Roughstem Rosinweed
Silphium radula
Not currently listed at our partner nurseries.
Essentials
At a Glance
Plant Type
Perennial
Height
48 inches
Width
36 inches
Light
Full Sun
Zones
4, 5, 6, 7, 8, 9
Water
Low to moderate
Humidity
Average
Lifespan
Perennial
Native To
North America
Toxicity
Non-toxic
The Story
Plant Bio
Silphium radula is a tall, coarse perennial with rough, sandpapery stems and leaves. It produces bright yellow, sunflower-like flowerheads on sturdy stalks in summer. This species is distinguished by its drought tolerance and ability to thrive in rocky, well-drained soils, making it an excellent choice for xeriscaping and native plant gardens.
Bloom Period:
Uses & Benefits:
Marketplace
Where to Buy
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Planting
How to Grow
- Tuck seeds into well-draining soil in early spring
- Water regularly until established, about 2 weeks
- Thin seedlings to prevent overcrowding
- Apply mulch to conserve moisture
- Stake young plants for support if needed
- Divide clumps every 3-4 years in early spring
Pro Tip
Ensure excellent drainage to prevent root rot and promote healthy growth.
Keep It Thriving
Care Guide
Do
- Water deeply during dry periods 🌱
- Prune back after flowering to maintain shape
- Apply compost annually for nutrients
Don't
- Avoid overwatering in winter ❌
- Don’t disturb roots excessively during dividing
- Refrain from fertilizing late in the season
Seasonal Care Calendar
| Task | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Spring Cleanup | ||||||||||||
| Stake |
Watch Out For
Pests & Diseases
Common Pests
Common Diseases
In the Garden
Landscape Uses & Companions
Landscape Uses
Companion Plants
Multiply
Propagation Methods
Good to Know
Common Questions
Roughstem Rosinweed questions
What zones can Roughstem Rosinweed grow in?
Roughstem Rosinweed is hardy in USDA Zones 4–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.
Is Roughstem Rosinweed deer resistant?
Yes — Roughstem Rosinweed is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.
When does Roughstem Rosinweed bloom?
Roughstem Rosinweed typically blooms in mid-summer through late summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.
Does Roughstem Rosinweed need full sun?
Roughstem Rosinweed does best in full sun (6+ hours).
Is Roughstem Rosinweed drought tolerant?
Yes — once established (usually after the first full season), Roughstem Rosinweed handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.
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Grow Roughstem Rosinweed with confidence
See it in a design of your actual yard, get zone-matched care reminders, and track it season by season in your garden journal.
