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Herb Robert. Photo Credit: Rob Routledge, Sault College, Bugwood.org -
Herb Robert flowers. Photo Credit: Rob Routledge, Sault College, Bugwood.org -
Herb Robert leaves. Photo Credit: Rob Routledge, Sault College, Bugwood.org
Also known as: stinky Bob, Robert geranium, fox geranium, red Robin, crow’s foot
Herb Robert is a low growing winter and spring annual or biannual. It spreads quickly, pushing out native plants and poses a threat to forest biodiversityBiodiversity The variety of species present.. Its leaves produce a pungent odor of diesel and mint when crushed. In recent years, it has become one of the most common woodland weeds in Western Oregon.
For a more detailed description, download the Herb Robert Best Management Practices factsheet.
Description:
| Life Cycle: | Annual (life cycle lasts one year) or Biennial (life cycle lasts two years) |
| Early Detection and Rapid Response species: | No |
| Height: | 1 foot (30 centimeters) |
| Leaf Description: | Its light green leaves are deeply dissected and covered by tiny hairs. The foliage turns red in the late fall. The leaves release a strong odor when crushed, thus giving this species the common name, ‘stinky Bob’. |
| Fruit & Flower Description: | Small, delicate flowers have five white or pink petals. It blooms throughout the spring and fall. It reproduces by seeds which may be ejected as far as 20 feet (6 meters) from the mother plant! |
| Bloom Time: | Spring through Fall |
How it spreads:
- Herb Robert spreads entirely through seeds. Once the mature seed capsule has dried it ejects the seeds as far as 20 feet (6 meters) away.
- Each capsule contains five seeds which have a sticky thread-like appendage that allows it to cling to animals, people, or vehicles.
- Flowing water and contaminated soil moved to new areas can also spread Herb Robert. Seeds can stay viable in soil for at least 6 years.
Habitat:
- Herb Robert is highly adaptable and is commonly found in moist, semi-shaded forests. It is also becoming a significant garden weed in many urban and suburban areas.
- Often it takes advantage of habitats that have been recently cleared.
Impact:
- Herb Robert can quickly spread throughout forested areas forming dense mats pushing out native flora.
- It spreads by its seeds being dispersed by water, wildlife, and humans. Its seeds can survive in the soil for several years.
- It can encroach on parks and gardens which increases landscape maintenance costs.
What you can do about it:
- Cultural: Sheet mulching is a good option for controlling smaller infestations.
- Manual: Luckily, herb Robert is an easy species to control. It has a shallow root system which makes hand pulling easy. Its best to pull plants before they produce seeds.
- Mowing or cutting it back with a string trimmer early in the season before it produces flowers is also effective.
Look-alikes:
Pacific bleeding heart (Dicentra formosa) is often confused with herb Robert and often grows in similar habitats. Pacific bleeding heart is native to the Pacific Northwest and attracts many pollinator species. It does not produce an odor when its leaves are crushed.
Shiny geranium (Geranium lucidum), another weed, is often found with herb Robert. Shiny geranium has similar leaves and flowers, but its stems have a distinctive red color.
Noxious Weed Listing:
| State of Oregon: | Class B |
| State of Washington: | Class B |
More Resources:
- Pacific Northwest Weed Management Handbook: Herb robert
- University of California, Weed Research & Information Center: Herb-robert