Following nature in landscape design
Darrel Morrison sums up the designing of natural landscapes in a few words such as diversity, richness, location appropriate and dynamism.
Since the 1960s, Morrison has designed numerous venues in the eastern half of the United States, including the native plants garden at the University of Wisconsin's Arboretum in Madison. After recently becoming a Madison resident, he was the keynote speaker at the 20th anniversary 'Toward Harmony with Nature' conference sponsored by the 257-member Fox Valley chapter of Wild Ones.
Morrison's presentation was titled 'Rivers and Drifts: Natural Processes and Patterns in Designed Places.' He credited his career-long emphasis on relying on native plants, native plant communities, and natural processes to his 1960s discovery of the book 'American Plants for American Gardens' that was written in 1929 by Edith Roberts. It is now out of print.
Among Morrison's projects are the botanical gardens in New York City and Brooklyn (only 150 feet from Flatbush Avenue), the Lady Bird Johnson Wildflower in Austin, TX., a prairie restoration near Augusta, GA., projects in New York's Westchester County (an area of only 10 by 20 feet with sun and shade) and West Village at New York University, and a hillside of trees and grass in Wisconsin's Iowa County. His current project is at the Stella Niagara Preserve in western New York state.
Rivers and drifts
Morrison has employed the 'rivers and drifts' imagery, which suggests flowing, throughout his landscape designs. It applies to color, texture and visual effects such as lighting, shadows and openness, he explained.
The overall effect ought to convey mystery and a balance of complexity and coherence, Morrison stated. He calls that 'legibility.'
Before selecting any particular native species, it is essential to recognize the relationship between the potential biomass of the plants and the amount of space, Morrison explained. That will allow the design to portray a direction of flow as the plants are placed — either by seeding or plugs, he pointed out.
Another fundamental in Morrison's approach is to work with plants that are 'of the place' not only because they grow well there but also to protect the regional differences in the placement of native plants and their communities. He pointed out that the one eighth of an acre New York West Village restoration project has only plants known to have grown there at the original settlement in 1609. It draws up to 10,000 visitors per day.
On New York's Long Island, the original expanse of about 40,000 acres of native grasses, which contained 5 distinct plant communities, has been reduced to only 38 acres, Morrison observed. On a related point, he praised New York City's parks department for propagating 150 species (150,000 plants) in a restoration project.
For the Madison Arboretum project that was conducted from 1997 to 2002, Morrison chose species from 11 plant communities that are native to southwest Wisconsin. He noted that this involved three levels of progression — replacing the existing vegetation with native plants, adding diversity with ground layer species, and introducing seasonal changes for visual effect.
Morrison recommends the book 'The Vegetation of Wisconsin' by John Curtis as a guide for projects within the state. He noted that Curtis described 22 plant communities in the state.
Unlike some other landscapers, Morrison advocates allowing native plants to expand their territory but does not hold the same view on invasive species. 'Allow nature to evolve,' he advised. 'There's too much mowing and clipping to keep native plants in the same place.'
Morrison is also a strong advocate for periodic burning of prairie grass debris, calling it 'an excellent management tool.' He showed examples of vigorous regrowth only a few weeks after a controlled early spring burn.
For controlling annual weeds, 'don't pull them,' Morrison stressed. He advises cutting them several times to thwart reproduction. Pulling those weeds often serves to disturb the soil and activate the growth of other undesirable plants, he explained.
To a question about why he doesn't include native plants which are edible for humans in his designs, Morrison replied that he is confident that natural processes will introduce them over time. He is also confident that a diversity of native plants will snuff out any invasive plants trying to gain a foothold on the landscape.