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A picture of a Cosmos

Cosmos

Cosmos bipinnatus

Also known as

Mexican Aster, Kosmos (Afr.)

Cosmos bipinnatus pink 02 by Kor!An (Корзун Андрей) (CC BY-SA 4.0)

Full Sun
Easy care
Moderate watering
Half-hardy

10a

USDA zone

-1°C

Minimum temperature

Expected size

Height
Spread

1.5m

Max

45cm

50cm

Min

20cm

6 months to reach maturity

Flowering

  • spring
  • summer
  • autumn
  • winter

This plant has no fragrance

More images of Cosmos

A close up of a pink flower of a Cosmos bipinnatus plant.
A close up of a pink flower of a Cosmos bipinnatus plant.
A close up of a pink flower of a Cosmos bipinnatus plant.

Cosmos Overview

Cosmos is a genus of about 25 species of erect to spreading, freely branched annuals and perennials found in scrub and meadows. The annual species C. bipinnatus is commonly grown in gardens on mass for the showy flowers. Cosmos was introduced to South Africa via contaminated horse-feed imported from Argentina during the Anglo-Boer War. It is now widespread over the high eastern plains of South Africa and invasive in certain areas.

Common problems with Cosmos

How to harvest Cosmos

Flowers can be harvested, pick the stems when buds are coloured but not open yet; this will keep insects from pollinating them and stretch the vase life by a few days. Collect seeds from ripened capsules and store them in a dry, cool dark location for use the following year. Alternatively, allow the seed to self-sow, transplanting seedlings in the spring to more desired locations.

How to propagate Cosmos

Seed

Sow between March and May into trays of per-watered seed compost and cover with 3mm sieved compost. Keep between 15-25C until they have germinated. Once the seedlings are large enough to handle (produced 2 leaves) transplant into 7cm (3") pots and move to a cooler location to continue growing. Plant out once the threat of frosts have passed and space each plant 45cm (18") apart.

Special features of Cosmos

Attracts useful insects

Attracts bees.

Autumn colour

Beautiful flowering beds in autumn if they are sown in well prepared beds.

Attractive flowers

Cultivars may range in colour from white, pink, orange, yellow and scarlet.

Other uses of Cosmos

These stunning flowers make lovely additions to mixed flower borders or grown in containers in almost all garden styles. Suitable for use in coastal locations.

Cut flower

The large flower on a long slender stem makes a pretty effect if displayed in bunches or mixed into other floral bouquets.

Garden Annuals

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