Oriental spirea
spiraea thunbergii
Also known as: ["Thunberg's spirea","Willowleaf spirea"]
Overview
A deciduous shrub with delicate, willow-like leaves and early spring flowers.
Benefits & Perks
["long-flowering","wildlife attractant (bees, butterflies, birds)","aesthetic foliage"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Rosales |
| Family: | Rosaceae |
| Genus: | Spiraea |
| Botanical Name: | Spiraea thunbergii |
Plant Characteristics
Basic Information
- Category: Shrubs
- Suitable Location: garden border or mixed shrubbery, in a location with good air circulation
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"–10–35°C"}
- Hardiness: {"zones":"5–8"}
- 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 organic matter; can tolerate average garden soil.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: moderate
- Pruning Frequency: Annually, immediately after flowering; light maintenance pruning can be done as needed.
- Pruning Intensity: Moderate; remove up to one-third of old growth if needed to rejuvenate the plant.
Care Details
Ideal Sunlight Coverage:
Full sun to partial shade (4–6 hours of direct sunlight daily); tolerates light shade in hot climates.
Sunlight Tolerance Tips:
Acclimate new plants to sunlight gradually; protect from intense midday sun in summer; place in a spot with morning sun and afternoon shade if needed.
Care Requirements
Care Difficulty
easymoderate
Sunlight
full sun to partial shade
Monitor for leaf scorch; adjust placement based on seasonal light intensity; ensure adequate light for blooming.
Watering
every 7–10 days during active growth, less frequently in winter
Water thoroughly until runoff; allow soil to dry slightly between waterings; avoid frequent shallow watering.
Soil
well-drained, loamy soil with moderate organic content
pH: Slightly acidic to neutral (pH 6.0–7.0).
Ensure soil is not compacted; maintain consistent moisture; avoid heavy clay soils unless amended.
Temperature
Hardy in USDA zones 5–8; prefers temperatures between 60–75°F (15–24°C); tolerates winter cold down to -20°F (-29°C).
Protect from late spring frosts; ensure good air circulation in hot weather; adjust watering based on temperature fluctuations.
Fertilizing
every 4–6 weeks during spring and summer
Fertilize lightly after pruning; avoid over-fertilizing to prevent leaf burn; stop fertilizing in autumn to prepare for dormancy.
Propagation
Methods
Softwood cuttings in late spring or early summer; layering can also be successful.
Step-by-Step Propagation Guide
- Take 4–6 inch cuttings.
- Remove lower leaves.
- Dip in rooting hormone.
- Plant in medium.
- Keep moist and humid.
Best Time: Late spring to early summer when new growth is flexible and actively growing.
Environment
High humidity (70–90%), warm temperatures (65–75°F), and indirect light.
Medium
Well-draining potting mix with perlite or sand; can also root in water initially.
Hormone
Rooting hormone is recommended to improve success rates.
Timeline
Roots typically form in 4–8 weeks; establish in new pot after 3–6 months.
Tools Needed
Pruning shears, rooting hormone, small pots, misting spray bottle, plastic bags for humidity.
Quick Tips
Keep cuttings out of direct sun; maintain consistent moisture; check for roots after 3 weeks.
Pruning & Repotting
Pruning Guide
Method
Selective thinning of branches; heading back to encourage denser growth; remove crossing or damaged stems.
Pruning Plan
Prune to maintain shape, encourage bushiness, and remove dead or weak growth; best done after flowering to avoid cutting off next year's buds.
Tools
Hand pruners, loppers (for larger branches), pruning saw (if necessary), disinfectant for tools.
Checklist
Prune after flowering; sterilize tools; make clean cuts; remove dead or diseased wood; shape as desired.
Repotting Guide
Best Season
Early spring before new growth begins; avoid repotting during flowering or dormancy.
Pot Size
Increase pot size by 2–3 inches in diameter; ensure good drainage holes.
Method
Remove plant gently; trim any circling roots; place in a slightly larger pot with fresh soil; water thoroughly after repotting.
Suggestions
Repot every 2–3 years or when roots fill the container; beneficial for container-grown plants to refresh soil and space.
Checklist
Choose appropriate pot size; use fresh soil mix; trim roots if crowded; water well after repotting; place in shade for a few days.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture before watering; water deeply; ensure proper drainage; adjust frequency seasonally.
How to Apply Water Properly
Water at the base of the plant, ensuring moisture reaches the root zone; water early in the morning to minimize evaporation; ensure excess water drains away to prevent root rot.
Watering Schedule Tips
Water deeply once a week during spring and summer; reduce frequency to every 2–3 weeks in fall and winter; adjust based on rainfall and soil moisture.
Soil Improvement
Add compost or well-rotted manure to enhance fertility and structure; mix in perlite or sand for better drainage.
Temperature Stress Management
Signs of Temperature Issues
Leaf scorch or wilting in excessive heat; delayed bud break or leaf drop in cold stress.
Cold Stress
Leaves may become discolored or drop; buds may fail to open; growth may slow or stop in prolonged cold.
Solution: Mulch around the base to insulate roots; protect from harsh winter winds; avoid overwatering in cold weather.
Hot Stress
Wilting, leaf scorch, or reduced flowering; may drop leaves to conserve water.
Solution: Provide shade during peak heat; water deeply and mulch to retain moisture; avoid fertilizing during extreme heat.
Fertilizing Guide
Fertilizing Checklist
Use balanced fertilizer; apply in early spring; avoid late-season feeding; follow package instructions.
Fertilizing Method
Use a balanced, slow-release fertilizer in early spring; dilute liquid fertilizer to half-strength if used monthly during growing season; avoid fertilizing in late fall or winter.
Common Problems & Solutions
Toxicity Warning
Cats
Non-toxicSpiraea thunbergii is not considered toxic to cats. There are no known adverse effects from ingestion or contact with this plant.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
Non-toxicSpiraea thunbergii is not considered toxic to dogs. There are no known adverse effects from ingestion or contact with this plant.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
Non-toxicSpiraea thunbergii is generally considered non-toxic to humans. There are no significant toxic effects or physiological impacts reported from ingestion or contact.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Does Spiraea thunbergii attract wildlife?
A: Yes, it attracts bees, butterflies, and birds with its flowers.
Q: Is Spiraea thunbergii toxic to pets?
A: No, it is non-toxic to dogs and cats.
Q: When does Spiraea thunbergii bloom?
A: It blooms in early spring, typically March to April.
Quick Reference
| Family: | Rosaceae |
| Care: | easy |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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