Landscape designer Larry Weaner admires a plot of Black-eyed Susans at the Royal Botanic Gardens in Kew, London, where he designed an American prairie. (Photo courtesy Jim Holden)
When it comes to native plants, Landscape designer Larry Weaner says “break the rules” and plant wide swaths beyond the scale of an isolated garden bed.
Weaner has spent a lifetime observing how plants grow and proliferate in nature, starting as a child studying wild vegetation along the railroad tracks behind his Philadelphia home.
His landscape design, installation and management firm, Larry Weaner Landscape Associates in Montgomery County, Pa., is renowned for an innovative blend of ecological restoration and native garden design.
One of his projects is a 3-acre American Prairie at Wakehurst, part of the Royal Botanic Gardens in Kew, London.
Going beyond the “right plant, right place” philosophy, Weaner said gardeners should match the plant to the soil, not vice versa.
“If you take the soil and make it best for a wide variety of plants, then the variety of weeds grows, too,” he said during an address at the Delaware Horticulture Industry Expo in January. “Instead, choose plants that naturally grow in those conditions.”
He warned that plowing homogenized soil is not helpful to plants that prefer their original soil condition, also encourages weed growth.
Some plants are “conservatives,” which Weaner described as having a narrow window of conditions where they thrive. The Philadelphia lily (Lilium philadelphicum), or wood lily, is very conservative.
It grows in dry, edgy soil with a high pH. It is typically only found in relatively undisturbed natural areas.
Coreopsis rosea, or pink tickseed, grows along the fringe of a pond.
It has very little drought tolerance and needs consistently moist soils in order to thrive.
Weaner suggested mimicking the natural spacing and arrangement of plant communities — duplicate how things grow in nature, in a layered landscape.
“Nature has worked it out,” he said.
Note what plants have co-evolved together.
Grow them together and you’ll have less maintenance to do.
A dense ground layer suppresses weeds. Mulch is needed only in the beginning, upon initial planting.
He recommended cutting back the ground layer only in spring, not fall.
He also urged against the removal of fallen wood. Leaving it recycles nutrients, he said.
“Lay it flat if it’s unsightly,” he said.
Understory trees also are a part of nature.
The fibrous roots of dogwood grow well in proximity to a hickory with a long taproot.
When plants are happy, they will take over a space, suppress weeds and may even become “garden thugs.”
Rather than going to great effort and expense to place every plant in a designed landscape, let the thugs spread!
One example is hairy skullcap, Scutellaria elliptica, a wildflower in the mint family that is a prolific seeder.
It needs well-drained soils and doesn’t tolerate standing water.
Use this plant in a part shade or woodland garden in small groupings, in the border or on a slope.
Weaner recommended installing more plants in smaller sizes rather than just a few larger specimens.
Even with larger plants, especially those with tap roots, the shape of the pot should match the root system.
“Ask for what you want (at a nursery or garden center),” he said.
He told the landscapers it is important to communicate to their customers that planting wide swaths of natives does not mean low maintenance at the beginning.
“Nothing is no maintenance!” he said, adding, “A plant in a pot is on life support. Once planted, it needs a lot of care.”
After a plant is established, however, it should be watered only when it needs water.
And, it is important to let the plant grow its root system first.
Weaner’s altered planting protocol — more plants in less space — results in a dense ground level layer that helps suppress weeds.
Where you have this thick layer of plants, he suggested cutting weeds rather than pulling them so as not to disturb the soil, since disturbance leads to weed generation.
This does not apply to the most aggressive weeds, he noted.
“If you’ve got good native plants already, just remove the weeds,” Weaner said.
