Psephellus Species, Knapweed, Persian Cornflower

Psephellus dealbatus

Family: Asteraceae (ass-ter-AY-see-ee) (Info)
Genus: Psephellus
Species: dealbatus (day-al-BAH-tus) (Info)
Synonym:Centaurea dealbata



Water Requirements:

Drought-tolerant; suitable for xeriscaping

Average Water Needs; Water regularly; do not overwater

Sun Exposure:

Full Sun

Sun to Partial Shade

Light Shade




Foliage Color:



18-24 in. (45-60 cm)

24-36 in. (60-90 cm)


15-18 in. (38-45 cm)

18-24 in. (45-60 cm)


USDA Zone 3a: to -39.9 C (-40 F)

USDA Zone 3b: to -37.2 C (-35 F)

USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

Where to Grow:

Grow outdoors year-round in hardiness zone



Bloom Color:


Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Bloom Size:

Unknown - Tell us

Bloom Time:

Late Spring/Early Summer

Mid Summer

Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

By dividing the rootball

From seed; direct sow after last frost

Self-sows freely; deadhead if you do not want volunteer seedlings next season

Seed Collecting:

Allow seedheads to dry on plants; remove and collect seeds


This plant is said to grow outdoors in the following regions:

Booneville, Arkansas

Edwardsville, Illinois

Saint Charles, Illinois

Wauconda, Illinois

Foxboro, Massachusetts

Constantine, Michigan

Mason, Michigan

Pinconning, Michigan

Hopkins, Minnesota

Minneapolis, Minnesota(2 reports)

Rosemount, Minnesota

Saint Paul, Minnesota

Saint Joseph, Missouri

Manchester, New Hampshire

Buffalo, New York

Wallkill, New York

Richfield, Ohio

Bartlesville, Oklahoma

, Ontario

Knoxville, Tennessee

Austin, Texas

Weatherford, Texas

Salt Lake City, Utah

Leesburg, Virginia

Cathan, Washington

John Sam Lake, Washington

Kalama, Washington

Lynnwood, Washington

North Marysville, Washington

Poulsbo, Washington

Priest Point, Washington

Seattle, Washington

Shaker Church, Washington

Stimson Crossing, Washington

Weallup Lake, Washington

Eau Claire, Wisconsin

Menasha, Wisconsin

show all

Gardeners' Notes:


On May 8, 2016, coriaceous from ROSLINDALE, MA wrote:

According to the RHS, C. hypoleuca is a different species, not a synonym.


On Apr 4, 2008, Malus2006 from Coon Rapids, MN (Zone 4a) wrote:

Tough species - I have never seen them selfseed. Bloom a bit later than C. montana and have heavily lobed leaves that stays close to the ground. More uncommonly sold compare to C. montana. A common name is Tall Bachelor's Button.


On Jun 11, 2007, bakingbarb from Lynnwood, WA wrote:

Flowers are wonderful addition to the garden. The plant is spreading though so plant it where you have lots of space. Also it is easy to dig up the baby plants, just make sure to get some roots with it.


On Jul 4, 2006, bigcityal from Appleton, WI (Zone 5a) wrote:

Nice carefree flower. Finer cut foliage than regular cornflower. Gold finches eat all the seeds so I don't know if it self seeds.


On Aug 10, 2005, flowercrazy39 from Manchester, NH wrote:

Mine just flowered this summer for the first time and I love it! No mildew, no bugs eat it, just beautiful flowers, no fuss.


On Jul 23, 2004, peonylady from Anchorage, AK wrote:

Our USDA zone is usually 3, although we have had
several favorable winters lately. The Persian Cornflower
has performed very well, has not reseeded agressively here,
grows strongly, may need dividing every third year to keep it
in bounds, color and form is very attractive, and it is
especially nice to photograph.