Cosmos atrosanguineus (Chocolate cosmos)

Other names: Black cosmos, Black dahlia, Chocolate plant

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Species

C. atrosanguineus is a spreading perennial, with divided leaves and chocolate-scented, dark maroon flowers.

Season of interest

Flower
	Spring	Summer	Autumn	Winter
Flower
Foliage
	Spring	Summer	Autumn	Winter
Foliage

Height and spread

Metric |
Imperial

Height and spread Metric \| Imperial
Size	Max height	Max spread	To maturity
1 m	0.5 m	2-5 years
3 ft	1 ft	2-5 years

Height and spread

Metric |
Imperial

Size

Max height

Max spread

To maturity

1 m

0.5 m

2-5 years

3 ft

1 ft

2-5 years

Where to grow

Soil

Soil type

Chalky
Loamy
Sandy

Soil drainage

Moist but well-drained
Well-drained

Soil pH

Acid
Alkaline
Neutral

Conditions

Sunlight

Full Sun

Aspect

West
South

Exposure

Exposed
Sheltered

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Additional plant details

Cultivation

Grow in moderately fertile, moist, but well-drained soil in sun. Mulch in autumn. In very cold areas, lift tubers before first frost and store in moist peat until spring.

Suggested uses

Flower Arranging, Beds and borders, Cottage/Informal, City

UK hardiness

USDA zones

Zone 7, Zone 8, Zone 9, Zone 10

Sunset zone

4, 5, 6, 7, 8, 9, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

WUCOLS

North-Central Coastal = Moderate/Medium
Central Valley = Moderate/Medium
South Coastal = Moderate/Medium
South Inland = Moderate/Medium
High and Intermediate Desert = Unknown
Low Desert = Unknown

Foliage

Deciduous

Habit

Bushy, Clump-forming

Native to

Mexico

Drought tolerant

Flood tolerant

Fragrance

Chocolate scented

Toxicity

Not edible.

Plant care

Pruning

Deadhead regularly to encourage flowering.

Propagation methods

Seed

Pests

Diseases

Grey mould

Foot and root rot

Monthly care advice

Deadhead regularly (optional)

Plant container grown plants in a sunny sheltered spot

Protect in winter with dry mulch (in cold areas)

Lift and store Dahlia and Canna tubers in frost-free place (optional in cold areas)

Take basal cuttings

Plant in moist but well-drained soil (autumn or spring)

Other plants

Plants in this Genus (67)

Cosmos

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Cosmos bipinnatus 'Versailles Tetra' Cosmos 'Versailles Tetra'

Cosmos sulphureus Brightness Series Yellow cosmos Brightness Series

Cosmos bipinnatus 'Sonata Carmine' (Sonata Series) Cosmea 'Sonata Carmine'

Cosmos bipinnatus 'Sonata Pink' (Sonata Series) Cosmea 'Sonata Pink'

Cosmos bipinnatus 'Purity' Cosmea 'Purity'

Cosmos bipinnatus Sonata Series Cosmea Sonata Series

Cosmos atrosanguineus Chocolate cosmos

Cosmos sulphureus 'Ladybird' Cosmos 'Ladybird'

Cosmos bipinnatus 'Candy Stripe' Cosmos 'Candy Stripe'

Cosmos 'Chocamocha' Cosmos 'Chocamocha'

Cosmos sulphureus 'Cosmic' Cosmos 'Cosmic'

Cosmos bipinnatus 'Cosmonaut' Cosmos 'Cosmonaut'

Cosmos bipinnatus 'Double Click' Cosmos 'Double Click'

Cosmos bipinnatus 'Gazebo Mixed' Cosmos 'Gazebo Mixed'

Cosmos bipinnatus 'Sea Shells' Cosmea 'Sea Shells'

Cosmos bipinnatus 'Sensation Mixed' Cosmos 'Sensation Mixed'

Cosmos bipinnatus 'Sonata White' Cosmea 'Sonata White'

Cosmos bipinnatus 'Sensation Pinkie' Cosmea 'Sensation Pinkie'

Cosmos bipinnatus 'Dazzler' Cosmea 'Dazzler'

Cosmos bipinnatus 'Double Click Snow Puff' (Double Click Series) Cosmea 'Double Click Snow Puff'

Cosmos bipinnatus Dwarf Wonder Mix Cosmea Dwarf Wonder Mix

Cosmos bipinnatus 'Antiquity' Cosmea 'Antiquity'

Cosmos bipinnatus 'Daydream' Cosmea 'Daydream'

Cosmos bipinnatus 'Gloria' Cosmea 'Gloria'

Cosmos 'Yellow Garden' Cosmea 'Yellow Garden'

Related content

Re: Re: Chocolate Cosmos Mold Problem

Shoot User

2000 0

Thanks so much. I actually have all those ingredients in the house so I can make it immediately.

Posted: Friday 30th of September 2011 03:46 PM

Re: Chocolate Cosmos Mold Problem

Shoot User

2000 1

Clip off all the leaves affected by the mildew. Mildew likes a humid environment. I found this recipe on the web but have not used it personally or on a plant ;-) .As the chocolate Cosmos isn't hardy (Tender in frost (H3)) it might be worth lifting them now and putting in a greenhouse. Don't water the plants from overhead, this can spread spores.A mulch also can prevent the spores rising.You did the correct thing by increasing air fow to the plants.
Patricia

Ingredients:
•1 gallon of water
•1 tablespoon of baking soda
•1 tablespoon of vegetable oil
•1 tablespoon of dishwashing liquid
Mix the ingredients together and add them to a spray bottle. Spray your plants weekly, preferably on overcast days to prevent it from burning the foliage.

Posted: Monday 5th of September 2011 10:35 AM

Chocolate Cosmos Mold Problem

Shoot User

2000 1

I have 3 plants and all are suffering from a white mildew up the stems. The plants are well spaced out and in between them I have Euphorbia (Diamond Frost) but I've kept them all quite well spaced to allow for air. How can I treat this or do I need to destroy the plants. I had planned on taking cuttings but that looks unlikely now.

Images -
1. The white mildew on the stems.
2. This brown marking is on the back on some leaves.
3. From above to see the spacing.

I keep the ground clear of leaves and weeds.

Any help would be appricated.

Click to enlarge images

Posted: Sunday 4th of September 2011 05:20 PM Last reply: Monday 17th of March 2025 07:33 AM

Cosmos atrosanguineus

Shoot User

837 0

Cosmos is a tall tuberous plant, originally from North America. The hummingbird hawk-moth may be the most spectacular insect to be found on cosmos but it may also attract many other nectar feeding insects into a garden, including bees.

Posted: Wednesday 20th of May 2009 08:33 AM Last reply: Friday 28th of February 2025 12:24 PM