Ragweed
Ambrosia artemisiifolia
A common annual weed that produces large amounts of lightweight, wind-blown pollen in late summer and fall. It has fern-like, deeply divided leaves and inconspicuous greenish flower spikes.
- Light
- Full sun
- Water
- Drought-tolerant
- Difficulty
- Easy
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Overview
Common ragweed (Ambrosia artemisiifolia) is an annual weed in the aster family (Asteraceae) and one of the most prolific pollen producers in North America. A single plant can release a billion pollen grains in a season.
It germinates in spring, grows through summer, and flowers in late summer and fall. Its lightweight pollen travels for miles on the wind. Though plain-looking, it is ecologically significant and a familiar sight on disturbed ground.
How to identify it
Recognize ragweed by its finely divided, fern-like foliage and greenish flower spikes.
- Erect annual, usually 1-4 ft tall (occasionally taller)
- Deeply lobed, almost fern-like leaves, green on top and often grayish-hairy beneath
- Hairy, branching stems
- Tiny greenish-yellow male flowers in slender, nodding terminal spikes; inconspicuous female flowers below
- No showy petals; easy to overlook until pollen season
Care & growing
Ragweed is a weed usually managed for removal.
- Light: Full sun
- Water: Drought-tolerant; thrives on neglect
- Soil: Tolerates poor, dry, disturbed soils
- Temperature: Warm-season annual killed by frost after seeding
- Propagation: By abundant, long-lived seed (can persist decades in soil)
- Control: Pull or mow before flowering in late summer to prevent pollen and seed; persistent infestations may need repeated removal or herbicides
Habitat & origin
Common ragweed is native to North America and has become an invasive weed in Europe, Asia and elsewhere.
It colonizes disturbed ground: roadsides, fields, vacant lots, construction sites, riverbanks and crop margins. It favors open, sunny, disturbed soils and is especially abundant in agricultural regions.
Frequently asked questions
Is ragweed the same as goldenrod?
No. Goldenrod has showy yellow flowers and insect-carried pollen, while ragweed has plain green flowers and lightweight wind-blown pollen. The two are often confused because they bloom at the same time of year.
How do I get rid of ragweed?
Pull or mow it before it flowers in late summer to stop pollen and seed production. For large stands, repeated mowing or herbicides may be needed, and removing plants for several years helps deplete the seed bank.
How tall does ragweed grow?
Common ragweed is usually 1-4 ft tall, though in rich, open ground it can occasionally grow taller, with hairy, branching stems.
Where does ragweed typically grow?
It colonizes disturbed, sunny ground such as roadsides, fields, vacant lots, riverbanks, and crop margins, and is especially common in agricultural regions.
Ragweed guides
In-depth guides for identifying, growing, and caring for Ragweed.
Ragweed identified by the community
Real specimens identified with Plant Identifier.
