Sea Holly
eryngium spinalba
Also known as: ["Blue Sea Holly","Spiny Sea Holly"]
Overview
A striking perennial herbaceous plant with spiny, silvery-blue foliage and thistle-like flowers, native to Mediterranean regions.
Benefits & Perks
["long-flowering","deer resistant","wildlife attractant (bees, butterflies, birds)","drought tolerant","aesthetic foliage"]
Botanical Classification
| Phylum: | Magnoliophyta |
| Class: | Magnoliopsida |
| Order: | Apiales |
| Family: | Apiaceae |
| Genus: | Eryngium |
| Botanical Name: | Eryngium spinalba |
Plant Characteristics
Basic Information
- Category: Flowers
- Suitable Location: border plantings or rock gardens in temperate climates
- Suitable For:
- Is Weed: No
- Allergenicity: low
Environmental Needs
- Climate: {"temperatureRange":"5–35°C"}
- Hardiness: {"zones":"6–9"}
- Misting: rarely required, only if ambient humidity is very low
- Drainage: Fast-draining to prevent waterlogging.
- Soil Type: Well-draining, sandy loam with some organic matter; cactus or succulent mix works well.
Maintenance Level
- Maintenance Level: low
- Toughness Level: high
- Pruning Frequency: After flowering; light pruning can be done as needed throughout the growing season.
- Pruning Intensity: Light to moderate; avoid heavy pruning unless necessary to control size.
Care Details
Ideal Sunlight Coverage:
Full sun (6–8 hours of direct sunlight daily); tolerates partial shade in hot climates.
Sunlight Tolerance Tips:
Acclimate plants gradually to intense sunlight; protect from harsh afternoon sun in hot regions; ensure good air circulation to prevent fungal issues.
Care Requirements
Care Difficulty
easymoderate
Sunlight
full sun to partial shade
Rotate plant for even growth; provide shade during extreme heat; avoid direct sun on leaves during peak hours.
Watering
every 7–10 days during active growth, reduce in winter
Water thoroughly but infrequently; ensure soil dries between waterings; avoid overhead watering.
Soil
well-draining, sandy loam with moderate organic matter
pH: Slightly acidic to neutral (pH 6.0–7.0).
Avoid heavy clay soils; ensure pots have drainage holes; topdress with compost annually.
Temperature
Prefers temperate conditions (60–75°F or 15–24°C); can tolerate cooler nights but avoid frost.
Avoid sudden temperature changes; protect from drafts; maintain consistent temperatures for optimal growth.
Fertilizing
every 4–6 weeks during spring and summer
Apply fertilizer to moist soil to prevent root burn; flush soil occasionally to prevent salt buildup; reduce feeding in dormant periods.
Propagation
Methods
Stem cuttings or division; stem cuttings are more common for home growers.
Step-by-Step Propagation Guide
- Take a 4–6 inch cutting.
- Remove lower leaves.
- Apply rooting hormone.
- Plant in medium.
- Maintain humidity.
Best Time: Late spring to early summer when the plant is actively growing.
Environment
Warm (70–75°F or 21–24°C), humid environment with 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 develop in 3–6 weeks; new growth may take an additional 2–3 months.
Tools Needed
Pruning shears, rooting hormone, small pots, well-draining mix, plastic bags or propagator.
Quick Tips
Use healthy, non-flowering stems; keep soil consistently moist; provide bottom heat for faster rooting.
Pruning & Repotting
Pruning Guide
Method
Deadhead spent flowers; trim back leggy stems to a healthy bud or leaf node.
Pruning Plan
Remove spent flower heads to encourage reblooming; trim leggy growth to maintain shape.
Tools
Pruning shears, clean scissors, gloves.
Checklist
Sterilize tools; prune dead or damaged growth; remove spent flowers; shape as needed.
Repotting Guide
Best Season
Early spring before new growth begins.
Pot Size
One size larger pot (e.g., +2 inches in diameter); ensure good drainage.
Method
Remove plant gently; trim roots if crowded; place in a slightly larger pot with fresh soil; water lightly.
Suggestions
Repot every 2–3 years or when roots fill the pot; beneficial for container-grown plants.
Checklist
Choose appropriate pot size; prepare fresh soil mix; handle roots carefully; water after repotting.
Advanced Care Tips
Watering Mastery
Watering Checklist
Check soil moisture; water deeply; ensure drainage; adjust for season.
How to Apply Water Properly
Water at the base of the plant, ensuring moisture reaches the root zone; allow excess water to drain away; water early in the morning to minimize evaporation.
Watering Schedule Tips
Water deeply once the top inch of soil feels dry; reduce frequency in winter to prevent root rot.
Soil Improvement
Add perlite or coarse sand for drainage; incorporate compost for fertility; ensure good aeration.
Temperature Stress Management
Signs of Temperature Issues
Wilting, yellowing leaves, stunted growth, or browning leaf edges.
Cold Stress
Slows growth, may cause leaf drop, and can lead to root damage if temperatures drop below freezing.
Solution: Provide frost protection in winter; move potted plants indoors; use mulch to insulate roots.
Hot Stress
Leaves may scorch, wilt, or drop; growth may slow due to excessive heat.
Solution: Provide partial shade during peak heat; 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 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-toxicEryngium spinalba is not known to be toxic to cats. The plant does not produce compounds that are harmful to felines when ingested.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Dogs
Non-toxicEryngium spinalba is not known to be toxic to dogs. The plant does not produce compounds that are harmful to canines when ingested.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Humans
Non-toxicEryngium spinalba is not known to exhibit toxic properties in humans. The plant is generally considered safe for consumption, though it is not commonly used as a food source.
🌿 Toxic Parts:
⚡ Toxic If:
if eaten
Frequently Asked Questions
Q: How do I propagate Eryngium spinalba?
A: Propagate by seed in spring or by division in early autumn.
Q: Does Sea Holly attract pollinators?
A: Yes, it is highly attractive to bees, butterflies, and other pollinators.
Q: Is Sea Holly suitable for dry gardens?
A: Yes, it is drought-tolerant and thrives in well-drained, dry soils.
Quick Reference
| Family: | Apiaceae |
| Care: | easy |
| Light: | full sun to partial shade |
| Water: | every 7–10 days during activ |
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