Siam weed
chromolaena odorata
Also known as: ["Tridax grandiflora","Eupatorium odoratum"]
Overview
A fast-growing, invasive shrub with fragrant leaves and white flowers, native to the Americas but widely naturalized in tropical regions.
Benefits & Perks
["fast growing","fragrant flowers","wildlife attractant (bees, butterflies, birds)","drought tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Chromolaena |
| Botanical Name: | Chromolaena odorata |
Plant Characteristics
Basic Information
- Category: Flowers
- Suitable Location: outdoor garden bed in tropical or subtropical regions
- Suitable For:
- Is Weed: No
- Allergenicity: moderate
Environmental Needs
- Climate: {"temperatureRange":"20–35°C"}
- Hardiness: {"zones":"9–11"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Fast-draining to prevent waterlogging.
- Soil Type: Well-draining, fertile soil; mix of garden soil, compost, and sand or perlite.
Maintenance Level
- Maintenance Level: very low
- Toughness Level: very high
- Pruning Frequency: Every 2–3 months during growing season; after flowering to promote new blooms.
- Pruning Intensity: Moderate; remove up to one-third of growth if overgrown.
Care Details
Ideal Sunlight Coverage:
Full sun to partial shade; 6–8 hours of direct sunlight daily; adjust for intense summer heat.
Sunlight Tolerance Tips:
Acclimate plants gradually to intense sunlight; protect from harsh midday sun; adjust placement based on indoor/outdoor conditions.
Care Requirements
Care Difficulty
easyeasy
Sunlight
full sun to partial shade
Rotate plant for even light exposure; use sheer curtains to filter intense sun; move outdoors in spring/summer.
Watering
every 7–10 days during active growth, less frequently in dormant periods
Water thoroughly until it drains from the bottom; allow soil to dry between waterings; avoid overwatering.
Soil
well-draining, fertile loam
pH: Slightly acidic to neutral (pH 6.0–7.0).
Use well-draining mix; avoid heavy clay soils; amend with organic matter for fertility.
Temperature
Thrives in warm conditions, 20–30°C; tolerates brief periods above 35°C; sensitive to frost.
Protect from frost; provide shade in extreme heat; maintain consistent warmth for best growth.
Fertilizing
every 4–6 weeks during growing season, none in winter
Apply fertilizer after watering to prevent root burn; switch to low-nitrogen formula for flowering; flush soil occasionally to prevent salt buildup.
Propagation
Methods
Stem cuttings; softwood cuttings root easily in warm conditions.
Step-by-Step Propagation Guide
- Take 4–6 inch cuttings.
- Remove lower leaves.
- Dip in rooting hormone.
- Plant in medium.
- Maintain humidity.
Best Time: Spring or early summer when growth is active.
Environment
High humidity (70–90%), warm temperatures (20–25°C), indirect light.
Medium
Well-draining mix of peat and perlite or sand.
Hormone
Rooting hormone is optional but recommended for faster rooting.
Timeline
Roots develop in 2–4 weeks; establish in new pot within 2–3 months.
Tools Needed
Pruning shears, rooting hormone, small pots, plastic bags or propagator.
Quick Tips
Use healthy, non-flowering stems; maintain consistent moisture; provide bottom heat for faster rooting.
Pruning & Repotting
Pruning Guide
Method
Pinch back tips for bushiness; cut stems just above a leaf node.
Pruning Plan
Regular pruning to maintain shape and encourage bushier growth; remove dead or overgrown stems.
Tools
Pruning shears, sharp knife, gloves.
Checklist
Sterilize tools; prune dead/damaged stems; shape plant; clean up debris.
Repotting Guide
Best Season
Spring, before new growth begins.
Pot Size
Increase pot size by 2–5 cm in diameter; ensure good drainage.
Method
Remove plant gently; trim roots if needed; place in new pot with fresh soil; water lightly.
Suggestions
Repot every 1–2 years or when roots fill the pot; beneficial for growth and health.
Checklist
Choose appropriate pot; prepare fresh soil mix; handle roots carefully; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture; water thoroughly; ensure drainage; adjust for season.
How to Apply Water Properly
Water directly at the root zone, ensuring even saturation; water early in the morning to reduce evaporation; ensure excess water drains away to prevent waterlogging.
Watering Schedule Tips
Water deeply once the top inch of soil feels dry; reduce frequency in winter to prevent root rot.
Soil Improvement
Add organic matter like compost; incorporate perlite or sand for drainage; ensure aeration with coarse materials.
Temperature Stress Management
Signs of Temperature Issues
Wilting, yellowing leaves, stunted growth, or leaf drop in extreme heat or cold.
Cold Stress
Growth slows or halts; leaves may turn yellow or brown; risk of frost damage or death in prolonged cold.
Solution: Move to a warmer location; provide frost protection; avoid watering during cold spells.
Hot Stress
Leaf scorch, wilting, or drooping; reduced flowering; potential for heat stress in prolonged high temperatures.
Solution: Provide shade during peak heat; increase humidity; water more frequently but avoid waterlogging.
Fertilizing Guide
Fertilizing Checklist
Use diluted fertilizer; apply during growing season; avoid winter feeding; flush soil periodically.
Fertilizing Method
Use balanced liquid fertilizer diluted to half strength; fertilize every 4–6 weeks during growing season (spring/summer); avoid fertilizing in winter.
Common Problems & Solutions
Toxicity Warning
Cats
ToxicChromolaena odorata is toxic to cats when ingested, causing gastrointestinal distress and potential systemic effects. The plant's compounds can lead to irritation and inflammation in the digestive system.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
ToxicChromolaena odorata is toxic to dogs when ingested, leading to gastrointestinal upset and potential systemic toxicity. The plant's compounds can cause irritation and inflammation in the digestive tract.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
ToxicChromolaena odorata is toxic to humans when ingested, causing gastrointestinal distress and potential systemic effects. The plant contains sesquiterpene lactones and other compounds that can irritate mucous membranes and disrupt normal physiological functions.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Is Chromolaena odorata safe for pets?
A: No, it is toxic to dogs and cats.
Q: How does Chromolaena odorata spread?
A: It spreads rapidly through seeds and vegetative growth, making it highly invasive.
Q: Can Chromolaena odorata be used for medicinal purposes?
A: Traditional uses exist, but it is not widely recognized for medicinal value and can be toxic.
Quick Reference
| Family: | Asteraceae |
| Care: | easy |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
Get Expert Care Tips
Download the Plantious app for personalized care reminders and plant identification!
Google Play App Store
