Heliotrope

The common name tells you everything: cherry pie plant. Lean in close to a heliotrope in warm sunshine and the scent is extraordinary — a rich, sweet, vanillin warmth that genuinely does smell like cherry pie, or maybe marzipan, or warm almonds, or all three simultaneously. It's one of the most delicious fragrances in the plant world, and it comes from a flower that most people walk past without a second glance.

'Marine' is the variety you'll find most easily — compact, well-behaved, with dense, domed clusters of tiny flowers in a deep violet-purple so dark it borders on navy. The colour alone would be worth growing it for, but it's the scent that earns heliotrope its place. The Victorians understood this — they grew heliotropes obsessively, as bedding, as standards, as pot plants for conservatories. Then somehow we forgot about them.

I grow mine in pots by the back door, where the warmth of the paving intensifies the scent. On a hot afternoon, sitting outside with a cup of tea and that cherry-almond fragrance drifting over — that's a very specific kind of happiness. The dark purple flowers against the deep green, slightly textured leaves look handsome in a serious, old-fashioned way.

They're tender perennials treated as annuals in Britain, which means you start fresh each year or take cuttings before the frost. The effort is worth it. Once you've smelled a heliotrope properly — properly, with your nose in the flower in full sun — you won't forget it. Some scents are like that. They write themselves into your memory and stay.