Rattlesnake master
Eryngium yuccifolium · Apiaceae
Greenish-white, golf-ball flower heads on tall, branching stems above a rosette of sword-shaped, blue-green leaves like a yucca. A tallgrass prairie native.
- Size
- 4 ft tall, 24 in wide
- Zones
- 3 to 8
- Light
- Full sun
- Flowers
- Mid July to late August
- Pets
- No toxicity recorded
- Job in a bed
- Accent
A bed built around rattlesnake master
The planner designed this bed around rattlesnake master when this page was made: a 12 × 6 ft (3.7 × 1.8 m) naturalistic planting in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why rattlesnake master stands where it does.
The plants
- 1 Rattlesnake master × 3, white
- 2 Yellow ice plant × 11, yellow
- 3 October daphne × 7, pink
- 4 Switchgrass 'Cheyenne Sky' × 3, purple
- 5 Silver sage × 1, silver leaves
- 6 European columbine × 6, blue
- 7 Hyacinth × 12, blue
- 8 Darwin hybrid tulip × 5, red
Why this plant
- The only globes. The others are daisies, dense clusters, airy sprays and others. Shape reads at a distance, where colours blur.
- The only white. White sits between stronger colours and calms them.
Why here
- Anchors a back corner. At 4 ft it is the tallest plant here, and the tallest close the ends of the bed, where they stand in front of nothing.
- A step in the back row. Next to European columbine (2½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one clump. A single spire is too slight to hold a place alone, so here the accent is a clump.
Why now
- In flower for 7 weeks. From mid July to late August.
- Fills a gap. For two of those weeks nothing else on the plan is in flower.
Planned as a naturalistic planting: low grasses and groundcovers, the matrix, make up 50% of the planted ground. Cool colours (pink, purple and blue) with yellow and red as the warm notes, and white to calm things between them. The bed is tied together by its repeats: two kinds come round again along it, yellow ice plant and October daphne.
The planner's own design check: 13 Excellent, 4 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where rattlesnake master goes in a border
At 4 ft it belongs at the back of a bed. In the planner's ten height classes it is moderately tall (3 to 4 ft). It is airy enough to see through, so it can also come forward and veil what is behind it.
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
Its round heads on bare stems read as a set of dots above the grasses, a shape nothing else in the prairie palette provides. Use single plants scattered through a matrix of little bluestem or prairie dropseed.
- A sculptural accent in prairie planting
- Winter seed heads
- Pollinator gardens
What to plant with rattlesnake master
Plants recorded as good partners for it, and what each pairing does:
- Little bluestem: its blue-green leaves are a setting for the flowers, before and after; fine leaves against its bold ones.
- Prairie dropseed: in flower together for two weeks, from mid August; fine leaves against its bold ones.
- Purple coneflower: in flower together for seven weeks, from mid July; medium leaves against its bold ones.
Questions about rattlesnake master
Does rattlesnake master need sun or shade?
Rattlesnake master grows in full sun (6 or more hours of direct sun a day).
It wants ordinary well-drained soil, of average fertility, and little watering once settled. Once settled in, it stands drought.
What zones does rattlesnake master grow in?
USDA zones 3 to 8. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).
Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does rattlesnake master flower in my zone?
In zone 5 it flowers mid July to late August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 3 | Mid July to late August |
|---|---|
| Zone 4 | Mid July to late August |
| Zone 5 | Mid July to late August |
| Zone 6 | Mid July to late August |
| Zone 7 | Early July to mid August |
| Zone 8 | Early July to mid August |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should rattlesnake master be planted?
18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.
It grows 4 ft (120 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many rattlesnake master plants do I need?
At 18 in apart, set out in staggered rows:
- 5 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 17 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.
In the bed above, the planner used three in one group.
Is rattlesnake master poisonous to dogs and cats?
No toxicity is recorded for dogs, cats, horses or people, according to NC State Extension.
"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.
Do deer eat rattlesnake master?
Mostly not. NC State lists it as resistant to deer and rabbits. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.
What flowers after rattlesnake master?
Rattlesnake master is over by late August. These start as it finishes and carry the same spot on, so it never goes flat:
- Prairie dropseed: from mid August to mid September, 2½ ft tall, to stand in front of it and cover its fading stems (a recorded partner).
- Garden chrysanthemum: from mid September to late October, 24 in tall, to stand in front of it and cover its fading stems.
- Sedum 'Autumn Joy': from mid August to mid October, 24 in tall, to stand in front of it and cover its fading stems.
What does rattlesnake master look like in winter?
Rattlesnake master dies down, but leave the stems standing: the seed heads stand through the winter. Cut them down in early spring, before the new shoots come.
Is rattlesnake master good for bees and butterflies?
Rattlesnake master is visited by pollinators, bees, butterflies and moths.
It is a host plant: the caterpillars of rattlesnake-master borer feed on its leaves. A butterfly can only lay its eggs on its host plants, so these do more for it than any nectar flower.
It is native to the United States.
More Eryngium
- Alpine sea holly Eryngium alpinum
- Mediterranean sea holly Eryngium bourgatii
- Miss Willmott's ghost Eryngium giganteum
- Sea holly Eryngium planum
- Sea holly 'Big Blue' Eryngium x zabelii 'Big Blue'
- Sea holly 'Blue Hobbit' Eryngium planum 'Blue Hobbit'
In these guides
- Plants for wet soil and rain gardens
- Deer-resistant perennials for full sun
- Rabbit-resistant plants
- Drought-tolerant perennials for full sun
- Pet-safe plants for a sunny border
- Native perennials for pollinators
- Plants for butterflies
- Plants for bees
- Tall perennials and grasses for the back of a border
- Plants for a white garden
Zone guides: Zone 3 · Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8
Every fact on record
- Type
- Perennial
- Size
- 4 ft (120 cm) tall, 24 in (60 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back, or further forward: it is airy enough to see through
- Flowers
- Mid July to late August; globes; white
- Leaves
- Bold texture, herbaceous; blue-green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 3 to 8
- Light
- Full sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Apiaceae
- Comes from
- U. S. native
- Attracts
- Pollinators, bees, butterflies, moths
- Host plant for
- Rattlesnake-master borer
- Stands up to
- Deer, rabbits, drought, wet soil
Checked against NC State Extension. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.