Choose a variety of native species
Native plants are hardier and better adapted to your particular region, and survival is key—dead plants don’t continue to capture carbon. The right plants should have a better chance of surviving your local weather, though research has not clearly shown what will happen as it becomes increasingly worse. Not every tree and shrub can be drought-hardy, flood-tolerant, and freeze-resistant at the same time. But a garden with a variety of native plants will have a better chance of making it through the next few decades. The standard American lawn simply captures less carbon than many other plants. It’s better than concrete, but mowing keeps both the upper part of the plant and the roots short—the more plant there is, the more carbon it can hold. Producing massive amounts of fertilizer for millions of acres of lawns is also a carbon-intensive process. Even more, lawns are a huge drag on our water resources, especially in drier areas. The solution is a garden that works for you and the environment, with better aesthetics and none of the baggage of the standard lawn. If you saw our ground cover story, a carbon sequestration garden is an amped-up version of that. Here’s how to make it. If you’re not sure where to start looking for native plants, Doug Tallamy, a professor of entomology at the University of Delaware, has created a website where you can enter your zip code and learn about the native flora in your area. Local extension services and nurseries are also great resources that will help you understand what will work in your community.
Consider trees, but also native grasses
If carbon is protein powder, trees are bodybuilders. Trees are about 50 percent carbon by dry weight (after you remove the water). That’s a big carbon offset bang for your real estate and actual buck, according to Eli Sagor, an adjunct faculty extension specialist at the University of Minnesota. But trees don’t work in every area. Grasses and prairie species can also gobble up a lot of carbon. Even if you don’t have access to trees, you can aim to find plants with as large of a root system as possible. “I live in Minnesota, and some of the prairie species are famous for having roots that go 6 to 10 feet deep in the ground. Really, quite surprisingly deep,” says Sagor. “And that brings carbon deeper down into the soil profile and stores a lot more carbon underground.” Gerlinde de Deyn, a soil scientist from Wageningen University, also sang praises of the grasslands. Unmowed grasses might not seem to be taking up much space above the soil, but there’s a lot going on underground. And since most of these plants are perennials, the carbon they gather won’t go anywhere for a long while. Having a variety of native grassland species is best because their roots will reach different depths, de Deyn says. When these die, they are eaten by microbes and worms that also die, and some of their carbon becomes part of the soil, especially if the dirt has clay, loam, or other “sticky” substances that can store the carbon. “That’s a relatively recent finding that, hey, also, relatively new carbon can still be stabilized in the soil,” says de Deyn.
Use natural fertilizer
Making chemical fertilizers uses a huge amount of greenhouse gases, and, like lawns in general, the finished product is bad for the environment in multiple ways. But if you’re using the right combination of plants, you might not need synthetics. De Deyn suggests planting legumes, which have bacteria that naturally convert atmospheric nitrogen into nitrogen-based nutrients plants need. Fixing nitrogen in the soil also increases the amount of carbon stored in that soil, probably because the element makes the plants more efficient carbon sinks.
