Wavy-leaved Thistle
cirsium undulatum
Also known as: ["Wavy-leaved Thistle","Wavyleaf Thistle"]
Overview
A herbaceous perennial thistle native to North America, known for its spiny leaves and purple flowers.
Benefits & Perks
["wildlife attractant (bees, butterflies, birds)","drought tolerant","aesthetic foliage"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Cirsium |
| Botanical Name: | Cirsium undulatum |
Plant Characteristics
Basic Information
- Category: Herbs & Weeds
- Suitable Location: open fields, meadows, or garden borders with good sunlight
- Suitable For:
- Is Weed: No
- Allergenicity: moderate
Environmental Needs
- Climate: {"temperatureRange":"–30 to 40°C"}
- Hardiness: {"zones":"3–9"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Fast-draining to prevent root rot.
- Soil Type: Well-draining, loamy soil with some organic matter; can tolerate poor soils.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: moderate
- Pruning Frequency: As needed, typically after flowering or in early spring.
- Pruning Intensity: Light to moderate; avoid heavy pruning unless necessary.
Care Details
Ideal Sunlight Coverage:
Full sun (6–8 hours/day); tolerates partial shade but may produce fewer flowers.
Sunlight Tolerance Tips:
Acclimate plants gradually to intense sunlight; protect from harsh afternoon sun in hot climates; ensure good air circulation to prevent fungal issues.
Care Requirements
Care Difficulty
moderatemoderate
Sunlight
full sun to partial shade
Rotate plant for even light exposure; use shade cloth in extreme heat; avoid direct sun on leaves during peak hours.
Watering
every 7–10 days during active growth, less frequently in winter
Water thoroughly but infrequently; ensure soil dries between waterings; avoid overhead watering.
Soil
well-drained, sandy or loamy soil
pH: Slightly acidic to neutral (pH 6.0–7.0).
Avoid heavy clay soils; use raised beds for better drainage; amend with organic matter for nutrients.
Temperature
Prefers moderate temperatures (60–75°F/15–24°C); can tolerate cooler nights and warmer days.
Avoid sudden temperature changes; protect from drafts; maintain consistent temperatures.
Fertilizing
every 2–3 months during growing season, none in winter
Apply fertilizer to moist soil; avoid contact with leaves; flush soil occasionally to prevent salt buildup.
Propagation
Methods
Stem cuttings or division; seeds can also be used but may take longer to establish.
Step-by-Step Propagation Guide
- Take a healthy cutting.
- Remove lower leaves.
- Dip in rooting hormone (optional).
- Plant in medium.
- Keep moist and warm.
Best Time: Spring or early summer when the plant is actively growing.
Environment
Warm, humid environment with indirect light; maintain consistent moisture.
Medium
Well-draining potting mix with perlite or sand; can also root in water.
Hormone
Rooting hormone is optional but recommended for faster rooting.
Timeline
Roots may develop in 2–4 weeks; new growth may appear in 6–8 weeks.
Tools Needed
Pruning shears, rooting hormone, small pots, well-draining soil mix.
Quick Tips
Use sharp, clean tools; keep cuttings out of direct sun; maintain humidity around cuttings.
Pruning & Repotting
Pruning Guide
Method
Cut stems just above a leaf node or bud; remove spent flowers to encourage reblooming.
Pruning Plan
Remove dead or damaged stems to encourage new growth; shape the plant as needed.
Tools
Pruning shears, gloves, disinfectant for tools.
Checklist
Clean tools; identify dead/damaged stems; cut at the right angle; dispose of clippings properly.
Repotting Guide
Best Season
Spring, before the active growing season begins.
Pot Size
Choose a pot one size larger than the current one; ensure good drainage.
Method
Remove plant gently; trim any circling roots; place in a new pot with fresh soil; water lightly.
Suggestions
Repot every 2–3 years or when roots fill the pot; beneficial for root health and growth.
Checklist
Select appropriate pot; prepare new soil mix; handle roots carefully; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture; 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 in the morning to reduce evaporation.
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 good aeration.
Temperature Stress Management
Signs of Temperature Issues
Wilting, yellowing leaves, or stunted growth in extreme heat or cold.
Cold Stress
Slows growth; may cause leaf damage or dieback in prolonged cold.
Solution: Provide frost protection; move potted plants indoors; use mulch to insulate roots.
Hot Stress
Leaves may wilt, scorch, or drop; flowering may be reduced.
Solution: Provide shade during peak heat; increase watering; use mulch to retain soil moisture.
Fertilizing Guide
Fertilizing Checklist
Check fertilizer type; dilute correctly; apply during active growth; avoid winter feeding.
Fertilizing Method
Use a balanced, water-soluble fertilizer diluted to half strength; fertilize every 4–6 weeks during growing season; avoid fertilizing in winter.
Common Problems & Solutions
Toxicity Warning
Cats
Slightly ToxicCirsium undulatum can cause mild gastrointestinal upset in cats if ingested. The sesquiterpene lactones present in the plant may lead to mild irritation or allergic reactions.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
Slightly ToxicIngestion of Cirsium undulatum can lead to mild gastrointestinal upset in dogs due to the presence of sesquiterpene lactones. The plant's spines may also cause physical injury if ingested.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
Slightly ToxicCirsium undulatum, commonly known as wavyleaf thistle, contains sesquiterpene lactones which can cause mild gastrointestinal distress and allergic reactions in some individuals. The plant's spiny nature may also cause physical injury upon contact.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Is Cirsium undulatum toxic to pets?
A: There is no reliable information available regarding its toxicity to pets.
Q: How do I care for Wavy-leaved Thistle?
A: It requires moderate care, including well-drained soil and full sun, and is drought-tolerant once established.
Q: Does this plant attract wildlife?
A: Yes, it attracts bees, butterflies, and birds, making it a good choice for wildlife gardens.
Quick Reference
| Family: | Asteraceae |
| Care: | moderate |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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