The Story
Plant Bio
Eryngium yuccifolium, commonly known as the rattlesnake master, is a perennial with spiky, yucca-like foliage and distinctive, globe-shaped clusters of pale green to bluish flowers that attract pollinators.
The Kershaw Blue cultivar features striking, silvery-blue foliage and large, prominent flower heads that provide a dramatic architectural element in perennial borders.
Uses & Benefits:
Essentials
At a Glance
Plant Type
Perennial
Height
24 inches
Width
18 inches
Light
Full Sun
Zones
4, 5, 6, 7, 8, 9
Water
Low to moderate
Humidity
Low
Lifespan
Perennial
Native To
North America
Toxicity
Non-toxic
Bloom period
Mid-summer – Late summer
In flower about 2 months of the year
Planting
How to Grow
- Tuck seeds into well-draining soil in early spring.
- Water lightly until established, about 2 weeks.
- Place in full sun for best flowering.
- Avoid overwatering to prevent root rot.
- Fertilize lightly in spring with a balanced fertilizer.
- Divide every 3–4 years in early spring to maintain health.
Pro Tip
Ensure excellent drainage to prevent root rot and promote healthy growth.
Keep It Thriving
Care Guide
Do
- Water during prolonged dry periods 💧
- Apply a light layer of mulch to conserve moisture
- Prune dead or damaged foliage in early spring
Don't
- Overwater to avoid fungal issues ❌
- Use heavy clay soil without amendments
- Neglect pruning which keeps the plant tidy
Seasonal Care Calendar
| Task | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Harvest | ||||||||||||
| Plant | ||||||||||||
| Spring Cleanup |
Watch Out For
Pests & Diseases
Common Pests
Common Diseases
In the Garden
Landscape Uses & Companions
Landscape Uses
Multiply
Propagation Methods
Good to Know
Common Questions
Upland Sea Holly Kershaw Blue questions
What zones can Upland Sea Holly Kershaw Blue grow in?
Upland Sea Holly Kershaw Blue is hardy in USDA Zones 4–9. Inside that range it survives winter in the ground; outside it, grow it as an annual or a container plant you protect.
Is Upland Sea Holly Kershaw Blue deer resistant?
Not reliably. Deer may browse Upland Sea Holly Kershaw Blue, especially tender spring growth — plan on repellents or fencing where pressure is high.
When does Upland Sea Holly Kershaw Blue bloom?
Upland Sea Holly Kershaw Blue typically blooms in mid-summer through late summer. Exact timing shifts a week or two with your zone — Sow's bloom calendar maps it to your garden.
Does Upland Sea Holly Kershaw Blue need full sun?
Upland Sea Holly Kershaw Blue does best in full sun (6+ hours).
Is Upland Sea Holly Kershaw Blue drought tolerant?
Yes — once established (usually after the first full season), Upland Sea Holly Kershaw Blue handles dry spells with minimal watering. Water deeply its first year to build the root system that makes that possible.
More Eryngium to compare
Sea Holly
Eryngium elevatum
rattlesnake master
Eryngium yuccifolium
Big Blue Sea Holly
Eryngium x hybrida 'Big Blue'
Blue Glitter Sea Holly
Eryngium planum 'Blue Glitter'
Blue Hobbit Eryngium
Eryngium x zabelii 'Blue Hobbit'
Picos Blue Sea Holly
Eryngium bourgatii 'Picos Blue'
Keep exploring
Explore the genus
Grow Upland Sea Holly Kershaw Blue with confidence
See it in a design of your actual yard, get zone-matched care reminders, and track it season by season in your garden journal.