Pot Up Your Natives

from Perennials
Sometimes the best plants for a window box or patio pot are the ones just beyond your backyard. See how one horticulturalist has created container gardening combinations with native plants.

Two years ago, Pam Thomas decided to extend the definition of a native plant garden. A horticulturist at the New England Wild Flower Society’s premier Garden in the Woods in Framingham, Massachusetts, Thomas knew only too well that most people think of native plants in terms of vistas of golds and purples waving in sunny summer meadows or swaths of pinks and blues streaming through spring woodland floors.

Such thinking left decks, patios, and enclosed spaces bereft of the beauty and easy-care nature of native plants. In particular, it meant that the courtyard at the society’s education center was rather bare and unattractive. Thomas’s solution was to create groupings of pots filled with natives.

“I was fortunate in that I had such a wide choice of plants available,” she says, “because the society’s nursery grows thousands to sell. I decided to emphasize plants with spring flowers and foliage interest throughout the growing season.”

In many ways, the design aspects of creating a container garden are similar to those in planting a border. Foliage color, texture, and shape are crucial factors, as is plant height. “One thing to remember,” Thomas says, “is to be wary of plants that go dormant or get tired as summer progresses.”

Bloodroots (Sanguinaria canadensis), for example, have exquisite white flowers in spring and handsome scalloped leaves into early summer. By August, however, these perennials start to wane and take away from the loveliness of a container planting. (Once the nights start getting colder, gather your potted perennials in an area protected from the harshest winds. Cover the pots with a generous amount of mulch; weigh the mulch down. Make sure the soil in the pots is moist to allow for the best freezing.)

You also need to consider the size of the container and the size of the plants you want to include. Small containers, for example, are not suitable for large, blowsy plants, and diminutive plants often are swallowed up in large pots.

“The native plant container garden has more than met our expectations,” Thomas says. “It has stimulated student and customer interest in lesser-known plants. It has also allowed me to experiment with new plants and new combinations every year. It’s been fun.”

Select an area, noting its light patterns. If possible, try to factor in the change in light as trees leaf out in spring and the sun gets higher during summer. In this case, New England Wild Flower Society horticulturist Pam Thomas chose a lightly shaded setting. She selected a variety of plants for their flower and foliage color as well as their height. To accommodate multiple plants, she decided on one large pot rather than a combination of smaller pots. She filled the pot to within 1 inch of its lip with a well-draining potting soil mix.

Thomas sited the plants in the container, moving them around to make sure the combination was pleasing from all angles. Once she was satisfied with the placement, she dug depressions in the mix and gently placed the plants in their allotted spaces, lightly firming them in. (If you incorporate plants dug from your garden, remove as much soil as possible from their roots because garden soil is heavier than a potting mix and does not allow for the aeration and drainage that roots need to flourish in a container.)

The finished display features the smoky purple leaves of ‘Chocolate’, a white snakeroot (Eupatorium rugosum) cultivar; the powdery, almost blue leaves of ‘Woodlander’s Blue’, a cultivar of dusty Zenobia pulverulenta; and the white-and-green variegated foliage of ‘Stairway to Heaven’, a New England Wild Flower Society patented introduction of Jacob’s ladder (Polemonium reptans). Thomas applies a diluted 20–20–20 liquid feed once a month and waters as necessary; weeding the tightly packed grouping is unnecessary.