Lesser-known natives can do well here
By Rachel Foster
Flip through Native Plants for North American Gardens by Allan Armitage, and two things quickly become obvious. One, Northwest natives are not very well represented in this book. Two, a surprising number of the border plants we traditionally grow in gardens are native to some part of North America. Aster, coreopsis, phlox, penstemon, echinacea, rudbeckia, tall lobelia, liatris all originate in North America, most of them in the prairies and meadows of Eastern North America, where rain can occur at any time of year.
Although many of these plants are moderately drought tolerant, they have not evolved with regularly dry summers. They do not need to complete their yearly growth cycle before mid-summer, as many Willamette Valley natives do. So many of them bloom in summer, even in late summer. No wonder gardeners value them. Many have been subjected to breeding programs in the U.S. and, especially, Europe, with a goal of selecting new colors and plant forms or bigger or more elaborate flowers and so on. These cultivars have their uses, but gardeners who appreciate the unique qualities and special grace of plants selected by nature herself will tend to prefer the original version.
This natural look is the best argument I can think of for seeking these plants out.
It isn’t easy to come up with a convincing argument for making a garden exclusively of American natives. If you plant things that do not naturally occur in your region, why stop at the boundaries of one continent? But some of the lesser known North American natives, in particular, make charming additions to any perennial garden, and if they originate in places where it routinely rains in the summertime, they’ll adapt well to a conventional watering regime that supports a variety of garden perennials. Here are a few of my personal favorites. All of them should look at home mixed in with Northwest natives that tolerate the same conditions.
Amsonia tabernaemontana (Eastern blue star flower)
Willow leafed amsonia (A. t. var. salicifolia) has narrow leaves, giving the plant a particularly graceful look. It grows to about 2 feet. Amsonias bloom in late spring or early summer, with flowers in a cool, pure blue. The foliage turns gold in autumn. Another species, A. hubrichtii, has even narrower leaves. According to Armitage, this has the best fall color, but it is taller and may need staking.
Gillenia trifoliata (bowman’s root)
This is one of my favorite plants. Reddish, wiry stems and pretty foliage look especially handsome as the plant emerges in the spring. A haze of airy, pinky-white flowers soon follows, hovering about the plant like so many skimpy moths. This graceful plant is a good companion to showier flowers such as lilies but is not very drought tolerant.
Helenium autumnale (dogtooth daisy)
The wild type, like taller cultivars, can grow to 4 or 5 feet in gardens. In lush conditions and without a mass of prairie grass to hold it up, it often falls over, and not in a pretty way. It is worth holding out for shorter selections of this plant (such as Wyndley Copper, 30 inches, blooming now). Varieties are available with flowers in yellow, bronze or rusty red that seem to require less water than black-eyed Susans (rudbeckia).
Thermopsis villosa (or T. caroliniana) (Carolina false lupine)
This was, for some reason, one of the first plants I put in my Midwestern garden years ago, and I’ve grown it ever since. Think of it as an early blooming, light yellow lupine. It grows to about 3 feet.
Veronicastrum virginicum (culver’s root)
As the name implies, this is related to veronica, but it is more architectural: Whorls of leaves march up tall, stately stems, the tips of which bear white, lavender or pale pink spires of little flowers in summer. Entirely self supporting in sun, and an excellent, carefree addition for the back of a border.
I have grown all these plants in Eugene for several years. They are not particular about soil and all tend to grow productively for years without division. Some may be difficult to find locally, though I purchased all of them, at various times, from retail nurseries in Eugene.
Rachel Foster of Eugene is a writer and garden consultant. She can be reached at firstname.lastname@example.org