Phlox

I didn't used to think much about phlox — it was just one of those background plants in other people's gardens, pleasant enough but not particularly exciting. Then I grew 'Blue Paradise' and had to completely revise my opinion.

The colour is extraordinary. It opens a rich violet-blue that shifts and changes depending on the light — sometimes leaning towards purple, sometimes towards a true, clear blue, and in evening light taking on an almost luminous, electric quality. No photograph I've taken has ever quite captured it. It's one of those colours you have to see with your own eyes.

But it's the scent that really converted me. Phlox has this warm, honeyed fragrance that fills a whole section of the garden on a still summer evening. 'Blue Paradise' carries it strongly — stand downwind of a mature clump on a warm July evening and it's almost as heady as the sweet peas.

As a cut flower, it's generous. The flower heads are big enough to make an impact on their own, and they last well in a vase — a good week, often more. Mix them with white garden roses and some trailing greenery and you've got something that looks expensive and smells even better. They flower from July well into September, which gives you weeks of material for the house.