Common Ragweed: How to Identify and Control It
Ambrosia artemisiifolia · Summer annual broadleaf
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How to identify common ragweed
- Finely divided, fern-like leaves
- Hairy stems, 1–4 ft tall
- Slender spikes of small green flowers in late summer
- Major source of hay-fever pollen in late summer
Why it shows up
A native annual of disturbed soil, roadsides and gardens, found in all of the contiguous US. Its pollen drives late-summer allergies.
Where it's a problem
- Northeast & Mid-Atlantic (zones 4–8)
- Southeast (zones 7–10)
- Midwest (zones 4–7)
- Great Plains & Texas (zones 3–9)
Control methods
1. Cultural (prevention)
- Mulch and plant disturbed areas
- Mow or cut before flowering
2. Mechanical
- Pull before flowering (wear gloves)
3. Organic options
- Mowing and mulching
4. Chemical options
Herbicide safety — always follow the label. The label is the law: use only products labeled for your site, turfgrass or crop, and follow rates, timing, weather limits and protective equipment directions exactly. Keep people and pets off treated areas as directed, and check state and local rules. Active ingredients named here are examples from extension guidance, not endorsements; availability varies by state.
- Pre-emergents labeled for the site
- Post-emergent broadleaf products on young plants; glyphosate-resistant populations exist in crop fields
When to treat common ragweed by USDA zone
| USDA zone | Typical timing (from NOAA frost-date medians) |
|---|---|
| Zone 3 | Pre-emergent around Apr 19–May 3 (2–4 weeks before the typical last frost, May 17); spot-treat or pull escapes in early summer |
| Zone 4 | Pre-emergent around Apr 12–Apr 26 (2–4 weeks before the typical last frost, May 10); spot-treat or pull escapes in early summer |
| Zone 5 | Pre-emergent around Apr 5–Apr 19 (2–4 weeks before the typical last frost, May 3); spot-treat or pull escapes in early summer |
| Zone 6 | Pre-emergent around Mar 29–Apr 12 (2–4 weeks before the typical last frost, Apr 26); spot-treat or pull escapes in early summer |
| Zone 7 | Pre-emergent around Mar 14–Mar 28 (2–4 weeks before the typical last frost, Apr 11); spot-treat or pull escapes in early summer |
| Zone 8 | Pre-emergent around Feb 24–Mar 10 (2–4 weeks before the typical last frost, Mar 24); spot-treat or pull escapes in early summer |
| Zone 9 | Pre-emergent around Jan 26–Feb 9 (2–4 weeks before the typical last frost, Feb 23); spot-treat or pull escapes in early summer |
Zones 10–11 (frost rare): follow germination flushes after rains; pre-emergents in late summer/fall for winter weeds and late winter for summer weeds. Find your exact frost dates with the ZIP planner. Soil temperature and the product label take priority over the calendar.
Frequently asked questions
How do I get rid of common ragweed naturally?
Start with cultural and mechanical controls: Mulch and plant disturbed areas; Mow or cut before flowering; Pull before flowering (wear gloves).
What does common ragweed look like?
Finely divided, fern-like leaves; Hairy stems, 1–4 ft tall; Slender spikes of small green flowers in late summer; Major source of hay-fever pollen in late summer.
When is the best time to treat common ragweed?
Prevent it with a pre-emergent applied 2–4 weeks before your average last spring frost, when soil reaches about 55°F.
Where is common ragweed a problem in the US?
Common Ragweed is common in: Northeast & Mid-Atlantic, Southeast, Midwest, Great Plains & Texas.
Sources & further reading
- NC State Extension Gardener Plant Toolbox: Ambrosia artemisiifolia
- Ganie et al. (2017). Glyphosate-Resistant Common Ragweed (Ambrosia artemisiifolia) in Nebraska: Confirmation and Response to Postemergence Corn and Soybean Herbicides. Weed Technology. doi:10.1017/wet.2016.26
- Herbicide examples are typical active ingredients named in university extension guides; products and registrations vary by state. See your state Cooperative Extension weed-control guide.
Related weeds in the same regions
Crabgrass · Dandelion · White Clover · Field Bindweed · Yellow Nutsedge · Common Chickweed · Broadleaf Plantain · Creeping Charlie (Ground Ivy) · All 27 weeds
Planning a garden? See planting calendars by state & zone.