My somewhat cranky post on Peach-leaf Bellflower has to be one of the most visited in this blog’s archive. It seems a lot of gardeners are interested in bellflowers. Because that post was a diatribe against Campanula persicifolia, I thought I would take a more temperate look at them now, when their first flush of bloom is nearly over.
The genus Campanula, or bellflowers, is huge — more than 500 species. It includes perennials, biennials and annuals ranging from a few inches high to six feet, but most seem to be in the one to three foot range. They occur in a variety of temperate habitats, including woodlands, grasslands, alpine and arctic regions. Dozens of species have found their way into gardens and have attracted the attention of plant breeders, resulting in many horticultural varieties.
I personally have experience with only a few of the bellflowers. Only two, actually. I recall the biennial Canterbury bells called “Cup and Saucer” from childhood, but have never grown it myself. Someone once gave me a plant of a creeping type, possibly a cultivar of C. carpatica, but it did not last. The two that have, and will probably be here forever, are C. persicifolia, Peach-leaf Bellflower, and C. rapunculoides, whose common name — Creeping Bellflower — should give any gardener the creeps. The authors of Perennials for American Gardens warn that “it must never be introduced into gardens, except into the wildest areas.” Well, it somehow got introduced into my garden, although not by me. At present, there is a clump growing out of asphalt on the edge of the driveway and another at the base of a Norway maple. The latter appears to be spreading slowly. Every spring I dig up the outermost sprouts, but I suspect it’s gaining ground. I also see it over the fence near my shed, and have conducted a little herbicidal warfare to keep it out.
The interesting thing is that the rapacious C. rapunculoides is quite attractive — more so than C. persicifolia, whose flowers are wide open, outward facing cups, while those of the former are downward-facing in the true bell-like manner, with elegant pointed edges.
On my way to work by bicycle I admire a nice clump of this plant growing at the foot of a bus stop sign, in the crack between sidewalk and curb. It’s obviously never watered except by rain (nonexistent at this time of year) or cared for in any way, but puts on a show every summer.
But — and it’s a big “but” — these two bellflowers are inveterate spreaders. Rapunculoides spreads mostly by underground rhizomes, forming fat tuberous storage roots. Every bit of root is capable of forming a new plant, so careful digging and disposal (not in the compost heap) is needed to remove it. Mostly it’s impossible to get rid of it entirely which is why it needs to be watched carefully and extracted as much as possible every spring.
Peach-leaf bellflower distributes itself both by seeds and underground roots, but is generally a bit easier to remove, except when it becomes entrenched among other desirable plants, when digging it up means digging up the entire bed. Careful deadheading can prevent excessive seeding, but the more plants you have the harder it is to keep up with the spent flowers about to become seedheads. The purest deadheading technique is to snip each flower individually, allowing the new buds forming lower on the stem to develop. This is fine if you have only a few easily accessible plants, and more time and patience than I have. Cutting entire flowering stems once most of the blooms are over works quite well. My plants manage to rebloom once or twice after this treatment.
So do I still think of Peach-leaf Bellflower as a “garden enemy?” Not really, but I suggest that gardeners think carefully before introducing it, especially to neat and tidy gardens. It’s actually one of the tough plants that are valuable in adverse conditions (such as dry shade), but become a little too pushy in favourable ones. In such situations, I would advise a gardener who wants to try campanulas to visit a good garden centre and obtain some of the horticultural named varieties, which tend to be less aggressive.
And for those who already have these two bellflowers, all I can say is that they create an opportunity for the gardener to exercise some mental discipline. Fight or negotiate? Attack or maintain a watchful peace? Who says gardening is a genteel pastime?