Azaleas of different color

WASHINGTON – As the high water of magenta and pink azaleas begins to recede from around our homes – our annual red tide? – it may be a good moment to consider the daintier, less common and differently colored deciduous azalea now on the verge of making a much-deserved comeback.

Gardeners of a certain age recall these treelike azaleas for their own strong hues, including shades of orange not seen in the common hybrid evergreen azalea, and wonder how a shrub with such starkness could remain so stately. The answer lay in its habit, as an upright and layered tall shrub, not as the dense mounds of evergreen foliage more typically used here. Among other advantages, the warm orange and golden yellow blooms of the deciduous article could be used to dramatic effect, especially contrasted with some of the many blue-flowering perennials available in mid-spring, including squill, woodland phlox and bearded irises.

Most of these older varieties were created from complicated breeding programs in the 19th and early 20th centuries in Holland, Belgium and England, most notably in England by the nurseryman Anthony Waterer at his Knap Hill nursery and by Lionel de Rothschild at his garden at Exbury.

Some varieties fare well in warmer climates – for example, Gibraltar and Marina, if you can find them. Others struggle in the heat. The farther south you go, the more these hybrids fall like flies, stressed and prone to powdery mildew.

Now, however, gardeners are the happy beneficiaries of efforts to make these older plants better suited to warmer regions of the United States while remaining hardy at least as far north as New York.

Eugene Aromi was an art professor at the University of South Alabama whose avocation was the development of better azaleas. After trying his hand at evergreen forms, he sought to invent a better deciduous azalea, using as parents native azaleas that thrive in the wild in the hot South and crossing them with “just about every Exbury (variety) you can think of,” said Maarten van der Giessen, a nurseryman in Semmes, Ala., who worked with Aromi and inherited his collection of azalea hybrid seedlings after the professor died last year.

In trying to find more bulletproof varieties, species native to the Southern United States are an obvious place to start. The Florida azalea (Rhododendron austrinum) variously blooms yellow to golden orange just as the leaves begin to emerge. The coastal azalea (R. atlanticum) is low-growing with fragrant pink blossoms. The highly variable flame azalea (R. calendulaceum) has flowers of yellow, red, pink or orange in late spring. The Piedmont azalea (R. canescens) is a tall shrub with pink and white flowers that are sweetly fragrant.

Aromi made a total of 1,045 crosses, each producing dozens of individual seedlings. He whittled these down to 109 named varieties that were raised and propagated by horticulturists who took up his cause, namely the late John Allen Smith in Mobile, Ala.; his colleague Linda Guy, now of Carolina Nurseries in Charleston, S.C.; and van der Giessen.

While van der Giessen works on some of Aromi’s later introductions, Guy’s nursery has 15 currently in wholesale production. The first four – Sunny Side Up, Sunset, Sunrise and Pink Carousel – are among them and commonly can be found in retail nurseries and at Lowe’s and Home Depot.

Other native azalea seedling selections and hybrids are also making their way into the trade and to consumers, though a bit of Internet surfing may be necessary to turn up retail sources. These include ‘Choice Cream,’ a small shrub with fragrant, lemon yellow flower trusses; ‘Snowbird,’ a fragrant white bloomer with a compact habit; and ‘White Lightning,’ a selection of the sweet azalea.

For Linda Guy and Maarten van der Giessen, it is the prospect of more of Aromi’s selections reaching the public in years to come that has them most excited.

“We haven’t scratched the surface,” said van der Giessen. Aromi “has in some ways surpassed anything Rothschild ever dreamed of, which is astonishing.”