How to Identify and Avoid Ragweed

Ragweed looks like a fairly nondescript weed, usually with fernlike or larger green leaves. It's a plant many people know by name because it's a prime source of fall allergies in North America.1 It starts blooming in the late summer, usually in August, and goes through till November, with the highest pollen month being September.

Read on to learn more about ragweed and how to identify the two types by their leaves and flowers.

Fast Facts

• Common ragweed's scientific name is Ambrosia artemisiifolia and giant ragweed's scientific name is Ambrosia trifida. Common ragweed often is easily confused with some other plants, such as mugwort,

• Ragweed is part of the Asteraceae family.

• Ragweed grows tall and has nondescript flowers and ragged or palm-shaped foliage.

• Ragweed seeds are beneficial wildlife food.

• Ragweed has the life cycle of an annual summer weed.

Types of Ragweed

There are two main types of ragweed: common ragweed and giant ragweed. Common ragweed grows to 6 feet tall with a fernlike appearance. Giant ragweed grows to a staggering 15 feet tall with leaves shaped like the palms of hands. Both types of ragweed have other identifying characteristics.

Common Ragweed Leaves

The leaf of the common ragweed plant has a fern-like appearance. Young leaves typically have some purple speckling on them. However, other weeds, such as lamb's quarters, can also have purple markings.

Common Ragweed Blooms

The Ambrosia genus of which ragweed is a part belongs to the aster family but common ragweed blooms, which appear as small, yellowish bumps, are exceedingly inconspicuous. The flowers are followed by unremarkable brownish fruits.

Giant Ragweed Leaves

Giant ragweed bears leaves that resemble the shape of a palm of a hand. The leaves usually have serrated edges, and their green stems are covered in tiny white hairs. Plus, the smaller leaves around the base of the plant often have hairs on their undersides. Overall, the leaves can be up to a foot long and 8 inches across.

Giant Ragweed Blooms

Giant ragweed flowers are similar to common ragweed flowers. Many of the upper stems of the plant grow a flower spike that is cylindrical and roughly 3 to 6 inches long. The plant also will often have slightly smaller flower spikes closer to its base. Like common ragweed, the blooms appear like small bumps. The flowers start green but turn yellow-green and then yellow-brown color as they mature.

How to Control Ragweed

Keep ragweed from taking over your yard by fertilizing, mowing regularly, keeping the flower beds maintained, and clearing out the weeds. Control ragweed already in your yard by pulling it out by hand. This method may be effective if it's done before the ragweed blooms, or else new seeds will scatter around in your yard and garden beds.

If you prefer a chemical solution, use a weed-killer herbicide, which should be applied during the midspring to early summertime while the plants are still immature.

FAQ

• How do you know if you have a ragweed allergy?

  You know if you have a ragweed allergy if you have a stuffy, runny nose, postnasal drip, sneezing, itchy and swollen nose, eyes, ears, and mouth, watery and red eyes in the late summer into fall. You may be coughing and have shortness of breath, as well. You're not alone. Approximately 5 million people in the United States suffer from ragweed pollen allergies yearly.

• Why are so many people allergic to ragweed?

  Many people are allergic to ragweed because one plant produces 1 billion pollen grains that float around in the environment and cause havoc with our immune systems.

• What is another name for ragweed?

  Another name for ragweed is ambrosia.

• Is there a cure for ragweed allergies?

  There is no cure for ragweed allergies. Manage ragweed allergies by knowing when pollen counts are high in your area, staying indoors with closed windows and doors, and taking allergy medicines before the season starts.