Colorado Master Gardeners: Decorative ground cover or weed
July 4, 2017
Last summer I researched a cultivated plant, a pretty ground cover that, in my garden, turned shabby and thirsty looking by August.
Snow on the mountain or bishop's weed (Aegopodium podagraria) is a nonnative ornamental plant brought by the European settlers to North America that thrives in shady areas, spreads by itself and inhibits weeds. Although CSU Extension lists it as a suitable ground cover, other garden sites have labeled it one of the "worst" garden weeds in perennial flower gardens. In a previous article, I determined it was a weed, calling it bishop's weed.
My war on bishop's weed started when I casually dug it up. Bad idea: bishop's weed spreads by underground rhizomes that generate new growth from pieces of root left in the soil. The resulting dense mat not only looked thirsty and shabby, it threatened newly planted native shrubs.
My next move — after my research — was to trim it to the ground and cover the area with cardboard and compost. Then I waited. Surely the cardboard and compost and several feet of winter snow would discourage it.
Well, not quite. In May, healthy shoots peeked out in the seams of the cardboard, next to a big rock, among other perennials, and was creeping into new areas. I cut back the new growth and added a layer of mulch. Chemical annihilation is not an option; the garden is for the pollinators. I'm now watching to see what happens next.
In the meantime, I've begun to think that bishop's weed isn't such a terrible weed after all. I've noticed beautiful beds around town, dense mats of bluish-green variegated leaves and spikes of small white flowers.
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Fellow local gardeners refer to it as snow-on-the-mountain and admit it can be invasive but responds well to barriers. It may need trimming/digging to allow room for other plants and some level of irrigation, depending on the location. In fact, in the right place — shady, contained, not too dry — it grows quite nicely all summer long and shades out unwanted grasses and weeds. It is a plant that is shared among neighbors and relatives, often associated with Grandma's garden and fond memories.
I've developed an appreciation for bishop's weed, which, after my failed eradication attempts, I now call snow on the mountain. The thought of fighting it in my garden over the next several years — a certainty when chemicals are not used — is just too daunting. It is flourishing everywhere in Steamboat – in the neighbor's garden, on Yampa Street, in front of the Tread of Pioneers Museum, at the Pine Grove Center – so there might be a place for it in my garden after all.
I must remember, though, it can be invasive, aggressive and quite unattractive over time. So, rather than strive for complete elimination, I will focus on containment, discouraging growth where it is unwanted or unsightly. Perhaps I can convince all the pretty, invasive, nonnative plants I've inherited to play nicely with the native plants I've planted to support the bees and birds and butterflies.
A long-time Steamboat resident and casual gardener, Vicky Barney is a member of the Master Gardener Class of 2011.