Toothed Rosinweed
Silphium dentatum
Not currently listed at our partner nurseries.
Essentials
At a Glance
Plant Type
Perennial
Height
60 inches
Width
36 inches
Light
Full Sun, Partial Sun
Zones
5, 6, 7, 8, 9
Water
Low to moderate
Humidity
Average garden humidity
Lifespan
Perennial
Native To
North America
Toxicity
Non-toxic to humans and pets
The Story
Plant Bio
Silphium dentatum, or Toothed Rosinweed, is a tall, upright perennial with stout, hairy stems. It features rough, lance-shaped to ovate leaves with toothed margins and produces bright yellow, sunflower-like flowerheads in summer. This species is notable for its drought tolerance and ability to thrive in poor soils, making it a valuable plant for prairie and xeriscape 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, then reduce watering.
- Provide full sun for optimal growth.
- Mulch around the base to retain moisture.
- Divide clumps every 3-4 years in early spring.
- Stake tall plants if needed to prevent wind damage.
Pro Tip
Allow seed heads to mature for natural reseeding and wildlife benefits.
Keep It Thriving
Care Guide
Do
- Water during dry spells to keep soil moist 🌱
- Prune back after flowering to maintain shape
- Apply a balanced fertilizer in early spring
- Mulch to conserve moisture
Don't
- Overwater to prevent root rot ❌
- Avoid heavy fertilization which can promote disease
- Don't disturb roots when dividing
- Refrain from using chemical pesticides near pollinators
Seasonal Care Calendar
| Task | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Prune | ||||||||||||
| Spring Cleanup | ||||||||||||
| Winter Prep |
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
Toothed Rosinweed questions
What zones can Toothed Rosinweed grow in?
Toothed Rosinweed is hardy in USDA Zones 5–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.
Is Toothed Rosinweed deer resistant?
Yes — Toothed Rosinweed is rated deer-resistant. Deer typically pass it over, though extreme hunger can override any plant's defenses.
When does Toothed Rosinweed bloom?
Toothed 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 Toothed Rosinweed need full sun?
Toothed Rosinweed does best in full sun to part shade. In hot climates, afternoon shade keeps blooms fresher longer.
Is Toothed Rosinweed drought tolerant?
Yes — once established (usually after the first full season), Toothed 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 Toothed 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.
