Horseweed, Canadian Fleabane

conyza canadensis

Also known as: ["Canadian Fleabane","Bastard Moxie","Butterweed","Dog Fennel","Marsh Fleabane","Musk Weed","St. Fiacre's Herb","St. Fiacre's Plant","St. Fiacre's Weed","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. Fiacre's Wort","St. 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Botanical Classification

Botanical Name: Conyza canadensis

Plant Characteristics

Basic Information
  • Suitable Location: open, disturbed areas, fields, or gardens
Environmental Needs
  • Climate: {"temperatureRange":"5–35°C"}
  • Hardiness: {"zones":"3–9"}
  • Misting: rarely required
  • Drainage: Fast-draining to prevent waterlogging.
  • Soil Type: Well-draining, loamy soil with added organic matter; cactus or succulent mix works well.
Maintenance Level
  • Pruning Frequency: As needed, but generally every 2–3 months or after flowering.
  • Pruning Intensity: Light to moderate; avoid heavy pruning unless necessary to control size.
Care Details

Ideal Sunlight Coverage:
Full sun (6–8 hours of direct sunlight daily); tolerates partial shade but may become leggy.

Sunlight Tolerance Tips:
Acclimate seedlings gradually to direct sun to avoid scorching; for indoor plants, place near a south-facing window; outdoor plants thrive in open, sunny locations.

Warning Signs: Yellowing leaves (overwatering or poor drainage); stunted growth (nutrient deficiency or compacted soil).

Care Requirements

Care Difficulty

easy

Sunlight

full sun

Rotate plants for even growth; use shade cloth if scorching occurs; supplement with grow lights if indoors.

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 or loamy soil

pH: Slightly acidic to neutral (pH 6.0–7.0).

Use a mix of potting soil and perlite; avoid heavy clay soils; ensure pots have drainage holes.

Temperature

Prefers warm temperatures (65–85°F or 18–29°C); tolerates heat but may struggle below 50°F (10°C).

Avoid sudden temperature fluctuations; protect from frost; ensure good air circulation in hot weather.

Fertilizing

rarely required, if used then monthly during active growth

Apply fertilizer to moist soil to prevent root burn; flush soil occasionally to prevent salt buildup; stop fertilizing if plant shows signs of stress.

Propagation

Methods

Stem cuttings or seed; stem cuttings root easily in water or soil.

Step-by-Step Propagation Guide
  1. Take a 4–6 inch cutting below a node.
  2. Remove lower leaves.
  3. Place in water or soil.
  4. Keep moist and warm.

Best Time: Spring or early summer when the plant is actively growing.

Environment

Warm (70–75°F or 21–24°C), humid environment with indirect light.

Medium

Well-draining soil mix or water for cuttings; perlite or sand can improve drainage.

Hormone

Not necessary but can speed up rooting.

Timeline

Roots develop in 1–3 weeks; new growth appears in 4–6 weeks.

Tools Needed

Pruning shears, rooting hormone (optional), small pots, water or soil medium.

Quick Tips

Use clean tools to prevent disease; change water regularly if using water propagation; maintain consistent humidity.

Pruning & Repotting

Pruning Guide
Method

Pinch back tips to encourage branching; trim stems just above a leaf node.

Pruning Plan

Light pruning to maintain shape and encourage bushier growth; remove dead or damaged stems.

Tools

Pruning shears, sharp scissors, gloves.

Checklist

Use clean tools; prune dead or diseased parts; shape the plant as desired; dispose of clippings properly.

Repotting Guide
Best Season

Spring, before the active growing season begins.

Pot Size

One size larger pot (e.g., +2 inches in diameter); ensure good drainage.

Method

Remove plant gently; trim any circling roots; place in a slightly larger pot with fresh soil; water thoroughly.

Suggestions

Repot every 1–2 years or when roots fill the pot; beneficial for root health and growth.

Checklist

Choose 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; ensure drainage; avoid wetting foliage.

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 early in the morning to minimize evaporation and fungal growth.

Pro Tip: Use a soaker hose or drip irrigation to deliver water directly to the roots, reducing waste and fungal risk.
Watering Schedule Tips

Water deeply once the top inch of soil is dry; reduce frequency in winter to prevent root rot.

Soil Improvement

Add perlite or sand for drainage; incorporate compost for fertility; ensure soil is loose and airy.

Temperature Stress Management
Signs of Temperature Issues

Chlorosis (yellowing leaves) in cold; wilting or stunted growth in extreme heat.

Cold Stress

Low temperatures slow growth and can cause root damage or death; may enter dormancy.

Solution: Move potted plants indoors or to a protected area; use row covers for outdoor plants; avoid overwatering in cold conditions.

Hot Stress

Excessive heat can lead to wilting, leaf scorch, or reduced flowering; may require increased watering.

Solution: Provide shade during peak heat; increase watering frequency; use mulch to retain soil moisture.

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 every 4–6 weeks during growing season (spring/summer); avoid fertilizing in winter.

Common Problems & Solutions

Yellowing of leaves in Conyza canadensis can indicate nutrient deficiencies, water stress, or pathogen infection, often affecting photosynthetic efficiency and overall plant vigor.

Wilting in Conyza canadensis typically results from water stress, root damage, or pathogenic infections, leading to reduced turgor pressure and impaired nutrient uptake.

Leaf spots on Conyza canadensis are commonly caused by fungal or bacterial pathogens, resulting in reduced photosynthetic area and potential defoliation.

Rotting in Conyza canadensis is often caused by fungal or bacterial pathogens, particularly in moist conditions, leading to tissue degradation and potential plant death.

Toxicity Warning

Cats
Slightly Toxic

Cats are susceptible to liver toxicity from pyrrolizidine alkaloids found in Conyza canadensis, especially if they ingest the seeds or flowers. The effects can be cumulative and lead to chronic liver disease.

⚠️ Symptoms:
vomiting anorexia jaundice liver failure
🌿 Toxic Parts:
seeds flowers
⚡ Toxic If:

if eaten

Prevent cats from accessing this plant. Seek veterinary care immediately if ingestion is suspected.
Dogs
Slightly Toxic

Dogs may experience gastrointestinal distress and potential liver toxicity if they consume significant quantities of Conyza canadensis, particularly the seeds and flowers which contain pyrrolizidine alkaloids.

⚠️ Symptoms:
vomiting diarrhea lethargy liver dysfunction
🌿 Toxic Parts:
seeds flowers
⚡ Toxic If:

if eaten

Keep pets away from areas where this plant is present. Monitor for symptoms if ingestion is suspected.
Humans
Slightly Toxic

Conyza canadensis, commonly known as horseweed or Canadian fleabane, contains pyrrolizidine alkaloids that can cause liver damage upon ingestion. These compounds are particularly concentrated in the seeds and flowers.

⚠️ Symptoms:
nausea vomiting abdominal pain liver damage
🌿 Toxic Parts:
seeds flowers
⚡ Toxic If:

if eaten

Avoid ingestion of seeds and flowers. Handle with care, especially in agricultural settings.
Important: Keep this plant out of reach of children and pets. If ingestion occurs, contact poison control or veterinary services immediately.
Quick Reference
Family: N/A
Care: N/A
Light: full sun
Water: every 7–10 days during activ
Suitable For: Everyone
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