One of our common garden and woodland weeds here in the Pacific Northwest is a cute little geranium known variously as stinky Bob, herb Robert, red robin, death come quickly, storksbill, fox geranium, or Geranium robertianum. I usually call it herb Robert, but I hear a lot of people around here calling it stinky Bob because of the strong fragrance of the foliage. Whatever you call it, this is an introduced invasive thug — an unwelcome weed in my garden and woods.
It’s a pretty little thing, with its delicate pink flowers held above the deeply divided foliage. That’s why this plant was originally introduced to North America from Europe as a garden plant. Then it escaped.
Herb Robert is easy to recognize. The leaves are roughly triangular, palmately divided into three leaflets, all with rounded lobes. The stems are somewhat sticky and all parts of the plant are covered in coarse hairs. It’s an annual, but plants that develop in the fall will overwinter and grow big early in the spring. Some people confuse stinky Bob foliage with that of our native Pacific bleeding heart, but the leaves of the geranium are much more triangular and hairy than the softer and hairless foliage of the bleeding heart.
Stinky Bob can spread rampantly. In this photo it’s carpeting the ground below snowberries at the edge of our moss garden. Now that I’ve photographed it here, this patch is on my list of areas to weed “real soon now” before it blooms and sets seeds.
Besides spreading rampantly, one of the nasty things about Geranium robertianum is that it is at least somewhat allelopathic, meaning in the simplest terms that the plant exudes chemicals that inhibit the growth of other plants.
Fortunately, stinky Bob is relatively easy to pull out. The roots are long and fibrous, up to nearly a foot long when the conditions are right. The plant in the photo was growing in the moss and forest duff in our woods. We have to pull carefully to keep from disturbing too much of the moss we like (and which protects the soil from evaporation and rain).
Controlling herb Robert is a never-ending task. We pull it, and more seeds germinate and develop into more big healthy plants.
Herb Robert is easiest to pull when the plants are young, but it can be challenging to positively identify seedlings before the leaves get to much size so I usually don’t get to it until the rosette of reddish stems and triangular leaves is much more obvious.
If it weren’t such an invasive weed this plant would make a pretty groundcover. But I’m not about to let this stuff take over. Weed on!