I’ve been taking look round the delightful garden at Yew Dell, just outside Louisville, Kentucky, in preparation for the American Horticultural Society’s Garden School which opens there today. And I came across one of the most striking new perennials to be introduced in recent years.

‘Low Down’ is a very dwarf and very prolific form of a huge perennial, Helianthus salicifolius, which can reach 10ft/3m in height. At Yew Dell’, ‘Low Down’ reached little more than 15in/38cm and is covered in brilliant yellow daises.

‘Low Down’ was raised by one of the world’s finest plant breeders, Dr Keith Hammett from New Zealand. He’s also produced some superb sweet peas, wonderful yellow clivias and many fine dahlias as well as other plants. Look out for ‘Low Down’, and for its sisters ‘First Light’ and ‘Table Mountain’ in mail order catalogs and nurseries.

Often listed under H. angustifolius, Dr Hammett tells me they are, in fact, forms of H. salicifolius – as the slender foliage indicates. All three are well worth growing.