Persian cornflower
Centaurea dealbata · Asteraceae
Fringed, rosy-purple cornflowers with pale centres stand on stiff stems above deeply cut leaves that are green above and white beneath.
- Size
- 2½ ft tall, 24 in wide
- Zones
- 3 to 8
- Light
- Full sun
- Flowers
- Early June to mid July
- Pets
- Not checked
- Job in a bed
- Drift
A bed built around persian cornflower
The planner designed this bed around persian cornflower 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 persian cornflower stands where it does.
The plants
- 1 Persian cornflower × 3, pink
- 2 Winter heath × 8, white
- 3 Sea thrift × 9, pink
- 4 Brown-eyed Susan × 3, yellow
- 5 Silver sage × 1, silver leaves
- 6 Goldenrod 'Golden Fleece' × 3, yellow
- 7 Sicilian honey garlic × 4, cream
- 8 Tulip 'Apeldoorn' × 8, red
Why this plant
- Nothing here is unique to it. Its leaf, flower shape and colour are all on the plan already. Its case rests on where it stands and when it performs.
Why here
- At the back. At 2½ ft it is seen over winter heath (10 in) in front of it, and has nothing behind it to hide.
- A step in the back row. Next to Sicilian honey garlic (3½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 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 early June to mid July.
- Fills a gap. For four of those weeks nothing else on the plan is in flower.
Planned as an English border: 6 of the 6 groups (100%) are drifts, longer along the bed than they are deep. The back corners are held by brown-eyed Susan and Sicilian honey garlic, the tallest plants on the plan. Sea thrift is planted in three places along the bed, which gives it rhythm.
The planner's own design check: 12 Excellent, 5 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 persian cornflower goes in a border
At 2½ ft it belongs in the middle of a bed. In the planner's ten height classes it is medium (24 in to 2½ ft).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
A tough, old-fashioned plant that asks for nothing. It flops in rich soil and spreads slowly at the root. Cut it to the ground after flowering for fresh leaves and a few more flowers.
- Cottage borders
- Poor, dry soil
- Cutting
What to plant with persian cornflower
Plants recorded as good partners for it, and what each pairing does:
- Catmint 'Six Hills Giant': in flower together for six weeks, from early June; spires rising out of its mound.
- Shasta daisy 'Becky': in flower together for two weeks, from early July.
- Blue oat grass: in flower together for five weeks, from early June.
Questions about persian cornflower
Does persian cornflower need sun or shade?
Persian cornflower 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.
What zones does persian cornflower 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 persian cornflower flower in my zone?
In zone 5 it flowers early June to mid July. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 3 | Mid June to mid July |
|---|---|
| Zone 4 | Mid June to mid July |
| Zone 5 | Early June to mid July |
| Zone 6 | Early June to mid July |
| Zone 7 | Late May to early July |
| Zone 8 | Late May to early July |
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 persian cornflower be planted?
20 in (50 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 2½ ft (75 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many persian cornflower plants do I need?
At 20 in apart, set out in staggered rows:
- 4 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 14 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.
Will persian cornflower spread?
It spreads sideways, by runners or roots; the risk of it taking over is moderate. Spreads slowly by creeping roots and can flop over neighbours. Divide it every three years.
What flowers after persian cornflower?
Persian cornflower is over by mid July. These start as it finishes and carry the same spot on, so it never goes flat:
- Shasta daisy 'Becky': from early July to early September, 3½ ft tall (a recorded partner).
- Black-eyed Susan: from mid July to mid September, 24 in tall.
- Lilyturf: from early August to mid September, 16 in tall, to stand in front of it and cover its fading stems.
What does persian cornflower look like in winter?
Persian cornflower 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.
More Centaurea
- Mountain bluet Centaurea montana
- Mountain bluet 'Amethyst in Snow' Centaurea montana 'Amethyst in Snow'
In these guides
Zone guides: Zone 3 · Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8
Every fact on record
- Type
- Perennial
- Size
- 2½ ft (75 cm) tall, 24 in (60 cm) wide
- Plant
- 20 in (50 cm) apart
- Height class
- Medium (24 in to 2½ ft)
- Place in the bed
- Middle
- Flowers
- Early June to mid July; globes; pink, purple
- Leaves
- Medium texture, herbaceous; green, grey-green
- Shape
- Mounding, spreading
- Hardy in
- USDA zones 3 to 8
- Light
- Full sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Asteraceae
Checked against 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.