Cosmos sulphureus Klondike Mixed

RHS Plant Profile
cosmos [Klondike Mixed]

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cosmos [Klondike Mixed] RHS / Joanna Kossak
cosmos [Klondike Mixed] RHS / Joanna Kossak
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Annual Biennial

A half-hardy annual, to around 90cm tall, with finely-divided foliage and semi-double flowers in shades of yellow and orange produced from summer into autumn

Position

Full sun

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
1 year
Max Spread
0.1-0.5 metres
Max Height
0.5-1 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun
Aspect
South–facing or East–facing or West–facing
Exposure
Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

  • H1A: under glass all year (>15C)
  • H1B: can be grown outside in the summer (10 - 15)
  • H1C: can be grown outside in the summer (5 - 10)
  • H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
  • H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
  • H4: hardy through most of the UK (-10 to -5)
  • H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
  • H6: hardy in all of UK and northern Europe (-20 to -15)
  • H7: hardy in the severest European continental climates (< -20)
H3

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Asteraceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Columnar upright
Genus
Cosmos can be annuals or perennials with simple or pinnately divided leaves and large, long-stalked daisy-like flowers in summer
Name Status
Trade

How to Grow

Cultivation

Grow in moderately fertile, moist but well-drained soil in full sun

Propagation

See sowing seeds indoors

Suggested planting locations and garden types

  • Cottage and informal garden
  • Patio and container plants
  • Wildlife gardens
  • City and courtyard gardens
  • Coastal
  • Flower borders and beds
  • Cut flowers

Pruning

Deadheading should be carried out regularly to prolong flowering

Pests

Aphids and slugs may be a nuisance

Diseases

May be susceptible to grey moulds