Chocolate Cosmos

When it was called Bidens atrosanguinea this plant was comparatively unknown, but in the past couple of years, this tender Mexican perennial has become an ultra-fashionable late summer highlight in warm borders – what a difference a name makes! It’s grown, more for its scent of vanilla and hot chocolate than for the dusky brownish-red blooms – pretty as they are.

As with most cosmos varieties, the blooms resemble small single dahlias, and its culture is similar too, for it has a tuber which, in mild gardens, may be planted at least 15cm (6in) deep and left in the ground with winter protection, or in very damp or very cold regions – or in gardens with a squirrel problem (squirrels love these tubers, which must have the same wonderful smell to them as the flowers have to us!) - lifted in autumn for drying and storage.

Please be aware that if you come across it on your holidays, chocolate cosmos is endangered in the wild and should not be picked or dug up. However, transplants (home grown plants from original tubers, not imported ones) are easily found at most nurseries and garden centres in the spring. Plant chocolate cosmos in organically rich, well-drained soil in a location that gets full sun. Keep the transplants moist until they established roots and you see the beginnings of some new growth; the blooms appear from June through September, broadcasting a beguiling chocolaty scent late in the day and are very attractive to butterflies. In autumn, when foliage dies back, cut plants down to about two inches from the root and over-winter them in a frost-free area.

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