My Everchanging Garden

Gardening That Grows With Me

Growing Cosmos – Still Finding My Favourite

I love the delicate blooms of cosmos, but honestly, there are too many to choose from! I grow cosmos mostly in the Circle Garden, with a few more near the vegetable gardens for the pollinators.

This is my personal garden growing guide. I use it to track seed sources, when to start seeds and if I should adjust growing conditions in my own greenhouse and garden. Please don’t consider this professional grower’s advice.


I’m still playing with a combination of cosmos, zinnias and gomphrena in the Circle Garden.  I didn’t like Versailles Red blooming at the same time as the purple clematis (The President) and drumstick allium. I did like the pink and purple-fuchsia combination of the gomphrena I tried in 2023 with Capriola cosmos.

So for 2024, I’m gravitating more toward pink cosmos mid-border and will add a deeper pink zinnia towards the centre. Eventually, I might find my favourite colour combo!

Swallowtail Garden Seeds

  • Versailles Red (Cosmos bipinnatus) – early blooming, vigorous, stronger stems
  • Capriola (Cosmos bipinnatus) – heavy flowering, dwarf (24-30 inches)
  • Apollo Pink (Cosmos bipinnatus, hybrid) – new trial 2024, dwarf habit, 4-inch flowers
  • Apollo Carmine (Cosmos bipinnatus, hybrid) – new trial 2024, dwarf habit, 4-inch flowers

William Dam Seeds

  • Cranberries (Cosmos bipinnatus, Double Click Series) – 31-40 inches

Hawthorn Farm Organic Seeds

  • Blush Cupcake – new trial 2024. Fused petals produce a cup-like flower. Tall – 36-48 inches.
Hardiness blooms till frost
Exposure full sun to part shade
Deer resistant yes
Bloom time & length Summer to fall, flower in 10-12 weeks, so late start
Deadheading, care cut off spent blooms
Water & soil conditions dry to medium, drought-tolerant
Spacing 12-15 inches

My own notes:

I’ve grown cosmos in the Triangle Garden in the past (Sensation Mix) and now mostly in the Circle Garden.

annuals and clematis in bloom in my circle garden

Annuals including cosmos and gomphrena in the Circle Garden in early July 2023

For 2024:

  • trying shorter varieties
  • start later and prune centres while in pots (this will delay flowers)


  • 6 weeks before frost is around April 8
  • Sow 1/4 inch deep, cover lightly
  • Use tempered water to maintain temperature
  • Germinates 7 to 21 days at 70-80°F / 21-27°C


  • grow cooler 64-68°F / 18-20°C day, couple degrees cooler at night
  • pinch out the growing tip when there are three pairs of true leaves
  • to force flowers, use artificial light. Eleven hours per day once seedlings have emerged. After 2 weeks, keep lights on for 14 hours or more per day.


  • pinch plant tips again when plants are 18 inches high
  • plants may bloom better in poor soil
  • very drought-tolerant

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