Herb Robert Control – How To Get Rid Of Herb Robert Geranium Plants

Herb Robert [Geranium robertianum]
Image by Chalkdell

By Bonnie L. Grant

Herb Robert (Geranium robertianum) has an even more colorful name, Stinky Bob. What is Herb Robert? It is an attractive herb that was once sold in nurseries as an ornamental plant and used as a medicinal in simpler times. However, Herb Robert geranium is now a Class B noxious herb in Washington and Oregon. It has the ability to spread and take over native habitat quickly and prolifically. Fortunately, Herb Robert control is easy and non-toxic, although a bit tedious and time consuming. This article goes over Herb Robert identification so you can stop the spread of this potentially damaging plant.

What is Herb Robert?

Invasive weeds form a common battlefield for the gardener. Herb Robert is in the geranium family and produces the characteristic crane-shaped seed pod that all members of the family bear. The seeds eject forcefully from the pod and can travel up to 20 feet away from the plant, making it a virtual nuisance. The seeds are not the only problem because Herb Robert growing conditions are flexible such that the weed is adaptable to most soil and site conditions.

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It is unclear as to whether Herb Robert geranium is native to North America or if it was delivered here by settlers and colonizers. Either way, the plant is now widely spread across the Northwest and B.C. but present only lightly down into California. The rapid spread and ease of establishment are a threat to the local flora.

Sticky fibers on the seeds attach to animals, people and machinery to travel and establish in new regions. It was once used to treat toothaches and fever, but those beneficial traits have been buried by the explosion of plants in certain regions.

Herb Robert Identification

The weed is actually quite pretty with lacy, deeply defined leaves and pleasant 5-petaled pink flowers. The flower becomes a beak-like pod filled with many tiny black seeds. It grows low to the ground and may be found hiding under desired plants. In forests, it forms dense mats of interlocking leaves and rosette plants. The leaves and stems are covered with sticky hairs that give off a strange smell, leading to the name Stinky Bob.

Herb Robert Control

Forests, ditches, disturbed soil, garden beds, low mountain terrain and almost any other location provide ideal Herb Robert growing conditions. It prefers well-drained soil but can survive in slightly boggy areas as well. The weed has a very short and branching root system. This means hand pulling is easy and effective.

You can also mow the plants if you can get to them before they flower and seed. It is best to send the weeds to the county composting facility, as most home compost units do not get hot enough to kill seeds. Use organic mulch to control any seedlings and prevent germination.

Herb Robert geranium may look innocent enough, but it has the ability to get out of control and populate areas of commercial and native vegetation. Close your eyes to its sweet fern-like leaves and pink to white delicate flowers and pull.

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