“Plant experiences,” whether in the wild or in gardens, are linked to human health in profound ways.  Many studies have shown that exposure to urban greenspace lowers risk of mental illness, increases physical activity, and promotes overall wellbeing. At the same time, the rapid growth of urban areas in Colorado mean that this natural connection (most commonly made in urban greenspace by city dwellers) is at risk.  Furthermore, outdated landscape practices tax our limited resources, especially water.  CSU Extension in Douglas County has launched a project to investigate a regionally appropriate technique for the installation and maintenance of high-functioning urban green space without the need for intensive inputs. 

Our aim is to develop suites of plants that provide: 1) stable ecological community with long, heavy blooming season); 2) complete coverage of plants; and 3) less maintenance than turfgrass, the current “inexpensive, low-maintenance” landscape standard. Researchers at the University of Sheffield (UK) demonstrated the feasibility of seeding to install flower-rich, low-maintenance landscapes that elicit strong physical and mental health responses.  These projects, though, were in climates with regular precipitation; practices leading to success in a seasonally dry climate like Colorado are less known.

Two “seeded meadow” gardens have been installed at Denver Botanic Gardens since 2017; those projects have demonstrated the need for modifying the “Sheffield approach” for success, particularly in sowing medium and species selection for good performance under truly xeric conditions in the West.  CSU Extension in Douglas County installed a pilot research plot in fall 2020. We are testing drought-tolerant plant species mixes for ease of establishment from seed and community stability over time, and public perceptions of these meadows.

Several test sites across the state have been identified and installed, including publicly accessible meadows at the county Extension office in Castle Rock, Depot Park in Englewood, CO. Data are being collected about community composition and stability over time; the first medium-term data about flowering and plant community stability will be available in late 2025.

Growing flowering meadows from seed was pioneered and championed by the University of Sheffield in the United Kingdom. While the plant communities anticipated to be successful in Colorado are quite different than those used in rainier places, the installation principles remain the same. They include:

1. Evaluate the site. Knowing the soil’s water holding capacity and nutrient levels inform the choice of plant species.
2. Suppress the seed bank. Many sites, even if well maintained, have a large reservoir of un-germinated weed seeds. By spreading a layer of “sowing mulch,” a weed-free substrate that will support plant growth, one can promote the development of the designed plant community from seed with less interference from other plants.
3. Installation. Once the site has been cleared of existing vegetation, sowing mulch installed, and seeds sown, careful observation for the desired seedlings and any weed seedlings that may have blown in is required. Early weed management is key to success; one of our test sites was overrun by Kochia, a common western weed, in a matter of weeks.
4. Water. During the establishment phase of seedlings, watering is needed. Western perennials in the wild are recruited only in the ideal years, when temperatures and precipitation are supportive of establishment and growth of seedlings. (For this reason, long-lived plants in naturally dry habitats can often be readily grouped into age cohorts, based on “good years.”) For a landscape installer, watering the newly sown area for the first several weeks after germination helps create a “good year” for your meadow, even if the weather is less than cooperative.
5. Maintenance. Keep a close eye and remove any weeds before the desirable plants are able to close canopy and shade out weed seedlings. This could be a year or more. Depending on aesthetic or other considerations, cut the meadow back up to once a year, when plants are dormant.