Giant Ragweed
Ambrosia trifida
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Pl. BA69 — Ambrosia trifida
Ambrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifidaAmbrosia trifida
IOverview
Overview
Giant Ragweed (Ambrosia trifida) is a tall annual forb or subshrub native to much of the eastern and central United States as well as parts of Canada and Mexico. It thrives in moist, light to heavy soils with a pH between 7.5 and 8, making it adaptable but preferring slightly alkaline conditions. This plant can grow up to 2 meters in height, earning its name from its large size compared to other ragweeds. Native to Alabama, Alberta, Arizona, Arkansas, California, Colorado, Connecticut, and Delaware, Giant Ragweed is known for its edible properties, though it is more commonly recognized as a problematic weed due to its allergenic pollen. Its distinctive features include large, coarsely toothed leaves and tall stature, setting it apart from other members of the Asteraceae family.
Quick answers
What is Giant Ragweed?
Giant Ragweed (Ambrosia trifida) is a tall annual forb or subshrub native to much of the eastern and central United States as well as parts of Canada and Mexico. It thrives in moist, light to heavy soils with a pH between 7.5 and 8, making it adaptable but preferring slightly alkaline conditions.
Growingconditions · propagation · uses
VCultivation
Cultivation
Giant Ragweed thrives in light to medium soils and can tolerate heavier clay soils, though it prefers well-drained conditions. It requires moist soil and a slightly alkaline pH of 7.5–8. The plant is hardy in temperate regions but may struggle outside its native range. Giant Ragweed is an annual that grows up to 2 meters tall and benefits from full sun. For propagation, seeds can be sown directly into the garden after the last frost. Regular watering is essential during dry spells, especially when establishing the plant.
Light
9/10
Water
Moist
Soil
Light (sandy), Medium, Heavy (clay)
Hardiness
1-11
Life cycle
Annual
Habit
Subshrub, Forb/herb
Mature size
2.0 m tall
Soil pH
7.5–8
For first-time growers
How to grow Giant Ragweed for the first time
8steps
Start with Giant Ragweed as a simple annual plant, focusing on basic care.
- 1
What you'll need
Seeds, a garden plot or large container, soil, water.
- 2
Best time to plant
Plant in spring after the last frost, when temperatures are consistently above 10°C.
- 3
Soil and container prep
Choose a location with full sun. Ensure the soil is well-draining, light (sandy), medium, or heavy (clay).
- 4
Sowing or transplanting
Direct sow seeds 1-2 cm deep in rows spaced about 60 cm apart. Thin seedlings to 30 cm apart.
- 5
First two weeks
Water regularly, keeping the soil moist but not waterlogged. Monitor for pests and diseases.
- 6
Ongoing care
Continue regular watering as needed. Mulch around plants to retain moisture and suppress weeds.
- 7
Harvest or pruning
Prune back any dead or yellowing leaves to encourage new growth. No specific harvesting is necessary for Giant Ragweed.
- 8
Common mistakes
Overwatering, planting too close together, neglecting to thin seedlings.
VIEdible & utility
Edible & utility
Edible uses: Oil
Other uses:Dyeoil
Contextrange · companions · related
VIIDistribution
30 native · 0 introduced
Distribution
30 native · 0 introducedDistribution across1 continent· 30 native
Asia1 region
native (1)Georgia
Broader regions
native:Alabama, Alberta, Arizona, Arkansas, Colorado, Connecticut, Delaware, District of Columbia, Florida, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Manitoba, Maryland, Mexico Gulf, Mexico Northeast, Mexico Northwest, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Massachusetts
IXSpecimen gallery
1 image
Specimen gallery
1 imageXI
Explore further
Companion planting
Growing zone
XII
About this entry
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Back to the cataloguePlant id · ba69c9c8-f946-4318-9c24-1e6c1cb5a1e0
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