Black Yarrow
achillea atrata
Also known as: ["Alpine Yarrow","Black Milfoil"]
Overview
A hardy perennial herbaceous plant native to alpine regions, known for its feathery foliage and clusters of small, dark-colored flowers.
Benefits & Perks
["long-flowering","drought tolerant","wildlife attractant (bees, butterflies, birds)"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Achillea |
| Botanical Name: | Achillea atrata |
Plant Characteristics
Basic Information
- Category: Flowers
- Suitable Location: rock gardens, alpine troughs, or sunny borders
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"–15–30°C"}
- Hardiness: {"zones":"4–8"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Fast-draining to prevent root rot.
- Soil Type: Well-draining, sandy loam with some organic matter.
Maintenance Level
- Maintenance Level: low
- Toughness Level: high
- Pruning Frequency: After flowering; lightly trim throughout the growing season as needed.
- Pruning Intensity: Light to moderate; avoid heavy pruning unless rejuvenating an older plant.
Care Details
Ideal Sunlight Coverage:
Full sun (6–8 hours/day) with tolerance for partial shade in hot climates.
Sunlight Tolerance Tips:
Acclimate gradually to intense sunlight; protect from harsh afternoon sun in hot regions; ensure adequate light indoors with supplemental grow lights if needed.
Care Requirements
Care Difficulty
easymoderate
Sunlight
full sun
Rotate plant for even light exposure; provide shade during peak summer heat; monitor for sunburn signs.
Watering
every 7–10 days during active growth, less frequently in winter
Water at the base to avoid foliage wetting; ensure good drainage; adjust frequency based on weather and soil moisture.
Soil
well-drained, sandy or loamy soil
pH: Slightly acidic to neutral (pH 6.0–7.0).
Avoid heavy clay soils; ensure pots have drainage holes; amend with organic matter for better structure.
Temperature
Prefers cool to moderate temperatures (60–75°F or 15–24°C); tolerates cold but avoid extreme heat.
Avoid sudden temperature fluctuations; protect from frost; ensure good air circulation.
Fertilizing
every 4–6 weeks during spring and summer
Apply fertilizer to moist soil to prevent root burn; stop fertilizing before flowering to encourage blooms; flush soil occasionally to prevent salt buildup.
Propagation
Methods
Stem cuttings or division of clumps.
Step-by-Step Propagation Guide
- Take 4–6 inch cuttings.
- Remove lower leaves.
- Dip in rooting hormone.
- Plant in medium.
- Maintain humidity.
- Transplant when rooted.
Best Time: Early spring or late summer when plant is actively growing.
Environment
Warm (65–75°F or 18–24°C), high humidity (70–80%), and indirect light.
Medium
Well-draining mix of perlite and peat moss or cactus potting mix.
Hormone
Optional but recommended for faster rooting.
Timeline
Roots develop in 3–6 weeks; establish in new pot within 2–3 months.
Tools Needed
Pruning shears, rooting hormone, small pots, misting spray bottle.
Quick Tips
Use healthy, non-flowering stems; maintain consistent moisture; provide bottom heat for faster rooting.
Pruning & Repotting
Pruning Guide
Method
Deadhead by cutting above a leaf node; trim stems to encourage bushier growth.
Pruning Plan
Remove spent flowers to encourage reblooming; trim leggy growth to maintain shape.
Tools
Sharp pruning shears, gloves.
Checklist
Clean tools; deadhead regularly; trim leggy stems; remove damaged growth.
Repotting Guide
Best Season
Early spring before new growth begins.
Pot Size
One size up (e.g., from 4-inch to 6-inch pot); ensure good drainage holes.
Method
Remove plant gently; trim roots if crowded; repot in fresh, well-draining soil with a slightly larger pot.
Suggestions
Repot every 2–3 years or when roots fill the pot; beneficial for rejuvenation and growth.
Checklist
Choose appropriate pot; prepare fresh soil; trim roots if needed; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture before watering; water deeply; ensure drainage; adjust for season.
How to Apply Water Properly
Water thoroughly until it drains from the bottom, ensuring the root zone is moistened. Avoid overhead watering to minimize fungal issues.
Watering Schedule Tips
Water deeply but infrequently, allowing soil to dry between waterings. Reduce frequency in winter to prevent root rot.
Soil Improvement
Add perlite or coarse sand for drainage; incorporate compost for fertility; ensure soil is loose and airy.
Temperature Stress Management
Signs of Temperature Issues
Wilting, leaf scorch, stunted growth, or premature flowering in excessive heat; leaf drop or root rot in cold stress.
Cold Stress
Slows growth, may cause root damage if soil freezes; reduces flowering.
Solution: Insulate roots with mulch; avoid overwatering in cold; move potted plants to sheltered locations.
Hot Stress
Leaves may scorch, growth may stall, and water demand increases.
Solution: Provide afternoon shade; 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 every 4–6 weeks during growing season (spring to early summer); avoid fertilizing in winter.
Common Problems & Solutions
Toxicity Warning
Cats
Non-toxicAchillea atrata is not considered toxic to cats. The plant is generally safe, though large amounts may cause mild digestive disturbances due to its natural compounds.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if ingested
Dogs
Non-toxicAchillea atrata is not considered toxic to dogs. The plant contains compounds that are generally safe, though excessive consumption may lead to mild gastrointestinal upset.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if ingested
Humans
Non-toxicAchillea atrata is generally considered non-toxic to humans. However, ingestion of large quantities may cause mild gastrointestinal discomfort due to its essential oils and secondary metabolites.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten in large quantities
Frequently Asked Questions
Q: Is Achillea atrata suitable for rock gardens?
A: Yes, it thrives in rocky, well-drained soils typical of alpine environments.
Q: Does Achillea atrata attract pollinators?
A: Yes, its flowers are highly attractive to bees, butterflies, and other pollinators.
Q: How often should Achillea atrata be watered?
A: It is drought-tolerant and requires minimal watering, especially once established.
Quick Reference
| Family: | Asteraceae |
| Care: | easy |
| Light: | full sun |
| Water: | every 7–10 days during activ |
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