Q: I have a large bank covered with bishop’s weed. What can I add to make the planting more interesting? — Gary Johnson, W. Peabody, Mass.
A: Nothing. You may not realize it but you are involved with Aegopodium podagraria, one of the great thugs of the plant world. It was called gout-weed where I grew up — for its supposed medicinal properties — but it is more likely to cause gout (or worse) in the gardener who tries to remove it. This tough perennial spreads by underground rootstocks so dense and vigorous that — except for shrubs and trees — other plants don’t stand a chance. But it has a good side; it also chokes all but the most tenacious weeds. Either learn to live with it as a monotonous but easy-care bank cover or declare war on it. Smothering bishop’s weed under black plastic or subjecting it to at least a half-dozen sprayings of glyphosate every three to four weeks during the growing season are the only ways to get rid of it.