How to Identify Common Ragweed

A common ragweed plant coming up out of the ground

The Spruce / David Beaulieu

Common ragweed (Ambrosia artemisiifolia) is unattractive as well as noxious. But the challenge in removing it is most people have trouble identifying the nondescript plant. Common ragweed is classified botanically as an annual, meaning it completes its life cycle in one growing season. Like its giant ragweed relative, Ambrosia trifida, it is considered a broadleaf weed for its flat and relatively broad leaves.

Ragweed is responsible for hay fever. But because common ragweed is rather unremarkable, goldenrod is often blamed for causing hay fever when ragweed is the real culprit. Goldenrod and common ragweed both bloom in late summer or early fall, depending on where you live. Being the more conspicuous of the two, goldenrod has become the scapegoat for hay fever while the true villain goes unnoticed.

Learn what common ragweed looks like and how to get rid of any growing in your yard.

Common Ragweed Identification

The most remarkable aspect about common ragweed's appearance is it bears an intricately toothed leaf. The weed's tan-green flower stalks are inconspicuous. They look a bit like those of common plantain (Plantago major), a common lawn weed. Common ragweed can reach 1 to 6 feet tall. But in a yard subjected to foot traffic, mowing, weed wacking, and other disruptions, it is usually found growing at the smaller end of that spectrum.

The plant is indigenous to North America. It can be found in every state in the United States except for Alaska, and it is widespread in Canada, too. The plant thrives in disturbed soils and is frequently found along roadsides.

Common Ragweed and Allergies

Together, common ragweed and giant ragweed account for most of the hay fever experienced in North America in the fall. Symptoms of hay fever are sneezing and runny nose, along with itchy eyes.

Although the name hay fever alludes to the "haying" season in the fall, people often refer to allergies experienced at any time of year as hay fever. Thus birch trees, for example, are spoken of as a major source of hay fever in eastern North America, even though the hay fever resulting from their pollen occurs in spring and not fall.

Furthermore, while it's more often associated with hay fever, common ragweed is also one of the plants that cause skin rashes (known technically as allergic contact dermatitis). You can lessen these allergy symptoms by getting rid of ragweed in your yard. But no matter how good of a job you do, its pollen might still be in the air from surrounding yards.

So what is someone with allergies to do? Stay inside all September? Try to minimize your outdoor activities when the pollen count is highest, which is generally between 10 a.m. and 4 p.m. This practice won't eliminate your hay fever, but it can lessen the severity of the symptoms.

Getting Rid of Common Ragweed

Because it spreads via seed, efforts to keep common ragweed from spreading should focus on preventing seed production. As a bonus, if eradication occurs prior to flowering, you will reduce hay fever pollens.

Hand-pulling is the best method of getting rid of common ragweed in the garden. The plants are easy to pull, as they have shallow root systems. But make sure to wear thick gardening gloves and long sleeves and pants to do your weeding to avoid triggering any skin rashes due to contact with the plant.