SEEDED NATIVE LANDSCAPES
By: Jordan Wilkinson, Designer at DG2 Design Landscape Architecture
Generations ago, most of the American Midwest was dominated by a prairie landscape full of tall grasses and colorful wildflowers. This vast area of thick topsoil and enormous ecological diversity was the result of ancient glaciers melting and retreating, leaving fertile soils behind. Along with the vital combination of grazing animals and natural fire, these prairie landscapes recharged themselves and thrived for thousands of years until modern agriculture was realized. If you have never experienced the beauty of a native prairie, travel to one of the few untouched remnants remaining in the Midwest and see for yourself. The Flint Hills ecoregion in Kansas is particularly breathtaking and changes visually throughout the year. Any self-respecting K-State Alumni will agree with me.
What are the most important issues on Seeded Landscape Projects?
This past week DG2 Design was lucky to attend the latest Shaw Series for Stormwater + Landscape Professionals, which consisted of a tour of multiple seeded prairie landscapes in the St. Louis area. These destinations included the Alberici Headquarters, SSM St. Clare Campus, Shaw Nature Reserve, Meadowbrook Country Club, and the Donald Danforth Plant Sciences Center. The tour was extremely informative and shed light on some of the most important issues to address as a designer specifying a seeded landscape on a project. These issues include the window of planting, method of planting, addition of cover crops, and maintenance techniques to establish a successful seeded landscape.
Most native grasses and forbs require a period of cold stratification to successfully germinate in the spring. This means planting the seeds during cold weather – basically any time after Thanksgiving and through March. December is a great time to plant these seeds, as a decent freeze thaw cycle will help to get them started. If a project schedule does not align with this window, seeds can be artificially stratified in a refrigerator for several weeks before planting. Once the seeds are ready to be planted, the pros say to include a coating of a diverse blend of mycorrhizal fungi inoculant at the time of installation. This not only seems to help produce a much more vigorous success rate, but also maintains forbs as the landscape matures.
The use of a cover crop, also known as a nurse crop, is another key tool to use to ensure success with a native seed mixture. Cover crops such as Canada Wild Rye help in areas prone to erosion because they germinate quickly and hold the soil in place long enough for the prairie seeds to grow. Cover crops also help to reduce the influx of invasive and undesirable weeds in the planting area. Weeds such as Lespedeza sericea can prove to be extremely tough to eradicate.
Proper planning and design are important to the success of a seeded landscape, but a well thought out maintenance plan is crucial. Seeded landscapes require regular maintenance for at least 3 years to become well-established. This maintenance can include several methods such as spot-spraying of herbicides, hand-pulling of weeds, controlled burns, and mowing. I know what you’re thinking, “What? Why would you mow a seeded prairie landscape??” Mowing helps to control weeds and invasives while a seeded landscape is being established. Strategic mowing can help to strengthen root systems in the plants that you want in your seeded landscape. On challenging sites where weeds are persistent, regular maintenance can take several years before the desirable plants start to out-perform the undesirables. Once established, maintenance for native prairie landscapes becomes much less intense, and can be reduced to 1 or 2 visits per year.
When compared to the costly maintenance of a typical turf mowing schedule (26 times per year), prairie landscapes can drastically save in maintenance costs once established. More and more property owners are seeing these benefits and installing their own seeded areas to cut budgets. The benefits of seeded landscapes go well beyond cost savings. Returning your property back to its natural state provides wildlife habitat, pollinator plants, and some of the most intense root systems on Earth that percolate rainwater and stormwater runoff deep into the ground to recharge our aquifers.
Figure 1 A successful seeded prairie landscape, 2016, Photo by Fossil Photography. Figure 2 DG2 team members touring a residence with a native seed landscape, 2016, Photo by DG2 Design