Cosmos Species, Black Cosmos, Chocolate Cosmos

Cosmosatrosanguineus

Family
Asteraceae (ass-ter-AY-see-ee)
Genus
Cosmos (KOS-mus)
Species
atrosanguineus (at-ro-san-GWIN-ee-us)
Synonym
Bidens atrosanguinea
Cosmos diversifolius var. atrosanguineus
Sun Exposure
Full Sun
Foliage
Evergreen
Height
18-24 in. (45-60 cm)
Spacing
24-36 in. (60-90 cm)
Hardiness
USDA Zone 8a: to -12.2 °C (10 °F)
USDA Zone 8b: to -9.4 °C (15 °F)
USDA Zone 9a: to -6.6 °C (20 °F)
USDA Zone 9b: to -3.8 °C (25 °F)
USDA Zone 10a: to -1.1 °C (30 °F)
USDA Zone 10b: to 1.7 °C (35 °F)
Danger
N/A
Bloom Color
Maroon/Burgundy
Bloom Time
Late Spring/Early Summer
Mid Summer
Late Summer/Early Fall
Mid Fall
Late Fall/Early Winter
Other Details
Category
Perennials
Tropicals and Tender Perennials
Water Requirements
Average Water Needs; Water regularly; do not overwater
Requires consistently moist soil; do not let dry out between waterings
Foliage Color
Where to Grow
Bloom Characteristics
Flowers are fragrant
Bloom Size
Other details
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
Non-patented
Propagation Methods
By dividing the rootball
Seed Collecting
N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed
Regional

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

Albany, California

Arroyo Grande, California

Hydesville, California

Madera, California

Napa, California

Salinas, California

San Francisco, California

San Jose, California

Naugatuck, Connecticut

Wilton, Connecticut

Washington, District of Columbia

Carrollton, Georgia

Valdosta, Georgia

Divernon, Illinois

Cambridge, Massachusetts

Manchester, New Hampshire

Mount Laurel, New Jersey

Corvallis, Oregon(2 reports)

Hillsboro, Oregon

Portland, Oregon

WALTERVILLE, Oregon

Conway, South Carolina

Collierville, Tennessee

Austin, Texas

Lubbock, Texas

Sugar Land, Texas

Tyler, Texas

Vernal, Utah

CHIMACUM, Washington

Kalama, Washington

Langley, Washington

Seattle, Washington(2 reports)

Spokane, Washington

Tacoma, Washington

show all

Featured Videos

Gardener's Notes:

15
positives
6
neutrals
1
negative
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O
Hillsboro, OR | September 2023 | neutral

I planted this plant in full sun near Portland, OR. We are about 1300 feet elevation and usually 7-10 degrees cooler and warmer than Port...Read More

J
Collierville, TN | July 2020 | positive

My Chocolate Cosmos is putting out its first bloom today. Last winter I covered the plant with frost blanket and im so happy to see tha...Read More

H
| August 2015 | positive

This is the 2nd year's bloom of my Chocolate Cosmo.
I grow it in a container on my deck, it wintered very well, being cut back, ...Read More

C
ROSLINDALE, MA | January 2015 | negative

I've seen this species in many plantings around Boston, MA z6a (generally in planters rather than in the ground), and I've never seen a l...Read More

B
(Zone 7a) | January 2015 | positive

This plant has produced seeds, and seeds are sometimes for sale by JonnaSudenius. Her website is on her DG member page.

G
Sugar Land, TX | June 2010 | positive

I planted a chocolate cosmos in my garden this spring. It grew about a 18" tall, with tiny, 1 inch deep maroon-to-brown blooms atop lon...Read More

C
C
Missoula, MT (Zone 5a) | September 2008 | positive

The color of these flowers is more chocolaty than their fragrance. For a real treat, I'd like to combine this plant with Berlandiera - w...Read More

F
Huron, SD | January 2008 | neutral

Contrary to what someone else said here, this clone is NOT of European origin. This self-sterile species is EXTINCT in the wild [Mexico] ...Read More

L
Seattle, WA | April 2006 | positive

My Chocolate Cosmos thrive in full sun.

They have an aroma like that of a cup of hot cocoa. They also have a deep red c...Read More

R
Albany, CA (Zone 10a) | October 2005 | positive

I've had a lot of trouble with mildew as well; I usually end up having to cut it way back and let it start over. My climate doesn't requ...Read More

S
| August 2005 | positive

Zone 5, Owen Sound, Ontario. Canada. My second year with chocolate cosmos.
I started last year with 10 of them, and I am down to ...Read More

C
Arroyo Grande, CA | July 2005 | positive

Good plant, blooms a long time. Dies back in the winter and returns in the summer. Subject to some mildew. Deadheading improves the du...Read More

F
(Zone 8a) | July 2005 | positive

I love this plant! It overwintered fine here in Northern UK in poor, well-drained soil, but struggled to regrow as slugs kept nibbling th...Read More

K
K
(Zone 7a) | September 2004 | neutral

I really like the smell of the flowers because they smell like Hersheys chocolate. I have found they are very easy to root. I have accide...Read More

S
Colorado Springs, CO | September 2004 | positive

I was living in Tacoma, Wa. where the pant grew wonderfully. I found it at a local nursery. It did need to be covered with hay in winter...Read More

S
S
(Zone 8b) | August 2004 | positive

I'm very fond of this plant. Well...the scent is a bitter chocolate one and of course its colour..a maroon/reddish brown gives you that e...Read More

G
Portland, OR | April 2004 | positive

I set this plant out in the early summer and had a great show of blooms through out the season and into early fall. Our area gets very w...Read More

Z
Z
| March 2003 | neutral

Hi everyone: )

I'm in zone 9 and thinking of using Chocolate Cosmos in a large rock garden between the rocks. Does anyone...Read More

F
F
| May 2002 | positive

Cosmos will flourish in regular, well drained, moist garden soil in a position that is well sheltered from strong winds. they love the s...Read More

G
G
Hampton, VA | March 2002 | neutral

The clone of this Cosmos, that is of European origin & widely available, is apparently sterile.
I have grown this from seed, found...Read More

E
E
(Zone 4b) | September 2001 | positive

Very lovely plant, loved the scent. The roots didn't overwinter for some reason, I moved them inside before the frost came.

J
J
MD &, VA (Zone 7b) | November 2000 | neutral

This species of perennial cosmos is clump forming, grows to about 2' high. Flowers smell like chocolate and are usually dark maroon/red i...Read More

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