Square-stemmed Willowherb
epilobium tetragonum
Also known as: ["Square-stemmed Fireweed","Square-stemmed Epilobium"]
Overview
A herbaceous perennial plant native to Europe and parts of Asia, characterized by its square stems and pinkish-purple flowers.
Benefits & Perks
["wildlife attractant (bees, butterflies, birds)","drought tolerant","shade tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Myrtales |
| Family: | Onagraceae |
| Genus: | Epilobium |
| Botanical Name: | Epilobium tetragonum |
Plant Characteristics
Basic Information
- Category: Herbs & Weeds
- Suitable Location: garden bed near water source or in moist meadow
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"5–30°C"}
- Hardiness: {"zones":"6–9"}
- 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 added organic matter; can tolerate slightly sandy or clay soils if amended.
Maintenance Level
- Maintenance Level: low
- Toughness Level: moderate
- Pruning Frequency: Light pruning can be done anytime; major pruning is best done in late winter or early spring before new growth begins.
- Pruning Intensity: Moderate; remove up to one-third of the plant if needed, but avoid excessive pruning in a single ses
Care Details
Ideal Sunlight Coverage:
Full sun to partial shade; 6–8 hours of direct sunlight per day, with some afternoon shade in hot climates.
Sunlight Tolerance Tips:
Acclimate gradually to intense sunlight; protect from harsh afternoon sun to prevent scorching; adjust placement based on indoor/outdoor conditions.
Care Requirements
Care Difficulty
easymoderate
Sunlight
full sun to partial shade
Rotate plant for even light exposure; use sheer curtains to filter intense sun; monitor for signs of sunburn.
Watering
every 7–10 days during active growth, reduce in winter
Water thoroughly until it drains from the bottom; allow soil to dry between waterings; avoid overwatering.
Soil
moist, fertile, well-drained loam
pH: Slightly acidic to neutral (pH 6.0–7.0).
Use a mix of garden soil and compost; ensure pots have drainage holes; avoid heavy clay soils unless amended.
Temperature
Prefers moderate temperatures between 60–75°F (15–24°C); tolerates cooler temperatures but avoids frost.
Avoid sudden temperature changes; protect from drafts; maintain consistent room temperature.
Fertilizing
every 4–6 weeks during growing season, none in winter
Fertilize only when actively growing; flush soil occasionally to prevent salt buildup; use a balanced formula for even nutrition.
Propagation
Methods
Stem cuttings or division; stem cuttings are the most common method for home growers.
Step-by-Step Propagation Guide
- Take a healthy cutting, apply rooting hormone if using, plant in medium, keep moist, and wait for roots to form.
Best Time: Spring or early summer when the plant is actively growing.
Environment
Warm, humid environment with indirect light; maintain consistent moisture without waterlogging.
Medium
Well-draining potting mix with perlite or sand; can also root in water initially.
Hormone
Rooting hormone is optional but recommended for faster and more reliable rooting.
Timeline
Roots typically develop in 2–4 weeks; new growth may take an additional 4–6 weeks.
Tools Needed
Pruning shears, rooting hormone, small pots, well-draining medium.
Quick Tips
Use healthy, non-flowering stems; keep cuttings out of direct sun; maintain humidity around cuttings.
Pruning & Repotting
Pruning Guide
Method
Use clean cuts just above a leaf node or bud; remove crossing or crowded branches to improve air circulation.
Pruning Plan
Prune to maintain shape, encourage bushier growth, and remove dead or diseased parts.
Tools
Pruning shears, sterilizing solution, gloves.
Checklist
Sterilize tools, prune dead/damaged growth, shape the plant, clean up debris, monitor for regrowth.
Repotting Guide
Best Season
Early spring before the growing season begins is ideal.
Pot Size
Choose a pot one size larger than the current one, with a diameter about 2–3 inches wider.
Method
Remove the plant gently, trim any circling roots, place in a new pot with fresh soil, and water thoroughly after repotting.
Suggestions
Repot every 2–3 years or when the plant becomes root-bound; beneficial for refreshing soil and encouraging growth.
Checklist
Select new pot, prepare fresh soil, inspect roots, position plant, water, and place in appropriate light.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture, water deeply, ensure drainage, adjust for season.
How to Apply Water Properly
Water directly at the root zone, ensuring even moisture distribution; water early in the day to minimize evaporation; ensure excess water drains away to prevent waterlogging.
Watering Schedule Tips
Water deeply once the top inch of soil is dry; reduce frequency in winter to prevent root rot.
Soil Improvement
Add compost or well-rotted manure for fertility; mix in perlite or sand to improve drainage; ensure good aeration by avoiding compacted soil.
Temperature Stress Management
Signs of Temperature Issues
Wilting, yellowing leaves, stunted growth, or bud drop in extreme heat or cold.
Cold Stress
Low temperatures slow growth and can cause leaf damage or dieback; frost can be lethal.
Solution: Protect from frost with a cover or move indoors; ensure good air circulation to prevent cold dampness.
Hot Stress
Excessive heat can lead to wilting, leaf scorch, or reduced flowering.
Solution: Provide shade during peak heat, increase humidity, and water more frequently to compensate for evaporation.
Fertilizing Guide
Fertilizing Checklist
Check growth phase, dilute fertilizer, apply to moist soil, avoid winter feeding.
Fertilizing Method
Use a balanced liquid fertilizer diluted to half strength every 4–6 weeks during the growing season (spring to early fall); avoid fertilizing in winter.
Common Problems & Solutions
Toxicity Warning
Cats
Non-toxicEpilobium tetragonum is not considered toxic to cats. It has no known toxic effects or physiological impact when ingested.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
Non-toxicEpilobium tetragonum is not considered toxic to dogs. It has no known toxic effects or physiological impact when ingested.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
Non-toxicEpilobium tetragonum is not considered toxic to humans. It has no known toxic effects or physiological impact when ingested.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Is Epilobium tetragonum toxic to pets?
A: No, it is non-toxic to dogs and cats.
Q: Does this plant attract wildlife?
A: Yes, it attracts bees, butterflies, and birds.
Q: Is it suitable for beginners?
A: Yes, it is easy to care for and requires low maintenance.
Quick Reference
| Family: | Onagraceae |
| Care: | easy |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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