Mountain bluet 'Amethyst in Snow'
Centaurea montana 'Amethyst in Snow' · Asteraceae
Spidery white cornflowers, each with a centre of deep amethyst purple, over silvery leaves in late spring.
- Size
- 18 in tall, 24 in wide
- Zones
- 3 to 8
- Light
- Full sun to part sun
- Flowers
- Late May to late June
- Pets
- No toxicity recorded
- Job in a bed
- Drift
A bed built around mountain bluet 'Amethyst in Snow'
The planner designed this bed around mountain bluet 'Amethyst in Snow' when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why mountain bluet 'Amethyst in Snow' stands where it does.
The plants
- 1 Mountain bluet 'Amethyst in Snow' × 3, white
- 2 Winter heath × 7, pink
- 3 Leadwort × 8, blue
- 4 False sunflower 'Summer Nights' × 3, yellow
- 5 Little bluestem 'The Blues' × 8, tan
- 6 Silver sage × 1, silver leaves
- 7 Star of Persia × 3, purple
Why this plant
- The only white. White sits between stronger colours and calms them.
Why here
- In the middle. At 18 in it is the step between leadwort (10 in) in front and little bluestem 'The Blues' (3 ft) behind: each is seen over the one before.
- 3 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for six weeks. From late May to late June.
- Fills a gap. For one of those weeks nothing else on the plan is in flower.
Planned as an English border: 5 of the 7 groups (71%) are drifts, longer along the bed than they are deep. Low plants run along 95% of the front edge: silver sage, winter heath and leadwort. The most in flower at one time is 3 kinds, from early August.
The planner's own design check: 11 Excellent, 5 Good, 1 Satisfactory. 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 mountain bluet 'Amethyst in Snow' goes in a border
At 18 in it belongs at the front of a bed. In the planner's ten height classes it is short (12 to 18 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
The two-tone flower is striking at close range, so plant it near a path. It spreads less than the blue species, and flowers again if cut back hard in June.
- Late-spring flowers beside a path
- Cottage gardens
- Cutting
What to plant with mountain bluet 'Amethyst in Snow'
Plants recorded as good partners for it, and what each pairing does:
- Lady's mantle: in flower together for five weeks, from late May.
- Bearded iris: purple against yellow, opposite each other on the colour wheel, if you choose those colours, in flower together for four weeks; tall enough (2½ ft) to stand behind it.
- Peony: in flower together for four weeks, from late May; tall enough (3 ft) to stand behind it.
Questions about mountain bluet 'Amethyst in Snow'
Does mountain bluet 'Amethyst in Snow' need sun or shade?
Mountain bluet 'Amethyst in Snow' grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).
It wants ordinary well-drained soil, of average fertility, and little watering once settled. It copes with soil that stays wet.
What zones does mountain bluet 'Amethyst in Snow' 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 mountain bluet 'Amethyst in Snow' flower in my zone?
In zone 5 it flowers late May to late June. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.
| Zone 3 | Early June to early July |
|---|---|
| Zone 4 | Late May to early July |
| Zone 5 | Late May to late June |
| Zone 6 | Mid May to late June |
| Zone 7 | Early May to late June |
| Zone 8 | Early May to late June |
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 mountain bluet 'Amethyst in Snow' 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 18 in (45 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many mountain bluet 'Amethyst in Snow' 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 a group of three or five, with a second group further along in the other number.
In the bed above, the planner used three in one group.
Is mountain bluet 'Amethyst in Snow' 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 mountain bluet 'Amethyst in Snow'?
They may. NC State does not list it as resistant to deer or rabbits. Where they visit, protect it, or plant it among ones they avoid.
Will mountain bluet 'Amethyst in Snow' spread?
It spreads sideways, by runners or roots; the risk of it taking over is moderate. Spreads by creeping roots and by seed, though less than the species. Cut it back after flowering.
What flowers after mountain bluet 'Amethyst in Snow'?
Mountain bluet 'Amethyst in Snow' is over by late June. These start as it finishes and carry the same spot on, so it never goes flat:
- Black-eyed Susan: from mid July to mid September, 24 in tall.
- Butterfly weed: from late June to early August, 24 in tall.
- Daylily: from late June to early August, 2½ ft tall.
What does mountain bluet 'Amethyst in Snow' look like in winter?
Mountain bluet 'Amethyst in Snow' dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
Is mountain bluet 'Amethyst in Snow' good for bees and butterflies?
Mountain bluet 'Amethyst in Snow' is visited by bees and butterflies.
More Centaurea
- Mountain bluet Centaurea montana
- Persian cornflower Centaurea dealbata
In these guides
- Plants for wet soil and rain gardens
- Pet-safe plants for a sunny border
- Plants for butterflies
- Plants for bees
- Silver and grey-leaved plants
Zone guides: Zone 3 · Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8
Every fact on record
- Type
- Perennial
- Size
- 18 in (45 cm) tall, 24 in (60 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Short (12 to 18 in)
- Place in the bed
- Front
- Flowers
- Late May to late June; globes; white, purple
- Leaves
- Medium texture, herbaceous; grey-green
- Shape
- Mounding, spreading
- Hardy in
- USDA zones 3 to 8
- Light
- Full sun, part sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Asteraceae
- Comes from
- Europe
- Attracts
- Bees, butterflies
- Stands up to
- Wet soil
Checked against NC State Extension and VASCAN (plants of Canada). 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.