Giant Ragweed
conyza sumatrensis
Also known as: ["Hairy Fleabane","Sumatran Fleabane"]
Overview
An annual herbaceous plant native to tropical regions, known for its rapid growth and prolific seed production.
Benefits & Perks
["fast growing","wildlife attractant (bees, butterflies, birds)","drought tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Conyza |
| Botanical Name: | Conyza sumatrensis |
Plant Characteristics
Basic Information
- Category: Herbs & Weeds
- Suitable Location: open garden beds or disturbed areas with good sunlight exposure
- Suitable For:
- Is Weed: No
- Allergenicity: high
Environmental Needs
- Climate: {"temperatureRange":"10–35°C"}
- Hardiness: {"zones":"8–11"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Fast-draining to prevent waterlogging.
- Soil Type: Well-draining, sandy loam with added organic matter.
Maintenance Level
- Maintenance Level: very low
- Toughness Level: very high
- Pruning Frequency: As needed, typically every 2–3 months or after flowering.
- Pruning Intensity: Moderate; remove up to one-third of growth at a time.
Care Details
Ideal Sunlight Coverage:
Full sun (6–8 hours/day); tolerates partial shade but may become leggy.
Sunlight Tolerance Tips:
Acclimate plants gradually to intense sunlight; protect from harsh midday sun in hot climates; ensure good air circulation to prevent mildew.
Care Requirements
Care Difficulty
very easyeasy
Sunlight
full sun to partial shade
Rotate plant for even growth; provide shade during extreme heat; avoid direct sun on leaves in high temperatures.
Watering
every 7–10 days during active growth, less frequently in dormant periods
Water thoroughly but infrequently; ensure soil dries between waterings; avoid overhead watering to prevent fungal issues.
Soil
well-drained, sandy loam with moderate organic content
pH: Slightly acidic to neutral (pH 6.0–7.0).
Avoid heavy clay soils; ensure pots have drainage holes; topdress with compost annually.
Temperature
Prefers warm conditions (65–85°F/18–29°C); sensitive to frost.
Avoid sudden temperature changes; protect from drafts; maintain consistent warmth.
Fertilizing
every 4–6 weeks during growing season, not required otherwise
Fertilize sparingly to avoid leggy growth; flush soil occasionally to prevent salt buildup; apply in early morning or late evening.
Propagation
Methods
Stem cuttings or seed; stem cuttings are faster and more reliable.
Step-by-Step Propagation Guide
- Take 4–6 inch cuttings.
- Remove lower leaves.
- Dip in rooting hormone.
- Plant in medium.
- Keep moist and warm.
Best Time: Spring or early summer when temperatures are warm and light is strong.
Environment
Warm (70–75°F/21–24°C), high humidity (70–80%), 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 2–4 weeks; new growth appears in 6–8 weeks.
Tools Needed
Pruning shears, rooting hormone, small pots, misting spray bottle.
Quick Tips
Use healthy, non-flowering stems; keep soil consistently moist but not waterlogged; provide bottom heat if possible.
Pruning & Repotting
Pruning Guide
Method
Pinch back tips for bushier growth; cut just above a leaf node or lateral branch.
Pruning Plan
Prune to maintain shape, encourage bushiness, and remove dead or diseased growth.
Tools
Clean, sharp pruning shears or scissors.
Checklist
Sterilize tools; prune dead/damaged growth; shape plant; clean up debris.
Repotting Guide
Best Season
Spring, before the active growing season begins.
Pot Size
Increase pot size by 1–2 inches in diameter.
Method
Remove plant gently; trim roots if necessary; 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 new pot; prepare fresh soil; handle roots carefully; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture; water deeply; ensure drainage; avoid wetting leaves.
How to Apply Water Properly
Water at the base of the plant, ensuring moisture reaches the root zone; water until it drains from the bottom; avoid wetting foliage.
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 coarse sand for drainage; incorporate compost for fertility; ensure aeration with organic matter.
Temperature Stress Management
Signs of Temperature Issues
Wilting, yellowing leaves, stunted growth, or bud drop in extreme heat or cold.
Cold Stress
Growth slows or halts; leaves may turn purple or brown; risk of frost damage.
Solution: Move to a warmer location; provide frost protection; avoid overwatering in cold conditions.
Hot Stress
Leaves may scorch, wilt, or drop; growth may slow; flowers may fail to set.
Solution: Provide shade during peak heat; increase watering; improve air circulation.
Fertilizing Guide
Fertilizing Checklist
Check fertilizer type; dilute properly; apply to moist soil; avoid contact with leaves.
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
ToxicCats are also susceptible to the hepatotoxic effects of pyrrolizidine alkaloids found in Conyza sumatrensis, which can lead to severe liver damage and failure.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
ToxicThe pyrrolizidine alkaloids in Conyza sumatrensis are toxic to dogs, causing liver damage and potential liver failure if ingested in significant quantities.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
ToxicConyza sumatrensis contains pyrrolizidine alkaloids, which are hepatotoxic and can cause liver damage upon ingestion. Chronic exposure may lead to severe liver fibrosis and even cirrhosis.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Is Conyza sumatrensis invasive?
A: Yes, it is considered an invasive weed in many regions due to its rapid growth and seed dispersal.
Q: Does it cause allergies?
A: Yes, it is a known allergen, particularly for those with hay fever.
Q: How can it be controlled?
A: Mechanical removal or herbicides are effective methods for controlling its spread.
Quick Reference
| Family: | Asteraceae |
| Care: | very easy |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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