Twinleaf Sunflower
helianthus decapetalus
Also known as: ["Ten-petaled Sunflower","Decapetalous Sunflower"]
Overview
A deciduous herbaceous perennial native to eastern North America, known for its bright yellow flowers and distinctive twin-lobed leaves.
Benefits & Perks
["long-flowering","wildlife attractant (bees, butterflies, birds)","drought tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Helianthus |
| Botanical Name: | Helianthus decapetalus |
Plant Characteristics
Basic Information
- Category: Flowers
- Suitable Location: garden bed with partial shade in afternoon
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"5–35°C"}
- Hardiness: {"zones":"3–9"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Moderately well-draining; avoid waterlogged conditions.
- Soil Type: Rich, loamy soil with good organic matter content; well-draining but moisture-retentive.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: moderate
- Pruning Frequency: Annually in late winter or early spring; light pruning can be done after flowering if needed.
- Pruning Intensity: Moderate; remove up to one-third of the oldest stems to encourage new growth.
Care Details
Ideal Sunlight Coverage:
Full sun (6–8 hours of direct sunlight daily); tolerates partial shade but may produce fewer flowers.
Sunlight Tolerance Tips:
Acclimate plants gradually if moving from shade to sun; protect from intense midday sun in hot climates; ensure good air circulation to prevent mildew in shaded areas.
Care Requirements
Care Difficulty
easymoderate
Sunlight
full sun to partial shade
Rotate plants for even growth; use shade cloth in extreme heat; avoid placing in drafty areas.
Watering
every 7–10 days during active growth, reduce in winter
Water thoroughly but infrequently to encourage deep roots; avoid overhead watering to prevent fungal issues; ensure soil dries slightly between waterings.
Soil
moist, fertile, well-drained loam
pH: Slightly acidic to neutral (pH 6.0–7.0).
Test soil pH annually; amend as needed; ensure proper drainage to prevent root rot.
Temperature
Prefers 65–85°F (18–29°C); tolerates cooler temperatures but may become dormant below 50°F (10°C); thrives in warm, humid conditions.
Monitor temperature changes; adjust watering and light accordingly; protect from sudden temperature shifts.
Fertilizing
every 2–3 months during spring and summer
Fertilize lightly and frequently rather than heavily; stop fertilizing in late summer to allow for hardening off before winter; water thoroughly after fertilizing to prevent root burn.
Propagation
Methods
Stem cuttings or division of rhizomes; seeds can also be sown in early spring.
Step-by-Step Propagation Guide
- Select healthy stems or rhizomes.
- Prepare cuttings or divisions.
- Apply rooting hormone if using.
- Plant in medium.
- Maintain humidity and warmth.
- Transplant once rooted.
Best Time: Early spring for cuttings or division; late winter/early spring for seeds.
Environment
High humidity (70–80%), warm temperatures (70–75°F or 21–24°C), and bright indirect light.
Medium
Well-draining potting mix with perlite or sand; peat moss can be added for moisture retention.
Hormone
Rooting hormone is optional but recommended for stem cuttings to improve success rate.
Timeline
Stem cuttings root in 3–4 weeks; division establishes quickly in 1–2 weeks; seeds germinate in 2–4 weeks with indoor stratification.
Tools Needed
Pruning shears, rooting hormone, pots, well-draining medium, plastic wrap or propagation dome.
Quick Tips
Use sharp, sterile tools to prevent disease; keep soil consistently moist but not waterlogged; provide bottom heat for faster rooting.
Pruning & Repotting
Pruning Guide
Method
Cut stems back to a healthy bud or lateral branch; remove crossing or rubbing branches; thin out dense growth.
Pruning Plan
Remove dead or damaged stems; thin overcrowded growth to improve air circulation; shape plant for aesthetic appeal and health.
Tools
Pruning shears, loppers (for thicker stems), gloves, disinfectant for tools.
Checklist
Disinfect tools before use; prune during dormancy; make clean cuts; remove debris after pruning.
Repotting Guide
Best Season
Early spring before active growth begins.
Pot Size
Increase pot size by 2–3 inches in diameter; ensure the new pot has drainage holes.
Method
Remove plant gently; trim any circling roots; place in a new pot with fresh soil; water thoroughly after repotting.
Suggestions
Repot every 2–3 years or when roots fill the container; beneficial for container-grown plants to refresh soil and provide space.
Checklist
Choose the right pot size; use fresh, well-draining soil; water after repotting; avoid fertilizing for 4–6 weeks.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture before watering; water deeply at the base; avoid wetting foliage; ensure proper drainage.
How to Apply Water Properly
Apply water directly to the root zone, ensuring even saturation to a depth of 6–8 inches; allow excess water to drain away; water early in the morning to minimize evaporation and fungal growth.
Watering Schedule Tips
Water deeply once a week during active growth, increasing frequency to twice weekly in hot, dry periods; reduce watering in winter to once every 3–4 weeks.
Soil Improvement
Add compost or well-rotted manure to enhance fertility; incorporate perlite or sand for drainage; use mulch to retain moisture and suppress weeds.
Temperature Stress Management
Signs of Temperature Issues
Chlorosis or necrosis in extreme heat; stunted growth or bud drop in cold stress; wilting or leaf drop in temperature fluctuations.
Cold Stress
Growth slows or halts; leaves may turn yellow or brown; plant may enter dormancy or dieback in severe cold.
Solution: Mulch heavily around the base; move potted plants indoors or to a sheltered location; provide frost protection in late fall/early winter.
Hot Stress
Leaves may scorch, wilt, or drop; flowers may fade quickly; growth may become leggy or sparse.
Solution: Provide afternoon shade; increase watering frequency; use reflective mulch to reduce soil temperature; mist foliage during extreme heat.
Fertilizing Guide
Fertilizing Checklist
Use the correct fertilizer type; dilute to recommended strength; apply during active growth; avoid fertilizing dormant plants.
Fertilizing Method
Use a balanced, slow-release fertilizer in early spring; apply a diluted liquid fertilizer monthly during growing season; avoid high-nitrogen fertilizers to prevent excessive foliage growth.
Common Problems & Solutions
Toxicity Warning
Cats
Non-toxicHelianthus decapetalus is not toxic to cats. The plant does not contain any known toxic substances that would harm felines if ingested.
⚡ Toxic If:
if eaten
Dogs
Non-toxicHelianthus decapetalus is not toxic to dogs. There are no known toxic compounds in this plant that would pose a health risk to canines upon ingestion.
⚡ Toxic If:
if eaten
Humans
Non-toxicHelianthus decapetalus, commonly known as tenpetal sunflower, is not considered toxic to humans. It is generally safe for consumption and does not produce any known toxic compounds that would cause adverse physiological effects.
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Does Helianthus decapetalus attract wildlife?
A: Yes, it is highly attractive to bees, butterflies, and birds.
Q: Is this plant toxic to pets?
A: No, it is non-toxic to dogs and cats.
Q: How difficult is it to grow?
A: It is relatively easy to grow, requiring moderate maintenance.
Quick Reference
| Family: | Asteraceae |
| Care: | easy |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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