Crazy about Cosmos

By Glennis Byron
August 25, 2023
Filed in Flowers
4 minutes

I never realised until this year that some species of bees sleep in flowers. Apparently they are always male: the sensible females retreat to an underground nest when they want a snooze. In my garden, by far the most popular flowers for either a quick nap or an overnighter seem to be zinnias and cosmos, and since the flower beds from which I cut most frequently are late to receive the first rays of sunshine, I have to be very careful when cutting in the early morning. This little fellow in the red zinnia below was well tucked away, and it was only when I grabbed the stem and the flower shook that the little bee bum emerged from under the petals and started to quiver. I’m not the biggest fan of zinnias myself, but I share with the snoozing bees a great love for Cosmos bipinnatus.

I remember back when the only cosmos seeds I could find were ‘Sensation’ or ‘Sonata’ mix. They are still available (now known as ‘heirloom’ cosmos and doesn’t that make me feel ancient) but there are far more beautiful varieties to grow now and I find them an essential both in the garden and in summer bouquets. They seem able to grow anywhere: I’ve grown them in wet and windy central Scotland and in my hot and dry Spanish garden (the goldfinches used to gorge on the seeds) and my father grew them in the middle of the Canadian Rockies (after the last frost of course). I’m always surprised just how long they last in the vase, particularly if you include a few buds ready to burst.

These are some of my favourite this year:


I think ‘Rubenza’ is quite an old variety, but this was my first time growing it and I love the way the flowers start as a gorgeous deep cranberry and gradually fade to a soft antique rose; they also have a rather distinctive pleated effect and last exceptionally well both on the plant and in the vase. Pure happenstance, but I planted them next to my two new ‘Distant Drums’ roses, and they work so well together, with the cosmos picking up shades from both the leaves and the flowers of the rose. Put them with some annual Phlox ‘Cherry Caramel’ and you have a really smashing combination.

‘Fizzy Rose Picotee’

My absolute favourite of all the cosmos I grew this year, ‘Fizzy Rose Picotee’ has a variable base, pale pink to white to mauve, and a magenta picotee. All the ‘Fizzy’ series are pretty – they have a smaller row of little petals that makes them a semi-double – but this is the prettiest and looks particularly good raised a little in the bouquet.

Even the ordinary Cosmos ‘Picotee’ is well worth growing and also makes a lovely addition to bouquets.

‘Double Click’ series

This is a pretty and relatively new series, all with double and semi-double blooms, the former being very frilly knickers and the latter looking a little more like the Seashells series. ‘Double Click Cranberry’ is good, a delicious deep cranberry colour, rich and showy. I found the pure white form disappointing as the flowers were small and scrappy, and my neighbour found the same. Another thing to note with the ‘Double Click’ series is that the flowers have such heavy heads that they sometimes begin to droop quickly. I don’t mean wilt, because they have quite a long vase life, but the heaviness of the heads makes them droop over. But how could you complain about the absolutely gorgeous ‘Rose Bicolour’? It’s the very best in this series, beautifully ruffled in shades of white and rose pink and surely the ultimate romantic flower.


‘Xanthos’ just makes the cut here, because it is a truly beautiful flower, a soft lemony yellow, and a great garden plant, more compact than most cosmos. But I’m wavering, because it’s not as floriferous as others, and it isn’t so easy to get a good long stem.

Sowing and growing: Cosmos should be started inside 5-7 weeks before the last frost, and cover only lightly as light helps germination. You can also direct sow after the last frost. Most cosmos can grow quite large and tall: plant in groups and you’ll find they support each other and won’t topple over. Be ruthless about pinching them when small and cut deep, don’t just deadhead, once they are flowering. If you don’t do these two things, you’ll end up with cosmos trees that give lots of lovely ferny foliage but very few flowers. You can let them self seed each year, but eventually they will revert and you’ll lose the original colours you first sowed.

Harvesting: pick lots, and cut deep into the plant when you harvest, and they’ll respond with a constant production of flowers. Try to get some flowers when they are just opening up.

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1 comment

  • Elizabeth Fraser Jackson

    Always pleased to see your work. 💕💕💕

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