Dangerous Beauties

Mary Anne Michael, Certified Master Gardener 1994

In twenty years of gardening, I’ve had certain plants that were quite lovely, healthy, and  hardy.

They flourished  in my border, attracted praise from neighbors, and generously provided blooms

for my dining table. But I’ve spent  untold hours digging them out or ruthlessly spraying herbicide

on the tiniest sprout that dares reappear. Let me explain.

Read the following plant description and see what you think. Herbaceous perennial. 2’-3’ tall x 2’-3’ wide. Dark green foliage is disease free and impervious to insects; nice yellow fall color. Lovely pure white flowers bloom in summer over a long period; superb as a cut flower. Stands out in the garden due to unique bloom habit as gracefully arched racemes all face in the same direction. Withstands drought, heat, wind. Full sun or partial shade. Hardy in zones 3-8. I’ll bet you want this beauty in your garden. I have three words for you: NO, YOU DON¹T.

The description is of Lysimachia clethroides (gooseneck lysimachia) and almost everyone who has grown it shudders at the memory. For this undeniably beautiful, hardy, carefree plant is the queen of plants that takes over a garden. And it’s well nigh impossible to get rid of once it’s established. I know.

I planted gooseneck lysimachia about fourteen years ago and was enchanted with it for the first three. It was stately, eye-catching, trouble free, and wonderful in flower arrangements. But then I noticed that the original three plants had spread outside their allotted space—way outside. So I innocently dug the invading sprouts and transplanted them to another area.

While the transplanted divisions settled in nicely, I did feel a bit uneasy about the root system, which was like a tangle of pink and white spaghetti buried deep underground. It reminded me of the roots of Artemisia vulgaris (mugwort, wild chrysanthemum), which is impossible to get rid of. The next summer all the lysimachia, old and new, spread alarmingly, overwhelming everything in its wake. Established patches of perennials disappeared completely or grew weak and spindly among the erect, aggressive stems of the gooseneck. It was as if the lysimachia either smothered its neighbor's growth above ground or strangled their roots below. I decided to get rid of it, even though it was beautiful. To make a long story short, let me say that I spent several years digging and pulling, then a couple of years applying an herbicide. After a few years without a trace I thought I’d won. I was wrong. It was back this spring, so I started the battle again.

I now know that Lysimachia clethroides is famous for being invasive in good or loose soil, although most catalogs and garden centers don¹t mention this. The only place it seems to be useful is in an area of heavy clay, either alone or with other thugs such as grasses. I know someone who has planted it in such a place, and it performs very well for her.

I’ve had similar experiences with two other plants in my perennial bed. Both were excellent
aesthetically and horticulturally, both were uncontrollably invasive. And I’m still struggling to get rid of them.

There is Allium tuberosum (garlic chive, chinese chive), which blooms from late August through most of September in the Kanawha Valley. It looks like culinary chives in foliage color and growth habit---and smell---but the leaves are flat instead of round. The foliage clump is about 12” tall by 12” wide; bloom stems grow to 24” tall. As with most alliums, there are no disease or insect problems. The blooms are beautiful, pure white spheres about the size of a golf ball, and they wave gracefully in the slightest breeze but are sturdy and unspoiled by rain or heavy wind. The white flowers mature to green seedheads that add visual interest for a few weeks more. Blooms, green seedheads, and dried seed stalks are all great in arrangements. Allium tuberosum grows in sun or part shade, isn’t particularly fussy about soil, and is hardy in zones 4-8.  Gardening books advise deadheading to prevent seedlings, but unless there are only a couple of clumps--and the gardener is more responsible than I am---this is difficult since garlic chives seem to bloom in waves. Normally I’ve welcomed volunteers in my beds. However, the clumps of garlic chives multiplied in dense masses that crowded out surrounding plants. Since the seeds dispersed over a wide area, I soon realized that I had a problem.

I’ve spent the last two years trying to dig out the deep, thick clumps of roots, and I’ve made mediocre headway. It is a shame, because Allium tuberosum still makes me happy when I see its refreshing, cool balls floating in the heat of late summer and fall.

The third heartbreaker in my garden has been Campanula latifolia, commonly called great bellflower. It grows in low clumps about 2’ wide, but the flower stalks rise to 3’-5’ with small
trumpet flowers of medium purple-blue arranged down the top half of the stalk. Bloom
season is early summer. Partial shade is ideal, according to the books, but I noticed that it performed very nicely in full sun if the soil was loose and rich. Great bellflower is hardy in Zones 3 to 6, and there are no pests or diseases that bother it. Although each flower is small, the color showed up well in the back of my border, and I was glad to add a tall source of blue for that time of year. But this perennial packed a double whammy: it not only spread rampantly by a tangle of creeping roots, it also self-seeded. Soon I was trying to pull it out of stands of Siberian iris, coreopsis, and peonies without destroying the desirable plants; I’m still trying after five years. I think this fall I’ll have to surrender and dig up entire clumps of the perennials I want to save. It
will mean tediously separating the sets of roots, then replanting the desirable ones, but there
is one good side effect: I should have some leftovers to pot for the KCMGA Plant Sale. (I
promise I won’t pass along the Campanula latifolia!)

I’ve learned some lessons from my experiences with these three plants. I’ll try to do more thorough research before buying plants, no matter how beautiful they are; I’ll try to keep a closer eye on how new plants behave in my beds the first year or two; and I’ll try to discourage anyone who is tempted by these three dangerous beauties.