How to Make Your Backyard More Biodiverse

From the Middle English word launde, "lawn" once referred to an area of short grass or other ground cover which allowed medieval castles an unobstructed view of the surrounding area. Those lawns soon morphed into the highly manicured gardens of French and English royals and thrived in the wet climates of the United Kingdom and Western Europe. However, the vast plains and deserts of North America are ill-suited for these over-groomed grasses. For nearly 500 years people have attempted to recreate those medieval castle gardens, all while depleting groundwater and displacing native plants and animals.

Grass lawns cover more than 60,000 square miles of the United States, approximately the size of Washington State. Lawn irrigation amounts to nearly 9 billion gallons of water per day in the summer. Much of that water isn’t absorbed by the sod or Kentucky Bluegrass. Instead, it evaporates or runs directly to the sewer. As a result, lawnmower use lends itself to 5% of the United States’ air pollution, not to mention the nearly 600 million gallons of gas used to mow lawns each year.

And while it’s true that grass can sequester carbon when managed well, native grasses and other, less water-intensive landscape options can have between four and 10 times the sequestration power of average lawns. Biodiverse yards, which should always include native flora, also attract essential pollinators and provide habitat for everything from insects and small rodents to deer and songbirds.

You don’t have to tear out every blade of grass to start making your backyard more biodiverse. Just the perimeter of your yard can be enough room to build vital pollinator habitat, and it is even possible to seed an entire meadow into your existing lawn, should you choose to do so.

Site Evaluation When choosing any plant for your yard, it’s essential to know what kind of soil you’ll be working with and how much sun and moisture it receives. Weeds are often a good indicator of what’s happening below ground. Large, healthy weeds and a lawn that stays green throughout the summer are markers of rich, fertile soil. On the other hand, small scraggly weeds suggest that the soil is dry, sandy, or dead, which is not necessarily a problem as long as you choose plants that can survive in those conditions.

Sun and moisture should also play a role in plant choice. Try to find an area that receives sun for at least half the day. If that isn’t possible, focus on finding shade-tolerant plants. Look for soil moisture indicators, such as pools of standing water after rain or evidence of run-off in dry soil. Regardless of how much (or little) sun and water your yard receives, you must choose plants that are best suited to your yard’s specific climate.

Picking Plants Knowing your hardiness zone can get you on the right path in choosing plants native to your area since those are most likely to thrive in your specific climate. Hardiness zones are based on average annual extreme minimum temperatures and range from 1 (coldest) to 13 (hottest). You can find a hardiness zone list on the USDA website.

After determining which zone you live in, it’s a good idea to choose perennial plants native to your area. Perennials are especially important because they are both self-propagating, meaning you only have to plant them once, and they grow long roots which allow them to sequester more carbon and build soil structure. Native plants are important for several reasons. First, because native plants are adapted to the local environment, they don’t need herbicides, pesticides, or fertilizers. Second, they will attract pollinators such as native bees and songbirds. Lastly, native plants are not likely to overtake your yard as they are uniquely adapted to coexist with other native varieties. Conversely, non-native invasive plants can quickly take over a patch of ground by outcompeting other plant varieties and destroying existing biodiversity.

When choosing starter plants, you will have more luck finding native species at your local nursery rather than at a grocery or hardware store. Big-name stores typically carry non-native species, likely treated with herbicides and pesticides chemicals during the growing and shipping process. Many non-organic flower varieties receive a treatment of neonicotinoids which are fatal to bees. Your local nursery will have native varieties better suited for your climate and should be able to help you choose what you need to build a biodiverse yard. Your local extension office’s weed department may also be able to help you select native species to plant as well as identify invasive plants on your property.

Several seed companies specialize in native and heirloom seeds suited to specific areas if you’re planting from seed. Heirloom seeds have been handed down for generations and haven’t hybridized with other plants. As a result, heirloom plants foster biodiversity even among the same type of plant, providing varied food sources for pollinators and other fauna.

Dealing with Pests A biodiverse yard can also mean biodiverse pests. Herbicides, pesticides, and fertilizers can harm not only pollinators and any other animals or humans in your yard, but they also severely damage the soil on a microbial level, making it nearly impossible to maintain any semblance of biodiversity.

To maintain healthy and robust biodiversity, use as few chemicals as possible in your backyard. If you notice an overabundance of flying insects, try installing bird nesting boxes and bat houses on trees or fence posts. If small rodents are a problem, try building an owl nesting box (castor oil powder is also effective at deterring voles and mice). Just keep in mind that while mice, ants, and mosquitoes can be annoying, they are all just proof that the biodiversity of your backyard is improving. The more, the merrier.