Cosmos

Photographs by Sabina Rüber

'Fizzy Pink'
'Fizzy Rose Picotee'
Cosmos Purity
'Purity'

Cosmos is my favourite summer annual. It’s so satisfying to grow, with fresh-green ferny seedlings that develop over a matter of weeks into substantial plants, some of which reach 4-5ft tall. Originating in Mexico and South America, cosmos is a tender plant that baulks at the slightest frost – but by the time the first frosts come it will have more than earned its keep, flowering continually if you keep cutting. Cosmos can of course be found as plants in the garden centre – but you’ll soon discover that the range of colours and varieties is much wider when grown from seed, from deep ruby-crimson to eggshell white, with picoteed, quilled and ruffled flowers also thrown in to the mix. 

The easiest and most elegant cosmos to slot into a border is C. bipinnatus ‘Purity’, which has snow-white flowers on tall willowy stems. It looks particularly good with Ammi, Nicotiana ‘Lime Green’, and other green-flowered stalwarts like alchemilla or bupleurum. Of the darker varieties, ‘Rubenza’ has the most striking flowers the colour of red wine in the centre, lightening to carmine-pink on the petal-edges, and contrasting with a gold boss in the centre. ‘Versailles Tetra’ is a lighter pink, but with an even more pronounced dark ring around the central eye. The semi-double 'Fizzy Series' come in pink and white, while the gorgeous 'Fizzy Rose Picotee' has palest pink blooms with picotee edges and a delicate frill in the centre. 

I would grow all of them – seriously – as they are so gloriously easy to raise from seed. They can be sown direct in late spring, but I prefer to sow them in small 7cm pots or modules in March or April. Sow two seeds to a pot and remove the weaker seedling as they emerge. As the seedlings grow to about 5cm, you can pinch out the tips to produce bushier, sturdier plants. Then either pot them on or plant them out in May in a sunny, well-drained spot, and they will show you how grateful they are. 

Back to The Flower Garden main page.