Chocolate cosmos Cosmos atrosanguineus
Chocolate cosmos (Cosmos atrosanguineus) is a deciduous perennial flowering plant in the Asteraceae family, native to Mexico (extinct in the wild). It grows 40–75 cm (16–30 in) tall and 30–45 cm (12–18 in) wide, wants full sun and moderate water, and is hardy to about -5 °C (23 °F). Space plants about 35 cm (14 in) apart.
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Chocolate cosmos at a glance
| Type | Perennial flowering plant, deciduous |
|---|---|
| Family | Asteraceae |
| Mature height | 40–75 cm (16–30 in) |
| Mature spread | 30–45 cm (12–18 in) |
| Spacing | 35 cm (14 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance none |
| Soil pH | 6–7.5 |
| Cold hardiness | About -5 °C (23 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 32 °C (90 °F) |
| Flowering | from about July for 10–17 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Mexico (extinct in the wild) |
| Common in gardens of | 🇲🇽 Mexico, 🇬🇧 United Kingdom, 🇺🇸 United States, 🇳🇿 New Zealand, 🇯🇵 Japan |
Is Chocolate cosmos toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
No toxicity reported in standard poison references.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Chocolate cosmos
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Questions about Chocolate cosmos
- How far apart should I plant Chocolate cosmos?
- About 35 cm (14 in) apart, centre to centre. A mature plant spreads 30–45 cm (12–18 in).
- Does Chocolate cosmos need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Chocolate cosmos need?
- Moderate water. Drought tolerance is low and waterlogging tolerance none.
- How cold-hardy is Chocolate cosmos?
- It tolerates about -5 °C (23 °F) once established, roughly USDA zone 9.
- When does Chocolate cosmos flower?
- From about July for 10–17 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Chocolate cosmos poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. No toxicity reported in standard poison references.
- What grows well with Chocolate cosmos?
- There is no well-documented companion pairing for Chocolate cosmos. Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- RHS Plant Finder, Royal Horticultural Society
- Plants of the World Online (taxonomy, native range), Royal Botanic Gardens, Kew
Notes and assumptions
- Velvety maroon flowers smell of chocolate and vanilla on warm days. Grown from a single sterile clone; lift the tubers like dahlias where winters are cold.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Lettuce Lactuca sativa
- Sunflower Helianthus annuus
- French marigold Tagetes patula
- Zinnia Zinnia elegans
- Cosmos Cosmos bipinnatus
- Purple coneflower Echinacea purpurea
- Black-eyed Susan Rudbeckia hirta
- French tarragon Artemisia dracunculus