Photo: Krzysztof Ziarnek KenraizCC BY-SA 4.0via Wikimedia Commonsresized / cropped
Western Ragweed Plant Care
Ambrosia psilostachya DC.
Updated · Sources · How we source care data
Ambrosia psilostachya is a species of ragweed known by the common names Cuman ragweed and perennial ragweed, and western ragweed.
Every 3–5 days
Full sun to partial shade
60–80°F
40–60%
At a glance
How do you care for Western Ragweed?
Water Western Ragweed every 3–5 days, letting the top layer of soil dry out between waterings, and give it full sun to partial shade. It prefers temperatures of 60–80°F (16–27°C) and 40–60% humidity. Fertilize it every 6 months during the growing season. It is reported as toxic to pets, so keep it out of reach of pets.
What Is the Western Ragweed?
Western Ragweed (Ambrosia psilostachya) belongs to the Asteraceae family within the Ambrosia genus. Western Ragweed is also known as Cuman Ragweed, Poverty Weed, Ambrosia californica.
Western Ragweed displays a spreading herbaceous perennial growth habit, reaching up to 2 ft tall with a spread of approximately 3 ft. Western Ragweed produces small green flowers in inconspicuous clusters.
Leaf size: approximately 4 inches.
How Often Should You Water a Western Ragweed?
Ambrosia psilostachya requires watering every 3–5 days. Allow the top layer of soil to dry between waterings to prevent root rot. Reduce watering frequency during winter when growth slows.
Watering Frequency
Every 3–5 days
Let soil partially dry between waterings
What Light Does the Western Ragweed Need?
Western Ragweed thrives in full sun to partial shade.
Light Requirement
Full sun to partial shade
What Temperature and Humidity Does the Western Ragweed Prefer?
Ambrosia psilostachya grows best at temperatures of 60–80°F. Western Ragweed prefers humidity levels of 40–60%.
Temperature
60–80°F
Humidity
40–60%
What Soil Mix Works Best for a Western Ragweed?
Well-draining sandy soil mix with added organic matter. Good drainage is essential for Western Ragweed to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Western Ragweed?
Feed Western Ragweed every 6 months during the growing season (spring and summer) with a balanced fertilizer diluted to the strength on the label.
Pause feeding in autumn and winter, when growth slows, and never fertilize dry soil — water first.
Fertilizing
Every 6 months
During the growing season
The PlantoScan app can remind you when to water and when to fertilize each plant.
How Do You Repot a Western Ragweed?
Repot every 1-2 years in early spring. Choose a pot one size larger than the current container, and ensure it has drainage holes to allow excess water to escape.
How Do You Propagate a Western Ragweed?
Western Ragweed can be propagated through seeds. Similar propagation techniques also apply to common ragweed plant care, which shares the same genus.
Is the Western Ragweed Toxic to Pets and Children?
Toxic (caution)
Reported as toxic in our plant data. Not verified by the ASPCA.
Toxic to humans and pets if ingested
This is a general caution, not veterinary or medical advice. If your pet ate a plant, contact your vet or animal poison control.
See all plants toxic to cats and plants toxic to dogs.
What Pests and Diseases Affect the Western Ragweed?
Western Ragweed is susceptible to aphids, spider mites, whiteflies. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.
Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.
What USDA Hardiness Zone Does the Western Ragweed Need?
Western Ragweed grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. In cooler regions, grow Western Ragweed as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 13a
Keep exploring plants
Western Ragweed is one of many species covered in the complete plant care and identification guide, which groups plants by genus, attribute, and popularity.
It belongs to the Ambrosia genus — compare its care with other Ambrosia species on PlantoScan.
Ambrosia is part of the Asteraceae plant family — browse all Asteraceae genera and species.
Western Ragweed thrives in bright light and direct sun — see other bright-light plants.
More Ambrosia Species
Other Ambrosia species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Ambrosia psilostachya DC., family Asteraceae (first published in Prodr. [A. P. de Candolle] 5: 526. 1836 [1-10 Oct 1836]) — World Flora Online record, IPNI name record.
- Pet toxicity: Western Ragweed is reported as toxic to pets in our plant data (not verified by the ASPCA), so treat it with caution. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
- Photo: Krzysztof Ziarnek Kenraiz, CC BY-SA 4.0, Wikimedia Commons — original.
- Hardiness zone: USDA Zone 13a, calculated from the plant's minimum temperature.
- Care values(watering, light, temperature, humidity, soil, fertilizing): PlantoScan's plant database, filtered by automatic plausibility checks — values that fail them are hidden. How we source and check plant data.
Spotted a mistake? Email info@upvision.media with the page link — we check and correct reported errors.
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