Ragweed is a summer annual noxious weed in the daisy family (Asteraceae) and is native to most of North America but has naturalized in many parts of the world. The Genus name is Greek for "food of the gods" or "drink of immortality." The species name refers to the leaves resembling the leaves of wormwoods. This plant is adaptive to various soils and prefers drier conditions in full sun to partial shade. It generally grows 1 to 3 feet tall but can reach heights of 6 feet with a 3 to 4-foot spread. It is drought and poor soil tolerant This is the culprit for causing allergies, hay fever, and contact dermatitis. The male flowers release copious amounts of pollen in late summer to fall, which is dispersed by the wind. Many seeds are produced that remain viable for several years. Birds and game birds love the seeds due to the high oil content. The leaves are deeply lobed giving it a fern-like look and the flowers are non-showy in terminal spike-like clusters. Control is best accomplished by hoeing and hand pulling. There are now glyphosate-resistant strains in the United States. Insects, Diseases, and Other Plant Problems: The ragweed leaf beetle was found to be an effective control in Europe and is being released to other countries.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day)
Soil texture
Clay; Sand; Shallow Rocky
Soil drainage
Good Drainage | Occasionally Dry | Very Dry
Mature size
Height: 1 ft. 0 in. - 6 ft. 0 in. | Width: 3 ft. 0 in. - 4 ft. 0 in.
Growth rate
Rapid
Maintenance
High
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Erect; Multi-stemmed
Texture
Fine
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Alternate; Opposite
Leaf shape
Lanceolate; Pinnatifid
Leaf margin
Lobed
Leaf size
3-6 inches long, 1-3 inches wide
Hairs present
Yes
Leaf detail
Green leaves are up to 6 inches long and 4 inches wide. They can be alternate or opposite along the stem and have a delicate appearance, deeply lobed with the base being much wider than the tip. Young leaves will have hairs on the undersides.
Flower color
Brown/Copper; Gold/Yellow; Green
Flower form
Raceme
Flower size
< 1 inch
Flower detail
Monoecious, male flowers in 1-4 inch long terminal racemes occur and may have 2 short side spikes. Female flowers are in axillary clusters below the male. The individual 1/8 inch flower is green, turns yellow-green then brown as it matures. Pollen is released late summer into fall and is carried by the wind.
Bloom time
Fall; Summer
Fruit color
Brown/Copper
Fruit type
Achene
Fruit detail
Woody achene with 4-7 spine-like projections, resembling a crown. They contain numerous seeds that are viable for up to 5 years.
Stem color
Pink; Red/Burgundy
Stem detail
Pinkish red grooved stems are hairy.
Wildlife & Ecology
Native status
Native
Origin
North America
Distribution
AL , AR , AZ , CA , CO , CT , DC , DE , FL , GA , IA , ID , IL , IN , KS , KY , LA , MA , MD , ME , MI , MN , MO , MS , MT , NC , ND , NE , NH , NJ , NM , NV , NY , OH , OK , OR , PA , RI , SC , SD , TN , TX , UT , VA , VT , WA , WI , WV , WY Canada: AB , BC , MB , NB , NL , NS , NT , ON , PE , QC , SK