Nigella 'Miss Jekyll' White (Love-in-a-mist)

The white form, and from any distance a drift of it reads as low-lying cloud or sea foam rather than as a group of flowers. Semi-double white blooms held inside the same ruff of thread-fine green foliage.

White does a specific job here. Against strong colour it acts as a bright neutral and makes reds, blues and purples read more vividly, and in a moon garden or an evening border it holds light when everything else goes flat.

The seed pods are as good as the flowers. Each spent bloom swells into a striped balloon that stands through autumn and dries for a winter arrangement, and the black seeds inside are kalonji, the peppery black cumin of Indian and Middle Eastern kitchens. Deadhead for a longer flowering season or leave them for pods; you have to pick one.

Sow it where it is to grow, because the taproot resents transplanting, and sow in September for earlier, stronger plants. Keep it lean; rich ground gives foliage instead of flowers. It self-seeds prolifically, and near blue nigella the seedlings come back blue within a couple of generations.