Rhododendron x kosterana x prinophyllum

This hardy hybrid azalea is a piece of Woodlanders history, a deliberate cross made by the nursery's late founder, Robert Mackintosh. Mackintosh crossed the native roseshell azalea, Rhododendron prinophyllum, with the old hybrid group known as R. x kosterana, or mollis azalea, and the result is an upright, large-flowered deciduous shrub carrying bold orange trusses each marked with a splash of yellow.

The parentage is worth telling in full, because the lineage spans three continents. The roseshell azalea is one of the most northerly and most fragrant of the American natives, a rosy-pink shrub of New England and the higher Appalachians famous for a strong cinnamon-and-clove scent. The mollis side reaches farther afield: R. x kosterana is itself a cross of the Japanese azalea, Rhododendron japonicum, with the Chinese Rhododendron molle, a parentage that lends the hot orange and yellow coloring and the large flower size. Blending a hardy, fragrant American parent with the vivid color of the Asian mollis azaleas is exactly the kind of cross a plantsman makes to get the best of both.

The flowers open in spring on an upright frame of four to eight feet, large and showy, glowing orange with a gold flare at the throat, and set off against fresh green deciduous leaves. Early bees and butterflies work the trusses. As with every azalea, the whole plant carries grayanotoxins and is poisonous if eaten, so the shrub is one to grow for the spring show and keep clear of children and livestock.

Grow the hybrid as other native and deciduous azaleas are grown: in the high, filtered shade of tall pines, at a woodland edge, or in a mixed border, where the vivid spring color can carry across the garden. Give cool, moist, acidic, well-drained soil, mulch the shallow roots with pine straw, and pair with fragrant pink and white native azaleas so the hot orange has something cool to play against. A hardy, characterful cross with a genuine Woodlanders story behind the plant.