What Are Azaleas For Connoisseurs?

A full four months of azalea bloom may sound like a gardener’s tall tale. But it becomes a fact when there is a discriminating choice of native azalea species to provide a season of bloom extending from April through August – a claim unchallenged by the new hybrids.

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These rare and delightful American species have been admired and beloved abroad but never properly appreciated here. However, their offspring—the spectacular new azalea hybrids from Exbury and Knap Hill, in England, and from Ham, in New Zealand, will undoubtedly become familiar in the garden scene. 

Now several specialized nurseries here, at last, recognizing the possibilities of our native azaleas, have started to offer them to the public.

Foreign Hybrid Azaleas

The foreign hybrid azaleas are flamboyant with their enormous blossoms, but the American species from which they are derived are works of art. 

Modeled by nature to even greater beauty, they possess a subtle balance between the size of flowers and leaves, breadth of branches, and overall plant stature, which the new hybrids entirely lack. 

Though the blossoms are smaller, those of many species are so generously borne that they are just as colorful as the hybrids.

These peerless plants – our native azaleas – are sophisticated rhododendrons that have been obliged to shed their leaves in winter to survive. But rhododendrons they are, with species names preceded by the letter R to indicate their kinship to the evergreen ancestors from which they evolved.

Rhododendron Austrinum And Rhododendron Canescens

The first of these shrubs to bloom are R. austrinum and R. canescens. The delicate yellow, orange-red, or ivory blossoms of the former combine beautifully with the pink-to-white flowers of the latter. 

Both species have a delightful spice-like scent, ultimately reaching 10’ feet in height. They are hardy to Philadelphia and beyond—although the vicinity of New York City probably represents the northern limits of their reliability.

Rhododendron Vaseyi

The beautiful and unusual R. vaseyi is next to blossom in early May. A rugged, adaptable shrub that is hardy to 25° degrees Fahrenheit below zero, its flowers open at just the right time to form a backdrop for a multitude of wildflowers. 

The large blossoms which cover the plant are borne with jaunty grace. Although this species is usually pale pink, some lovely deep pink shades may be selected at the nursery when it is in bloom, and a form with large glistening white blossoms is now on the market. 

One with remarkable crimson, velvet-textured flowers is being propagated for early introduction.

A trio of azalea species, which equal R. vaseyi in exceptional landscaping value, bloom in mid-May. These three make a stunning display when:

• The dwarf pink to ‘white-flowered R. atlanticum is used in the foreground

• The 4-foot R. alabamense with shimmering white, pale yellow, or pink blossoms behind it

• And the tall pink R. roseum at the rear. 

Added to this choir of color is the fragrance of roses, oriental lilies, and cloves, which emanate from the three species, each in the order named.

Rhododendron Roseum

All three species thrive around New York City, but farther north R. alabamense must be omitted, and beyond Boston, only R. roseum is likely to flourish. 

An alternative for R. roseum is R. nudiflorum, similar in appearance but not as desirable either in its fragrance or in the modeling of its blossoms. 

Gardeners are often puzzled as to which of these azaleas they own, and reference books are none too helpful. 

However, the dormant floral buds are easily distinguished—those of R. roseum are hairy, while those of R. nudiflorum are smooth. Both species are hardy to 25° degrees Fahrenheit below zero.

Rhododendron Canadense

Also about mid-May, an odd little dwarf azalea with small but numerous blossoms comes along to enliven the garden scene. It is R. canadense, the hardiest of all the native species.

Atop 15-inch stems, flowers appear in pinkish lavender, sometimes labeled magenta and therefore disliked. 

A white form can be found at a few nurseries for gardeners who object to the usual flower color but appreciate the distinctive blue-green foliage. Finally, a cupful of sulfur scattered over a square yard of the same soil that pleases other azaleas will ensure the contentment of R. canadense.

Rhododendron Calendulaceum And Rhododendron Speciosum

R. calendulaceum and R. speciosum are the next stellar performers in the azalea garden. The former, Flame azalea, is perhaps the best-known native species. 

It is radiantly effective when the 2-inch blossoms open in shades of orange, yellow, red, pink, and every conceivable blending of these colors. 

In my estimation, the selected forms of this species are superior to the high-priced and often unsatisfactory grafted Ghent hybrid azaleas. 

R. calendulaceum, which is hardy to 25° degrees Fahrenheit below zero, reaches 10’ feet or more in height; its close relative, R. speciosum, is more modest in stature (about 5’ feet) and blossoms, though scarcely less beautiful because of its delicate appearance. 

With a skillful selection of colors, R. calendulaceum and R. speciosum are good companions as far north as New York City. In colder climates, the latter is of doubtful hardiness.

Rhododendron Occidentale 

Following the extraordinary performance of the Flame azalea in late May comes that of two azalea species—R. occidentale and R. oblongifolium. Although all specialists would like to grow these, few have succeeded with them in the East. 

R. occidentale, the lovely white to light pink scented azalea native to the West Coast, seems to be winter hardy, at least as far north as Washington, D. C., but it does not take to our hot summers. 

Among the finest of the native species, it is well worth a trial in the Washington-Baltimore area and southward.

Rhododendron Oblongifolium

The other difficult azalea, R. oblongifolium, with sweetly fragrant white flowers, is from Arkansas and Texas. I grow this rare species in pots because it could scarcely be expected to survive 25° below zero in northwestern Pennsylvania winters. 

Unprotected, it has failed in a few trials along the East Coast. However, plants of R. oblongifolium are thriving in Richmond, Va., in the collection of native azaleas at the Biltmore Estate near Asheville, N. C.

Rhododendron Cumberlandense

Next, in late June, comes R. cumberlandense, a species of ironclad hardiness in the brightest raiment of all the azalea clan. It is a sentinel of fire lighting up the landscape like a torch of glowing red embers. 

The remarkable incandescent scarlet blossoms together with the dense, compact branching and good foliage held to the ‘end of the season, make this, in my opinion, the finest of the native species.

Rhododendron Furbishii And Rhododendron Bakeri

Marking the end of June and the beginning of July are three species that stage an unrivaled show at a season when most woody plants have finished their annual display. 

The medley of harmonics and contrasts is like a renewal of springtime when a group of white R. arborescens, pink R. furbishii, and yellow to orange-red R. bakeri is in bloom. 

The R. arborescens goes in the background, R. bakeri in front of it, and R. furbishii, which reaches an ultimate height of about 6’ feet, is best placed in the foreground. 

The first of the trio has the compelling fragrance of heliotrope, and the last makes an exceptionally fine-cut flower reminiscent of orchids. All three are hardy to 25° degrees Fahrenheit below zero.

Rhododendron Viscosum

Just a little later, the white, clover-scented blossoms of R. viscosum open. Of ironclad hardiness, this species is not as spectacular as its earlier cousins, but it is easily pleased and a welcome addition to the limited number of shrubs in flower at that time.

Rhododendron Serrulatum And Rhododendron Prunifolium

In August R. serrulatum and R. prunifolium bring the four-month azalea parade to an end. The former is a larger-blooming edition of R. viscosum, though hardly only to New York City. The latter is certainly the most valuable and neglected shrub available to gardeners in this country. 

Just as the leaves begin to look tired and the lawn has lost its springtime luster, this azalea bursts forth with a gaiety and sparkle that lights up the garden and lifts the spirits. It is jeweled with flowers of a vibrant red— more rarely yellow or orange. 

Hardy to New York City, but needing more moisture than its relatives, it is known only to four or five specialists here in the East. Surely it is. will be discovered someday by alert gardeners.

Azaleas In Georgia

Some species of native azaleas are found only in limited areas of Georgia. North Carolina and Alabama, but where a choice exists, gardeners should try to obtain plants native to their locale. 

Plants purchased from a collector who gathers them from the wild should be cut back after planting within 4” inches of the ground. Again, nursery-grown plants are the better choice if available.

An open situation with shade during the hottest part of the day is ideal. Few gardeners can offer perfect conditions, but fortunately, the native azaleas are adaptable. However, they will not thrive in dense shade.

Grow Azaleas in Alkaline Soil

Only a few gardeners have dared to grow native azaleas in the naturally alkaline soils of the Midwest. 

If the new agricultural fruits (containing magnesium, iron, and other trace elements) are incorporated into the ground, acidity may lose its importance for azaleas and rhododendrons so that they may be grown almost anywhere in the country. 

It is a promising prospect that may be confirmed by gardeners who are willing to experiment.

44659 by David B. Leach