PlantFiles: Common Cosmos, Mexican Aster
Cosmos bipinnatus

I have grown cosmos for years....the flower is my husband's and son's birthday month flower. I also notice them all over my little town in the Ojai Valley. For some reason, they are blooming earlier this year. Generally they bloom in October (when they are supposed to, because they are the flower for the month of October!). Easy to grow, I even have some popping up from seed in my cactus pots. Seems like the purple variety is the most durable and prolific. Like the foliage as well...feathery. Easy to grow, friendly to have around....not demanding in any way.

This plant is unlike anything I have ever come across.It was giving to me by a neighbor in a seed pack (with other seeds).It first came up it was 2 ft tall but no flowers.I transplanted it twice and now it sets alone in a 5 gal. bucket with awsome pink flowers.I'm 6ft tall and it is a bit taller than me.I have ended up tieing it up to keep it from falling over.This is one plant that I will plant next year and give some seeds away.

They are very pretty flowers, but need pinching back or staking early on to prevent flopping.

What can I say, but that I just love cosmos. C. bip regularly gets to 4-6 ft or more in my garden, though.

Cosmos are very easy to grow. I sow along the fenceline each spring. In 2004, they grew very tall (most measured at 9 feet high), mostly due to a combination of steer manure in the garden and the neighbor's active sprinklers sharing water along the fenceline. It was literally a jungle of cosmos. I kept dead-heading them, and they bloomed pretty much from July into October.

I especially love the star-shape pistil/stamen area as the pollen is released...very pretty. The dragonflies also appear to be attracted to the color...?

(Western Washington State)

I believe cosmos to be a "must have" for every garden. They are a beautiful flower.... now with so many fun varieties .... and so easy to grow! Simply scatter seeds in the garden and they will grow like mad! That being said they are also not harmfully invasive. Birds also love the seeds. Many of its colors blend nicely with other colors in the garden. Attractive divided foliage. A winner all around. Try it you will not be dissapointed! :)

Such great performance makes it a favorite in my SW garden.

Cosmos are easy to grow from seed sown directly in the garden in mid to late spring. They also self-sow vigorously, and they attract beneficial insects.

Best grown in poor soil; rich feeding leads to very big branches with poor flowering which tend to be floppy. Deadheading prolongs flowering.

Grows in Heat Zones 12-1.

This species of cosmos is an annual, grows 5' to 6' high. Flowers in summer and autumn in various colors of pink, red, white and purple. May need staking. Best cultivated in sun, with average soil. Not very frost hardy.