White Snakeroot
ageratina altissima
Also known as: ["Eupatorium altissimum","Ageratina altissima var. roanensis"]
Overview
A perennial herbaceous plant native to eastern North America, known for its clusters of small white flowers and toxic properties.
Benefits & Perks
["wildlife attractant (bees, butterflies, birds)","shade tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Ageratina |
| Botanical Name: | Ageratina altissima |
Plant Characteristics
Basic Information
- Category: Herbs & Weeds
- Suitable Location: garden bed or container in partial shade
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"0–35°C"}
- Hardiness: {"zones":"3–8"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Moderate to fast-draining; avoid waterlogged conditions.
- Soil Type: Well-draining, loamy soil with organic matter; can tolerate average garden soil.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: moderate
- Pruning Frequency: Light pruning can be done as needed; major pruning in late winter or early spring before new growth begins.
- Pruning Intensity: Light to moderate; avoid heavy pruning unless necessary to control size or shape.
Care Details
Ideal Sunlight Coverage:
Partial shade to full shade; tolerates low light conditions; prefers bright indirect light for several hours if available.
Sunlight Tolerance Tips:
Acclimate gradually to brighter light if moving from shade; avoid direct sunlight which can scorch leaves; place in a spot with dappled light or filtered shade.
Care Requirements
Care Difficulty
moderatemoderate
Sunlight
partial shade to full sun
Avoid direct sun; provide shade during peak hours; adjust light exposure gradually.
Watering
every 7–10 days during active growth, reduce in winter
Water thoroughly but infrequently; ensure soil dries between waterings; avoid overhead watering to prevent fungal issues.
Soil
well-drained, fertile loam
pH: Slightly acidic to neutral (pH 6.0–7.0).
Ensure good drainage; amend with organic matter; avoid compacted soil.
Temperature
Prefers cool to moderate temperatures (60–75°F or 15–24°C); can tolerate cooler conditions but avoid prolonged exposure below 50°F (10°C).
Keep away from drafts; maintain moderate temperatures; protect from extreme heat or cold.
Fertilizing
every 4–6 weeks during spring and summer
Dilute fertilizer to prevent root burn; fertilize only when actively growing; flush soil occasionally to prevent salt buildup.
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 rooting hormone (optional).
- Plant in moist propagation medium.
- Maintain humidity.
Best Time: Spring or early summer when the plant is actively growing.
Environment
High humidity, indirect light, and consistent warmth (65–75°F or 18–24°C) promote rooting.
Medium
Well-draining potting mix, such as a mix of peat and perlite or cactus mix.
Hormone
Rooting hormone is optional but can improve success rates.
Timeline
Roots may develop in 3–4 weeks; new growth may appear in 6–8 weeks.
Tools Needed
Pruning shears, rooting hormone (optional), small pots, propagation medium.
Quick Tips
Use sharp, clean tools; maintain high humidity with a plastic bag or dome; keep out of direct sun.
Pruning & Repotting
Pruning Guide
Method
Pinch back tips to encourage branching; cut just above a leaf node or bud.
Pruning Plan
Prune to maintain shape, encourage bushier growth, and remove dead or diseased parts.
Tools
Pruning shears, sharp scissors, or your fingers for small stems.
Checklist
Use clean tools; prune dead or damaged growth; shape as desired; avoid over-pruning.
Repotting Guide
Best Season
Early spring before the growing season begins.
Pot Size
Choose a pot one size larger than the current one (e.g., 2–3 inches wider in diameter).
Method
Remove the plant gently; trim any circling roots; place in a new pot with fresh soil; water lightly after repotting.
Suggestions
Repot every 2–3 years or when the plant becomes root-bound; beneficial for refreshing soil and providing more space.
Checklist
Select appropriate pot size; prepare fresh soil mix; handle roots carefully; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture before watering; water deeply at the base; ensure proper drainage; adjust frequency based on season.
How to Apply Water Properly
Water at the base of the plant, ensuring moisture reaches the root zone; water early in the morning to minimize evaporation and fungal growth; allow excess water to drain away completely.
Watering Schedule Tips
Water deeply once the top inch of soil feels dry; reduce frequency in winter to prevent root rot.
Soil Improvement
Add compost or organic matter to improve structure and fertility; mix in perlite or sand for better drainage.
Temperature Stress Management
Signs of Temperature Issues
Wilting, yellowing leaves, or stunted growth in excessive heat; leaf drop or browning in cold stress.
Cold Stress
Low temperatures can slow growth and cause leaf discoloration; prolonged cold may lead to root damage or death.
Solution: Protect from frost and cold drafts; move potted plants indoors during cold spells; use a heat mat if necessary for propagation or recovery.
Hot Stress
Excessive heat can cause wilting, leaf scorch, or reduced flowering; may lead to dehydration if water needs are not met.
Solution: Provide shade during peak heat; increase watering frequency; ensure good air circulation to reduce heat stress.
Fertilizing Guide
Fertilizing Checklist
Use diluted fertilizer; apply during active growth; avoid winter feeding; flush soil periodically.
Fertilizing Method
Use a balanced, water-soluble fertilizer diluted to half strength; fertilize monthly during the growing season (spring and summer); avoid fertilizing in fall and winter.
Common Problems & Solutions
Toxicity Warning
Cats
ToxicCats are highly sensitive to the trematol in Ageratina altissima, which can cause severe metabolic disturbances, neurological symptoms, and potentially fatal outcomes. Even small amounts can be dangerous.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
ToxicIn dogs, Ageratina altissima ingestion can cause severe gastrointestinal distress, metabolic acidosis, and neurological symptoms due to trematol toxicity. The effects can be life-threatening if not treated promptly.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
ToxicAgeratina altissima contains trematol, a toxic alcohol that inhibits the body's ability to metabolize lactate, leading to hypoglycemia, metabolic acidosis, and potentially fatal tremors or seizures. The plant's toxicity is cumulative, meaning repeated ingestion over time can lead to more severe effects.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Is White Snakeroot toxic to humans?
A: Yes, it is highly toxic to humans, causing milk sickness if ingested.
Q: Does White Snakeroot attract wildlife?
A: Yes, it attracts bees, butterflies, and birds with its flowers.
Q: Where does White Snakeroot grow best?
A: It thrives in shady, moist areas and is often found in woodlands and along streams.
Quick Reference
| Family: | Asteraceae |
| Care: | moderate |
| Light: | partial shade to full sun |
| Water: | every 7–10 days during activ |
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