Design with Natives – Plant Colonies

It happened again – I remembered something discussed in one of my native plant classes and thought “Oh, that’s what they meant – now I get it!”. Of course, that’s the difference between classroom learning and applied learning, and I expect it. But maybe because I’m doing ever more hands-on work with plants and sustainable gardening, it’s happening pretty often.

The latest one came as I thought about the difference between traditional gardening and native plant gardening, specifically when laying out plants in a new garden area. I had been to Garden in the Woods in Framingham MA and had been inspired by their spring-flowering woodland section of foamflower (Tiarella cordifolia var. cordifolia) and two kinds of native phlox (Phlox diverticula and Phlox stolonifera).

Woodland Planting, Garden in the Woods, Framingham MA

Their planting was on a hillside and had to be at least 80’ long by 40’ wide. There were drifts of plants, and some half-empty spots here and there, but no obvious plant placement. It looked natural, although it was clearly a designed space.

 

My Garden, Area for New Planting

I had a roughly 6’x10’ sloped area at one end of the woodland garden that needed a new design, so I decided to try something similar. I bought about 10 plants of each kind and set about trying to place them in the design. I first tried English-style drifts of plants so the different types would contrast with each other but decided that wasn’t natural enough. I went back and studied the woodland planting a little more. And here’s where I had my “Aha!” moment.

The GITW planting was not a static design. The designers had created an intermingled plant colony. In part, this was the stylistic effect they wanted, but this approach was also required to satisfy the biology of native plants.

Traditional nursery plants tend to stay where you plant them.  Most are hybrids and are sterile, so they don’t self-seed. The nursery horticulturalists also tend to select plants that don’t aggressively spread throughout the landscape. (This is discrimination – plants that spread are labelled “thugs”!)

In contrast, native plants are genetically programmed to seek out resources to survive, including spreading across available ground space, and to create and distribute seed so the species prospers. It’s really not possible to stop these processes, so the native plant gardener is smart to create a planting strategy to take advantage of these characteristics rather than fight them.

Once I stopped thinking about designing a static garden composition and started thinking about my 30 plants being the starting point for an expanding plant colony, I made progress. To start, I looked up* how each of the plants reproduce and spread. This particular variety of Tiarella sends out runners like strawberries and expands into larger mats that fill in bare spots, eventually becoming an attractive groundcover. The Phlox both send out stolons or runners and will root at the nodes, also eventually forming large mats in the right conditions.

 

From left: Tiarella cordifolia var. cordifolia, Phlox divaricata, Phlox stolonifera

My challenge as a designer then was how to visualize what these colonies might look like in, say, 3-4 years after the plants had spread, and then to decide how to arrange these larger colonies. The Phlox divaricata was taller (12-15’), the Tiarella in the middle (8-10” flowers over 4” foliage) and the Phlox stolonifera the lowest. Because of the height differences, it seemed best to group each plant type somewhat together rather than mix them into drifts or a mosaic.

 

In the end, I decided to start my plant colonies off with a yin-yang design. The Tiarella was placed in a curved shape that divided the space in two, and each Phlox was placed on one side of the space., with the taller Phlox divaricata on the uphill side and the Phlox stolonifera below. The plants were somewhat spaced out, but not in rows or too rigid a pattern, so they have room to spread.

It will be really interesting to watch how these colonies develop over time!

 

*Sources:

missouribotanicalgarden.com>Gardens and Gardening>Plant Finder

Native Plants for New England Gardens, Mark Richardson and Dan Jaffe

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