Mohr's rosinweed Plant Care
Silphium mohrii Small
Updated · Sources · How we source care data
Silphium mohrii, known by the common names Mohr's rosinweed and shaggy rosinweed, is a species of flowering plant in the family Asteraceae. It is native to the Southeastern United States, where it is native only to northern Alabama, southern Tennessee, and extreme northwest Georgia.
Every 7–14 days
Full sun
60–80°F
40–70%
At a glance
How do you care for Mohr's rosinweed?
Water Mohr's rosinweed every 7–14 days, letting the top layer of soil dry out between waterings, and give it full sun. It prefers temperatures of 60–80°F (16–27°C) and 40–70% humidity. Fertilize it every 6 months during the growing season.
Where Is the Mohr's rosinweed Native To?
What Is the Mohr's rosinweed?
Mohr's rosinweed (Silphium mohrii) belongs to the Asteraceae family within the Silphium genus. Mohr's rosinweed is native to the Southeastern United States.
Mohr's rosinweed displays a tall, upright perennial growth habit, reaching up to 6 ft tall with a spread of approximately 3 ft. Mohr's rosinweed produces large yellow composite flowers in late summer.
Leaf size: approximately 8 inches.
How Often Should You Water a Mohr's rosinweed?
Silphium mohrii requires watering every 7–14 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 7–14 days
Let soil partially dry between waterings
What Light Does the Mohr's rosinweed Need?
Mohr's rosinweed thrives in full sun.
Light Requirement
Full sun
What Temperature and Humidity Does the Mohr's rosinweed Prefer?
Silphium mohrii grows best at temperatures of 60–80°F. Mohr's rosinweed prefers humidity levels of 40–70%.
Temperature
60–80°F
Humidity
40–70%
What Soil Mix Works Best for a Mohr's rosinweed?
Well-draining loamy soil with added compost for nutrients. Good drainage is essential for Mohr's rosinweed to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Mohr's rosinweed?
Feed Mohr's rosinweed 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 Mohr's rosinweed?
Repot every 3-4 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 Mohr's rosinweed?
Mohr's rosinweed can be propagated through seeds, division of rhizomes. Similar propagation techniques also apply to compass plant plant care, which shares the same genus.
Is the Mohr's rosinweed Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Mohr's rosinweed, so we can't confirm whether it is safe for cats and dogs. Keep pets from chewing it as a precaution.
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 Mohr's rosinweed?
Mohr's rosinweed is susceptible to aphids, caterpillars, spider mites. 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 Mohr's rosinweed Need?
Mohr's rosinweed grows outdoors in USDA Zone 13a. It survives winters down to planting zone 13a. Mohr's rosinweed is native to the Southeastern United States. In cooler regions, grow Mohr's rosinweed as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 13a
Keep exploring plants
Mohr's rosinweed 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 Silphium genus — compare its care with other Silphium species on PlantoScan.
Silphium is part of the Asteraceae plant family — browse all Asteraceae genera and species.
Mohr's rosinweed thrives in bright light and direct sun — see other bright-light plants.
More Silphium Species
Other Silphium species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Silphium mohrii Small, family Asteraceae (first published in Bull. Torrey Bot. Club 24(11): 493. 1897 [30 Nov 1897]) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Mohr's rosinweed, so we can't confirm whether it is safe for cats and dogs. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
- 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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