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Cosmos bipinnatus

Common Cosmos · Garden Cosmos · Mexican Aster

Family AsteraceaeGenus Cosmos

A single pink flower of eight broad notched petals around a bright yellow center
FlowerGeorge ChernilevskyCC BY 4.0

About the plant

What it is and where it grows — not part of any germination protocol.

The plant

Habit
AnnualExtension Gardener Plant Toolbox
Habit
annualPlants of the World Online
Height
2-4 ft0.6-1.2 mExtension Gardener Plant Toolbox
Spread
2-3 ft60-90 cmExtension Gardener Plant Toolbox
Flower
Gold/Yellow, Pink, Purple/Lavender, WhiteExtension Gardener Plant Toolbox
Blooms
Fall, Spring, SummerExtension Gardener Plant Toolbox
Native range
Mexico Central, Mexico Gulf, Mexico Northeast, Mexico Northwest, Mexico SouthwestGBIF Backbone Taxonomy
Hardiness zones
2-11Extension Gardener Plant Toolbox

Growing conditions

Sun
Full sun; Partial ShadeExtension Gardener Plant Toolbox
Soil
Clay, Loam (Silt), SandExtension Gardener Plant Toolbox
Soil pH
Alkaline (>8.0), Neutral (6.0-8.0)Extension Gardener Plant Toolbox
Moisture
Good Drainage, Occasionally DryExtension Gardener Plant Toolbox

Toxicity is noted only where a source states it. No note here is not a finding of safety.

Sources: Extension Gardener Plant Toolbox — NC State Extension; Plants of the World Online — Royal Botanic Gardens, Kew; GBIF Backbone Taxonomy — Global Biodiversity Information Facility.

Worth knowing

  • Flowering begins 60 to 90 days after germination. Grown as an ornamental in many countries and prone to naturalizing, it has become invasive in many parts of the world. Wikipedia: Cosmos bipinnatus

Protocol

DerivedN. C. Deno, 1998

Difficulty Moderate Rated by us, not by the source.

  1. Dry storage

    Duration: 365 daysTemperature: 70°F 21°C

  2. Sow and cover

    Temperature: 70°F 21°C Light: dark

about 12 months from start to sowing. Then 14 days to germinate.

50% germination in 14 days.

Seed Germination Theory and Practice, 2nd Supplement — N. C. Deno, 1998 · 2nd Supplement, Cosmos p. 26Public domain
Show the original text
Cosmos (Asteraceae). C. bipinnatus DS 1 y germ. 70D(50% in 2nd w). HC reported that germination was the same from 50-80 but dropped to about half at 85.
Seed Germination Theory and Practice, 2nd Supplement, 2nd Supplement, Cosmos p. 26. Quoted exactly. Every value on this card comes from this record, except the difficulty rating, which is ours; the step names come from a fixed list.

How each step is done, in Deno’s words, and what Verified and Derived mean.

Germination trials

Readers’ own records of sowing this species, published after review. Share your trial · All trials

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