Cosmos

Photographs by Sabina Rüber

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 half hardy 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 think this one is also sometimes called ‘Sweet Sixteen’. I have just sown ‘Daydream’ for the first time this year which has palest pink petals with a darker centre. Buy seeds from Chiltern Seeds.

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, April and May. They need warmth to germinate, so bring them inside and put them on a warm windowsill at a temperature of about 18-22C. 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 after any danger of frost has passed, giving them a sunny, well-drained spot. I use them every year both in containers and to plug gaps in the border, and sow them successionally throughout spring so I always have cosmos flowers right the way into autumn - usually until the first frosts. Click here for a short video showing how to sow them.

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