Rough-leaved Rosinweed
silphium radula
Also known as: ["Rough-leaved Silphium","Rough Rosinweed"]
Overview
A robust perennial herb native to North America, characterized by rough-textured leaves and large, yellow composite flowers.
Benefits & Perks
["long-flowering","wildlife attractant (bees, butterflies, birds)","drought tolerant","aesthetic foliage"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Silphium |
| Botanical Name: | Silphium radula |
Plant Characteristics
Basic Information
- Category: Flowers
- Suitable Location: garden bed or container in a sunny spot
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"5–35°C"}
- Hardiness: {"zones":"5–8"}
- Misting: rarely required
- Drainage: Fast-draining to prevent waterlogging.
- Soil Type: Well-draining, loamy soil with added organic matter.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: high
- Pruning Frequency: Annually in late winter or early spring; light pruning can be done as needed.
- Pruning Intensity: Moderate; remove up to one-third of old growth if necessary.
Care Details
Ideal Sunlight Coverage:
Full sun (6–8 hours/day); tolerates partial shade in hot climates.
Sunlight Tolerance Tips:
Acclimate gradually to intense sunlight; protect from harsh afternoon sun; adjust placement based on seasonal light changes.
Care Requirements
Care Difficulty
moderatemoderate
Sunlight
full sun to partial shade
Rotate plant for even growth; use sheer curtains in intense sun; move outdoors in spring/summer.
Watering
every 7–10 days during growing season, reduce in winter
Water thoroughly but infrequently; ensure soil dries between waterings; avoid overwatering.
Soil
well-draining, loamy soil
pH: Slightly acidic to neutral (pH 6.0–7.0).
Use raised beds for drainage; avoid heavy clay soils; amend with organic matter annually.
Temperature
Prefers 60–85°F (15–29°C); tolerates mild frosts but thrives in warm conditions.
Avoid sudden temperature shifts; protect from drafts; maintain consistent warmth during active growth.
Fertilizing
every 4–6 weeks during active growth
Fertilize in spring/summer only; flush soil occasionally to prevent salt buildup; use organic options for gentle feeding.
Propagation
Methods
Stem cuttings or division; stem cuttings are more common for home growers.
Step-by-Step Propagation Guide
- Take a 4–6 inch cutting.
- Remove lower leaves.
- Dip in hormone.
- Plant in medium.
- Keep moist and warm.
Best Time: Spring or early summer when the plant is actively growing.
Environment
Warm (70–75°F), high humidity, and bright indirect light.
Medium
Well-draining mix of perlite and peat moss or cactus soil.
Hormone
Rooting hormone is optional but recommended for faster rooting.
Timeline
Roots develop in 3–6 weeks; new growth appears in 2–3 months.
Tools Needed
Pruners, rooting hormone, small pots, well-draining medium.
Quick Tips
Use sterile tools; maintain humidity with a plastic bag; avoid overwatering cuttings.
Pruning & Repotting
Pruning Guide
Method
Cut stems just above a leaf node or bud; thin out crowded areas.
Pruning Plan
Remove dead or damaged stems to improve air circulation and shape; encourage bushier growth.
Tools
Pruning shears, sterilizing solution, gloves.
Checklist
Sterilize tools; prune dead/damaged growth; shape plant; clean up debris.
Repotting Guide
Best Season
Early spring before active growth begins.
Pot Size
Choose a pot 1–2 inches larger in diameter than the current one.
Method
Remove plant gently; trim roots if crowded; place in new pot with fresh soil; water lightly.
Suggestions
Repot every 2–3 years or when roots fill the pot; beneficial for growth and soil health.
Checklist
Check root bound status; prepare new pot; use fresh soil; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture; water deeply; ensure drainage; adjust for season.
How to Apply Water Properly
Water at the base of the plant, ensuring moisture reaches the root zone; allow excess water to drain away; water in the morning to reduce evaporation.
Watering Schedule Tips
Water deeply once the top inch of soil feels dry; reduce frequency in winter to prevent root rot.
Soil Improvement
Add perlite or sand for drainage; incorporate compost for fertility; ensure good aeration.
Temperature Stress Management
Signs of Temperature Issues
Wilting, leaf drop, or stunted growth in extreme heat or cold.
Cold Stress
Slows growth; may cause leaf discoloration or dieback in prolonged cold.
Solution: Provide frost protection; move indoors in freezing temperatures; ensure good air circulation.
Hot Stress
Leaves may scorch or wilt; growth may slow in excessive heat.
Solution: Provide afternoon shade; increase watering; use mulch to retain soil moisture.
Fertilizing Guide
Fertilizing Checklist
Check season; dilute fertilizer; apply to moist soil; avoid foliage contact.
Fertilizing Method
Use balanced liquid fertilizer diluted to half strength every 4–6 weeks during growing season; avoid fertilizing in winter.
Common Problems & Solutions
Toxicity Warning
Cats
Slightly ToxicCats may experience mild gastrointestinal upset if they ingest Silphium radula. The plant is not highly toxic but can cause discomfort in sensitive individuals.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
Slightly ToxicIn dogs, ingestion of Silphium radula may lead to mild gastrointestinal upset. The plant does not typically cause severe toxicity but can cause discomfort if consumed in large amounts.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
Slightly ToxicSilphium radula contains compounds that can cause mild gastrointestinal distress when ingested in significant quantities. The plant's physiological impact is primarily localized to the digestive system, with minimal systemic effects.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: How tall does Silphium radula grow?
A: It typically reaches 3–6 feet in height.
Q: Does it require full sun?
A: Yes, it thrives in full sun to partial shade.
Q: Is it suitable for dry conditions?
A: Yes, it is drought-tolerant once established.
Quick Reference
| Family: | Asteraceae |
| Care: | moderate |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during growi |
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