European Alder
alnus glutinosa
Also known as: ["Black Alder","Common Alder","European Black Alder"]
Overview
A deciduous tree native to Europe, known for its tolerance to waterlogged soils and nitrogen-fixing capabilities.
Benefits & Perks
["disease resistant","wildlife attractant (bees, butterflies, birds)","drought tolerant","shade tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Fagales |
| Family: | Betulaceae |
| Genus: | Alnus |
| Botanical Name: | Alnus glutinosa |
Plant Characteristics
Basic Information
- Category: Trees
- Suitable Location: near water bodies or in damp garden areas
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"–30–40°C"}
- Hardiness: {"zones":"3–7"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Moderate to slow-draining; can tolerate waterlogged conditions but prefers well-aerated soil.
- Soil Type: Rich, loamy soil with good organic matter content; tolerates wet, clay soils better than many trees.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: high
- Pruning Frequency: Annually in late winter or early spring before new growth begins.
- Pruning Intensity: Moderate; remove up to one-third of old growth if necessary, but avoid heavy pruning on young trees.
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
moderatemoderate
Sunlight
partial shade to full sun
Monitor leaf color for sun stress, provide shade during peak heat, rotate plant for even light exposure.
Watering
every 7–10 days, more frequently in dry conditions
Water thoroughly until drainage occurs; allow soil to dry slightly between waterings; avoid overwatering.
Soil
moist, fertile, well-drained loam
pH: Acidic to neutral (pH 5.5–7.0).
Ensure soil is consistently moist but not waterlogged, amend with organic matter for fertility, check pH periodically.
Temperature
Hardy in USDA zones 3–7; tolerates cold temperatures down to -30°F (-34°C); prefers cool to moderate temperatures.
Protect from frost in early spring, avoid sudden temperature fluctuations, maintain consistent cool temperatures for best growth.
Fertilizing
annually in early spring with a balanced slow-release fertilizer
Fertilize only when actively growing, avoid over-fertilization which can harm roots, water well after applying fertilizer.
Propagation
Methods
Softwood cuttings in early summer or seed propagation in autumn.
Step-by-Step Propagation Guide
- Select healthy cuttings, apply rooting hormone, plant in medium, maintain humidity, and provide warmth.
- For seeds, stratify if necessary, sow, and keep moist.
Best Time: Early summer for cuttings; autumn for seeds after the plant has set fruit.
Environment
High humidity, indirect light, and consistent warmth (65–75°F or 18–24°C) for cuttings; cooler temperatures for seed germination.
Medium
Peat and perlite mix or sandy loam for cuttings; well-drained seed starting mix for seeds.
Hormone
Rooting hormone is recommended for cuttings to improve success rates.
Timeline
Cuttings may root in 4–8 weeks; seeds can take several months to germinate and establish.
Tools Needed
Pruning shears, rooting hormone, propagation tray, humidity dome, heat mat.
Quick Tips
Use sharp, sterile tools for cuttings, maintain consistent moisture, avoid direct sunlight during rooting.
Pruning & Repotting
Pruning Guide
Method
Thinning cuts to remove entire branches back to the trunk or main branch; heading cuts to shorten branches and encourage bushiness.
Pruning Plan
Prune to maintain shape, remove dead or diseased wood, and encourage healthy growth; focus on structural improvement.
Tools
Pruning shears, loppers, saw for larger branches, sterilizing solution.
Checklist
Sterilize tools, prune during dormancy, remove dead/diseased wood, make clean cuts, avoid over-pruning.
Repotting Guide
Best Season
Early spring before active growth begins.
Pot Size
Increase pot size by 2–3 inches in diameter; ensure the new pot has adequate drainage holes.
Method
Remove the plant gently, trim any circling roots, place in a slightly larger pot with fresh soil, water thoroughly, and avoid fertilizing for a month.
Suggestions
Repot only if the plant is root-bound or the soil is depleted; typically every 2–3 years for container-grown specimens.
Checklist
Check root boundness, prepare new pot, trim roots if needed, use fresh soil, water well, avoid direct sun post-repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture, water deeply, ensure drainage, avoid wetting foliage, adjust for season.
How to Apply Water Properly
Water at the base of the plant, ensuring moisture reaches the root zone; water early in the day to minimize evaporation; ensure proper drainage to prevent waterlogging.
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 well-rotted manure to enhance fertility and structure; incorporate sand or perlite if soil is too heavy.
Temperature Stress Management
Signs of Temperature Issues
Leaf scorch in excessive heat, leaf drop or dieback in prolonged cold without protection, stunted growth in temperature extremes.
Cold Stress
Leaves may turn yellow or brown, branches can die back, and overall growth may slow or cease in extreme cold.
Solution: Mulch heavily around the base, wrap trunks with burlap in severe cold, avoid planting in exposed, windy sites.
Hot Stress
Wilting, leaf scorch, reduced growth, and potential dieback due to excessive heat and dry conditions.
Solution: Provide shade during peak heat, increase watering frequency, use mulch to retain soil moisture, ensure good air circulation.
Fertilizing Guide
Fertilizing Checklist
Check growth stage, use appropriate fertilizer, apply at recommended rate, water thoroughly after application.
Fertilizing Method
Use a balanced, slow-release fertilizer in early spring; avoid high-nitrogen formulas; reduce or stop fertilizing in late summer to prepare for dormancy.
Common Problems & Solutions
Toxicity Warning
Cats
Non-toxicAlnus glutinosa is not considered toxic to cats. The plant does not contain any known toxic substances that would cause harm to felines if ingested or if the plant is handled.
⚡ Toxic If:
Generally non-toxic
Dogs
Non-toxicAlnus glutinosa is not considered toxic to dogs. There are no known toxic compounds in the plant that would pose a risk to canine health if ingested or if the plant is handled.
⚡ Toxic If:
Generally non-toxic
Humans
Non-toxicAlnus glutinosa, commonly known as European alder, is not considered toxic to humans under normal circumstances. The plant does not produce any known toxic compounds that would cause adverse effects upon ingestion or contact.
⚡ Toxic If:
Generally non-toxic
Frequently Asked Questions
Q: Is Alnus glutinosa suitable for wet soil conditions?
A: Yes, it is highly tolerant of waterlogged soils and thrives in such environments.
Q: Does this tree attract wildlife?
A: Yes, it supports pollinators like bees and butterflies, and provides habitat for birds.
Q: Is the European Alder toxic to pets?
A: No, it is non-toxic to dogs and cats.
Quick Reference
| Family: | Betulaceae |
| Care: | moderate |
| Light: | partial shade to full sun |
| Water: | every 7–10 days, more freque |
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