Cosmos are not as simple as they were. When I started gardening, there was only ‘Sensation’ mixed, an early-flowering strain of C. bipinnatus. Then we got short ones, a wider range of colours, doubles and the strange ‘Cupcakes’ (which no one has yet explained to me – it seems structurally impossible to me). And more recently we have had pale yellows and now apricot.

For a while, the fabled rarity status of C. atrosanguineus, the chocolate cosmos, made it popular. Thought to be sterile, it remained rare and then plants were found in the wild and seeds were produced and now it is relatively common. The dark flowers are cute but despite the promise of chocolate scent, it is more dusty cocoa than Cadbury’s. This species is not an annual but a tuberous perennial confirming the close relationship with dahlias.

‘Flamingo’ is a perennial that is often named as C. peucedanifolius (parsnip-leaved) and there was a hint, some time ago, that it was a hybrid of C. atrosanguineus. I bought it believing the flowers were scented of chocolate. I can confirm that this is not the case. I can detect no scent. I also see that seeds of ‘Flamingo’ or at least Cosmos peucedanifolius are available. And the plants look just like my plant.

My plant arrived as a slim tuber and one shoot grew, split into two, these fell apart and continued to grow and new shoots have grown from the top of the tuber. I planted it too near the surface but I was worried about rot. It is now growing well and lots of flowers are being produced. It is supposed to be free-flowering, over many months. It is also reputed to tolerate a bit of frost. It should survive air temperatures of -5c if the tuber is below the soil surface. The habit is just like C. atrosanguineus.

The question I now need to ask is whether it is worth the effort since annual cosmos are so easy to grow, and actually self seed in the garden. The flowers are subtly different to annual cosmos, and the leaves are very different. It is nice but if I can’t keep it I won’t be in a hurry to replace it. I am not hoping it will die and I will do my best with it but the annuals are so good – and much less expensive. Perhaps I will collect seeds and see what appears among the seedlings. There may be some good things. My plant is in a pot with purple-leaved oxalis (ridiculously easy to grow and propagate) and some isotomas which should become covered in pale blue stars when they finally make the effort – they are really slow from seed!

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