Rusty Blackhaw
viburnum rufidulum
Also known as: ["Blueberry Hibiscus","Rusty Hawthorn"]
Overview
A deciduous shrub or small tree native to eastern and central North America, known for its attractive white flowers, blue-black berries, and reddish-purple fall foliage.
Benefits & Perks
["long-flowering","wildlife attractant (bees, butterflies, birds)","shade tolerant"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Dipsacales |
| Family: | Adoxaceae |
| Genus: | Viburnum |
| Botanical Name: | Viburnum rufidulum |
Plant Characteristics
Basic Information
- Category: Shrubs
- Suitable Location: garden bed or container in a location with good air circulation
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"–15–35°C"}
- Hardiness: {"zones":"4–8"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Moderate to good drainage; avoid waterlogged conditions.
- Soil Type: Well-draining, loamy soil with organic matter. Tolerates clay but prefers amended soil.
Maintenance Level
- Maintenance Level: moderate
- Toughness Level: moderate
- Pruning Frequency: Annually after flowering; light shaping as needed throughout the growing season.
- Pruning Intensity: Light to moderate; avoid heavy pruning unless necessary for health or rejuvenation.
Care Details
Ideal Sunlight Coverage:
Full sun to partial shade (4–6 hours of direct sunlight daily). Tolerates light shade but may produce fewer flowers.
Sunlight Tolerance Tips:
Acclimate plants gradually to intense sunlight to prevent scorching; place in a location with morning sun and afternoon shade in hot climates; adjust indoor placement to mimic natural light conditions.
Care Requirements
Care Difficulty
moderatemoderate
Sunlight
full sun to partial shade
Avoid sudden light changes; protect from harsh afternoon sun in summer; rotate plants for even growth.
Watering
every 7–10 days during active growth, less frequently in winter
Water thoroughly but infrequently to encourage deep root growth; avoid overwatering, especially in winter; ensure soil dries slightly between waterings.
Soil
well-drained, loamy soil with moderate organic content
pH: Slightly acidic to neutral (pH 5.5–7.0).
Ensure good drainage; amend with organic matter; test pH periodically; avoid compacted soil.
Temperature
Hardy in USDA zones 4–8. Prefers temperatures between 60–75°F (15–24°C). Tolerates cold winters but benefits from protection in extreme heat.
Protect from late spring frosts; water deeply before cold snaps; avoid placing near heat sources in winter.
Fertilizing
every 4–6 weeks during spring and summer
Fertilize sparingly; avoid late-season feeding to prevent tender growth; water thoroughly after fertilizing.
Propagation
Methods
Softwood cuttings taken in late spring or early summer.
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: Late spring to early summer when new growth is firm but not woody.
Environment
High humidity (70–90%), warm temperatures (70–75°F), and bright indirect light.
Medium
Peat-based mix with perlite or sand for good drainage.
Hormone
Rooting hormone is recommended to improve success rates.
Timeline
Roots typically form in 4–8 weeks; establish in pots or ground within one growing season.
Tools Needed
Pruning shears, rooting hormone, propagation tray, humidity dome, misting spray bottle.
Quick Tips
Use clean tools; maintain consistent moisture; provide bottom heat if possible; avoid direct sunlight.
Pruning & Repotting
Pruning Guide
Method
Selective removal of branches; thinning out crowded areas; heading back to control size.
Pruning Plan
Prune to maintain shape, remove dead or diseased wood, and encourage flowering. Light pruning after flowering is ideal.
Tools
Pruning shears, loppers, saw (for larger branches), sterilizing solution.
Checklist
Sterilize tools; prune after flowering; remove dead/diseased wood; shape lightly; clean up debris.
Repotting Guide
Best Season
Early spring before new growth begins.
Pot Size
Increase pot size by 2–3 inches in diameter; ensure drainage holes are clear.
Method
Remove plant gently; trim roots if necessary; replace with fresh soil mix; ensure good drainage; water thoroughly.
Suggestions
Repot only when root-bound or soil is depleted. Typically every 2–3 years for container-grown plants.
Checklist
Choose appropriate pot size; prepare fresh soil mix; trim roots if needed; 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 at the base; ensure proper drainage; adjust frequency by season.
How to Apply Water Properly
Water at the base of the plant, targeting the root zone. Apply water slowly and deeply to allow penetration, ensuring excess drains away to prevent waterlogging. Water early in the morning to minimize evaporation.
Watering Schedule Tips
Water deeply once a week during spring and summer, reducing 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 improve structure and fertility; incorporate perlite or sand for drainage in heavy soils.
Temperature Stress Management
Signs of Temperature Issues
Chlorosis or leaf scorch in excessive heat; leaf drop or dieback in prolonged cold exposure.
Cold Stress
Leaves may wilt, turn brown, or drop. Young growth is particularly susceptible to frost damage.
Solution: Mulch heavily around the base in winter; protect with burlap screens in exposed locations; avoid planting in frost pockets.
Hot Stress
Leaves may wilt, scorch, or drop. Growth may slow, and flowering may be reduced.
Solution: Provide afternoon shade; increase watering during heatwaves; use mulch to retain soil moisture.
Fertilizing Guide
Fertilizing Checklist
Use balanced fertilizer; apply in early spring; avoid over-fertilization; water after application.
Fertilizing Method
Use a balanced, slow-release fertilizer in early spring. Apply a light application again after flowering. Avoid high-nitrogen fertilizers.
Common Problems & Solutions
Toxicity Warning
Cats
Slightly ToxicThe berries of Viburnum rufidulum can induce mild gastrointestinal symptoms in cats upon ingestion. The toxic compounds primarily affect the digestive tract, causing discomfort.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
Slightly ToxicThe berries of Viburnum rufidulum can cause mild gastrointestinal upset in dogs if ingested. The lectins and other compounds present may lead to irritation of the digestive system.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
Slightly ToxicThe berries of Viburnum rufidulum contain lectins and other compounds that can cause mild gastrointestinal distress when ingested in significant quantities. The physiological impact is generally limited to irritation of the digestive tract.
⚠️ Symptoms:
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: Does Viburnum rufidulum attract wildlife?
A: Yes, it attracts bees, butterflies, and birds with its flowers and berries.
Q: Is Viburnum rufidulum toxic to pets?
A: No, it is non-toxic to dogs and cats.
Q: What are the common problems with Viburnum rufidulum?
A: Common issues include leaf spots and fungal growth.
Quick Reference
| Family: | Adoxaceae |
| Care: | moderate |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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