak in a can of water for a few days. Today it is more likely to be a sophisticated brewed organic product. Home gardeners can make their own versions by investing in some equipment and devoting themselves to its manufacture. Optimally, a mesh bag filled with high-quality compost is placed in a tank of water and aerated for a day or two. The ensuing microbe-rich brew is then sprayed as a soil tonic to build populations of beneficial microbes, reducing the need for fertilizers. Its full value is debated — some say compost tea makes plants so healthy they shrug off diseases — but almost everyone agrees it invigorates plants.
The problem with many pesticides is that they kill beneficial (or merely neutral) organisms that you are not targeting; this extends to systemic pesticides such as neonicotinoids or organic pesticides such as pyrethrins. “I like to say cobra venom is organic,” said Forrest, vice president for horticulture and living collections at the New York Botanical Garden.
Gardeners who are trying to provide habitat for wildlife or encourage pollinators cringe when neighbors have their yards sprayed for mosquitoes. The best way to combat mosquitoes is to remove sources of standing water, where larvae develop. In ponds, you can add fish, which eat the larvae, or apply pellets of Bti, a natural larvicide.
Rudek knows firsthand the effects of mosquito pesticides. He lives on a one-third-acre lot in suburban Philadelphia, where he kept honeybees. The township came along his street to spray for mosquitoes. “It killed my bees, immediately,” he said.
Many pests can be handpicked and dumped in a bleach solution; they can be sprayed individually with a bottle of insecticidal soap, and some can be vacuumed up.
Lawns are useful and have a visual appeal, but they are the most dependent areas for fertilizers, pesticides and precious water.
If you want a lush, manicured lawn, “then you owe it to yourself and to the world to understand what you’re putting on the lawn and what your contractor is putting on the lawn, what they’re doing to the environment,” Forrest said. “Make sure you make an informed decision.”
Most lawns can be reduced in size and still provide a place for the kids and the dog to let off steam. You can also do what a lot of major botanical gardens have done and ease up on lawn perfection for the sake of the environment, tolerating more dandelions or clover, for instance.
This has also been the case at Glenstone Museum, the privately owned, public art campus in Potomac, Md. Its entire 300 acres of turf, meadow, woodland and streams are managed organically. This extends to the more than 20,000 annuals plugged into the Jeff Koons sculpture “Split-Rocker” annually. Before planting in the spring, they are soaked in a bath of water containing mycorrhizal fungi, the sort that lives in the plant root zone.
Glenstone’s lawn areas have been reduced from 16 to five acres, much of it replaced with meadow, and the turf that remains has been tested for pH, levels of nutrients and organic matter, and managed organically. Tukey, Glenstone’s chief sustainability officer, shows me a storage shed with large compost tea brewers and shelves of fish emulsion, a concentrate made from crab shells, and insecticidal soaps. The groundskeepers make and spray 500 gallons of compost tea daily.
“The message at Glenstone is: Going organic doesn’t mean going ugly,” Tukey said.
Another EDF scientist, Eileen McLellan, said just as farmers are encouraged to plant buffer zones between their fields and ditches, to intercept fertilizer runoff, home gardeners can create a planting strip or a rain garden on the edge of their lawns. “You can have significant environmental benefits by removing part of the lawn,” she said. “You don’t have to take the whole lawn out.”
Weeds are a symptom of a poor lawn, not its cause. Common factors for lawn failure are too much shade, compacted soil and the related problem of standing water. If you can’t fix the shade or the waterlogging aspects, plant something else.
Here’s another important consideration: The prevailing lawn grass in the Mid-Atlantic is turf-type tall fescue. It is a cool-season grass inherently unhappy in high summer, especially a dry one. (Warm-season grasses have their own issues.) When you renovate or overseed such a lawn, best done in late summer, it pays to seek out a variety of fescue that has been bred for these conditions. Don’t just pick up a bag of seed thinking they’re all the same.
Many natural areas have been significantly degraded by the rampant spread of invasive plants, whose untended populations exploded and have outpaced the resources of land managers. Many of these plants escaped from gardens via seed-scavenging birds.
These include the vines English ivy, oriental bittersweet, porcelain berry, wintercreeper, Asian wisterias and honeysuckles. Problem trees and shrubs include ailanthus, callery or Bradford pear, autumn olive, bush honeysuckles, winged burning bush and Japanese barberry.
Remarkably, some of these plants are still sold in garden centers, so you can’t assume that what you’re buying behaves itself. If you have these in your garden already, consider removing them or, at a minimum, making sure they don’t go to seed. Cut off the fading flowers and, in the case of the vines, don’t let them loose on trees.
There is the idea that if you put in native plants, they will take care of themselves, but this is not strictly the case, as anyone who has tried to grow a mountain-laurel or franklinia tree will attest.
What is more important is that you select plants based on their preferred growing conditions, whether sun or shade (and the degree of each), the soil types and pH, and whether the site is wet or dry. Planting a yew or a cherry-laurel in heavy wet clay that is then mulched and irrigated may well lead to root rot. Before planting anything, dig an 18-inch-deep hole and fill it with water. How fast does it drain? Five minutes or five hours? Your local county extension agency can tell you how to get soil tested for fertility, pH and amount of organic matter.
In sum, you have to learn your site and your plants. Don’t assume a shrub in glorious bloom at the garden center will thrive in your yard. A tree or shrub in a place it doesn’t want to be may hang on, but it will be stressed and attract pests and diseases, for which constant spraying is not the answer. A moisture-loving plant may require continual watering, especially in a drought. Once established, the right plant in the right place will be better placed to survive dry spells.
Supplies and equipment
Your neighborhood nursery carries plenty of pitfalls for the green gardener. Among them:
Don’t buy cheap, flimsy tools that will soon need replacing. Garden tools that are well made are investments that last for many years.
Plastic nursery pots accumulate at an alarming rate for serious gardeners and should be recycled. Some can be used for seed starting or for perennial divisions that can be given to friends.
Sphagnum peat moss is a common ingredient in potting mixes and soil amendments, but many gardeners are moving away from it because it is harvested from ancient peat bogs that function as important carbon sinks. Alternatives include mixes made from coconut fiber (coir), highly screened wood and bark compost, and shredded paper products.
If you are using wooden planks to create raised beds or to shore up hillsides, check out architectural salvage yards for recycled lumber. I avoid pressure-treated wood in the vegetable garden, content to use untreated pine as a short-lived option, or I use cedar with its natural rot resistance.
Gas-powered garden equipment is not as clean as automobile engines, especially two-stroke versions found in chain saws, leaf blowers and edgers. The way to minimize their emissions is to keep them well tuned and serviced. Electric-powered tools are kinder (to the environment, not the ear) but even they rely on fossil fuels for their power generation. Consider ditching the leaf blower this fall for a good garden rake and a broom, especially now that you are going to keep all those leaves on site.
More from Lifestyle: