The Glenn Dale Hybrid Azaleas launched in a cannonade of almost unparalleled publicity years ago.
A sensation at the big flower shows, they were the talk of horticultural circles throughout the country.
Garden writers in the US and abroad paid them such glowing tribute that the supply of available plants vanished overnight. Any azalea with a Glenn Dale label was eagerly purchased.
Today, the Glenn Dale azaleas are suffering from a hang-over of misunderstanding, confusion, and abuse.
Their neglect is depriving gardeners of some of the finest achievements of the plant breeders’ art.
Let us see why the Glenn Dale hybrids as a group have failed to achieve the popularity of their early promise.
Glenn Dale Hybrid Azalea’s Many Varieties
Glenn Dale hybrid azaleas are the type whose leaves persist over winter, a popular attribute with gardeners from Boston far into the Deep South.
They are the creation of B. Y. Morrison, former head of the United States Plant Introduction Garden at Glenn Dale, Maryland.
In an article, Mr. Morrison described his splendid goal for the enrichment of gardens in intermediate climates, such as that of the Washington, D. C., area, when he selected 450 varieties from 75,000 seedlings grown from his crosses.
Practically all specialists now sorrowfully agree that far too many similar varieties were introduced and varied widely in garden value.
Mr. Morrison has pointed out that less than 1% percent of the seedlings were selected for commercial introduction.
He has implied that he expects the list of varieties that bloom at different seasons to be reduced by testing locally adaptable ones in various districts.
However, the unfortunate short-range effect has been that professional growers and home gardeners alike have foundered in a sea of almost 500 different sorts.
The hardy types have been confused with the tender ones. Those who lack vigor in some regions have given their reputation to those who have abundant vigor.
The varieties which have good foliage have never been tried because others have failed to please.
Declining Of Glenn Dale Azaleas Propagation
Typical now is the procedure of the largest commercial producer of Glenn Dale azaleas in the capital district, reducing his listings to a manageable 50 of the best of the 450 introduced initially.
Unfortunately, some Glenn Dale azaleas have not been hardy even in the Washington region.
In New Jersey, where most of the East’s largest azalea nurseries are concentrated, many of the leading wholesale producers have declined to propagate the Glenn Dales because they are not satisfied with their hardiness.
But anyone who sees the magnificent performance of these azaleas at famed Longwood Gardens near Philadelphia, in private gardens in northeastern New Jersey, and even in Connecticut is soon searching for an answer to the apparent contradiction.
It may be that those of borderline hardiness become unsatisfactory only when they are subjected to growth-forcing necessary to produce plants quickly in commercial nurseries.
Farther north, the apparent contradiction lies, perhaps, in a combination of injudicious fertilizing and the natural lack of cold resistance, which is characteristic of very young plants, as the hardiness of specimens several years old in private gardens is known.
The Glenn Dale azaleas were not intended for a climate more severe than that of Washington, D. C., and those which prove hardy farther north can be considered an unearned bonus.
Public’s Great Favorite Pink Azaleas
Pink azaleas are great favorites with the public. The Glenn Dale group is not particularly strong in this color, but a few outstanding ones are achieving prominence.
They are the following:
- Dayspring has already become a classic with its unusual blossoms shading from white in the center to pink margins. It is one of the few early-blooming Glenn Dales and one of the very best.
- Joya and Fashion, the latter with hose-in-hose flowers.
- The season for pink continues with Martha Hitchcock, which has unique reddish-purple margined flowers with white centers which are 3” inches in diameter and give a pink garden effect.
- Crinoline is one of the best of all the Glenn Dales, with ruffled Tyrian-pink blossoms which flare out even wider than 3” inches.
- Lillie Maude is almost a duplicate of Crinoline but blooms about two weeks later.
- Saga is the best of the late-blooming pinks, with 3-inch, fringed flowers on a low, spreading bush that matures to 3’ feet.
3 Varieties Of Deep Rose Pink Azaleas
The deeper shades of rose pink are also popular, and there are 3 varieties in this group on which there is general agreement as to their outstanding qualities.
They are:
- Suwanee comes first (in mid-season), and it is one of the most luminous stars in the constellation of fine Glenn Dale hybrids, with bright, crisp flowers 3” inches across.
- Pearl Bradford and Sagittarius (two late-season sorts)—the first deep rose-pink, the latter salmon-pink. Both are of extraordinary value for their low, 2-foot stature. The blossoms are 3” inches.
Glenn Dales In Purple Or Lilac Shades
The Glenn Dales are outstanding in shades of lilac to purple, and I hope that gardeners will hold in abeyance their prejudice against this color range until they have seen these stunning hybrids.
The varieties are:
- Content, a good one with 3-inch blossoms of pale purple in mid-season.
- Zulu overshadows Content with even larger flowers of sleek, rich mallow purple.
- Nocturne with big, aster-purple flowers of remarkable brilliance. It seems inevitable to become a universal favorite.
- Youth is another of the truly glorious hybrids with fragrant purple flowers.
Red-Flowered Glenn Dale Hybrids
The red-flowered Glenn Dale hybrids are noteworthy for their purity of tone, but, like almost all azaleas of their color, they bleach in the sun, and they should have some protection, especially at midday, if it can be arranged.
They are the following:
- Redbird makes a splash of pure scarlet in early midseason.
- Galathea, in a shade of red, is not too different, which is also notable for the luminous burnish of its blossoms.
- Copperman is the chief of the red-flowered group, a flaming achievement with 3-inch flowers of glittering purity which come in late midseason.
White-Flowered Glenn Dale Hybrids
The white-flowered hybrids are azaleas of triumphant fairness, with an elegance of unadorned beauty that beggars description.
If no other Glenn Dale azaleas existed, these alone would make their name secure in the annals of horticulture.
Here are the white-flowered varieties:
- Glacier is regarded by many specialists as the finest in the entire hybrid group, combining as it does large white flowers of immaculate purity with lustrous, dense foliage, which would be extraordinarily handsome if there were never any blossoms.
- My favorite is Treasure, which also blooms at mid-season. It has huge, opulent blossoms that open from blush pink buds and retain a hint of flush to warm their whiteness.
Hardy Glenn Dale Hybrids
How hardy are these Glenn Dale hybrids which are here recommended?
They are among the hardiest and most adaptable of this entire race of azaleas. Still, no one can give positive assurance that they will thrive in any specific situation north of Philadelphia.
Gardeners experienced with the Glenn Dale hybrids agree that they thrive best with some shelter, as in the high dappled shade from hardwood trees and on the north and northeast sides of buildings and evergreens. Their growth should not be forced.
An application of cottonseed meal in April and again in mid-June, but not later, is ample.
They should not be irrigated after mid-August so their tissues will safely harden before the advent of cold weather.
Like all azaleas, they require acid soil that is loose and porous in texture and liberally fortified with peat or other humus.