The old adage is "a weed is just a plant out of place," but there's often more to it. A new plant may enhance its new home by supplying nectar for bees or berries for birds. We don't call it a weed unless we discover it doing some sort of damage. Herb Robert (Geranium robertianum) is just that kind of plant. Common (and well-behaved) in the upper Midwest, this weed has taken root in the disturbed areas of Northwest forests. It can be seen along logging roads and in deeply shaded glens. Once there, it begins to crowd out native species. Its ability to scatter its seeds up to 20 feet away gives it a real advantage in the forest floor. A diversity of plants helps keep an ecosystem healthy, and this thug is upsetting the balance.
Increasingly, Herb Robert has found its way into Northwest backyard landscapes and gardens. From an ornamental point of view, it has some appeal. It comes up early in the year, when even the earliest bulbs are just poking through the mulch. Its bright green foliage has a bit of a ferny appearance, and there are pink or white flowers, as the weather warms up. But, once in the garden, it behaves just as it does in the forest: it covers the ground, crowding out everything else and re-seeding itself quickly. Gardeners trying to clear out this pest quickly find out why it gained the nickname Stinky Bob. The plant breaks off easily when pulled, leaving the root to quickly re-grow and a nasty smell on hands and gloves.
At one time, nurseries and garden centers offered Stinky Bob for sale - before its aggressive nature was discovered. Today, we can find a variety of plants, both ornamental and native, that have the same woodland look, but will not become a nuisance. The Northwest native, Woodland strawberry (Frageria vesca), has a textured leaf with a delicate white flower. Plus, the smallish fruit is considered by some to be better tasting than its commercial cousins. Or choose the more closely-related Cranesbill geranium (Geranium sanguineum). It has a very similar look to Stinky Bob, with a pink flower. Home gardeners can't do much to keep plant invaders from our shores, but ensuring that these weeds don't take root in our shrub beds and flower borders is a little something that makes a big difference.