Native Azaleas for Northern States
From "The Green Mountain Grower" No. 86, November 77
Dr. N. E. Pellett, Editor
Dept. of Plant and Soil Science
University of Vermont, Burlington, Vermont
Several deciduous azaleas native to the eastern United States have potential for wide landscape use in Vermont. Rhododendron roseum, popularly known Mountain Pink is native in southern regions of Vermont, occurring as far north as Johnson. Admirers familiar with its colorful pink flowers often ask nurserymen for this plant. Unfortunately it is not commonly available in the trade. Other native deciduous Rhododendron species potentially useful in Vermont include flame azalea, R. calendulaceum; swamp azalea, R. viscosum; pinkshell azalea, R. vaseyi; rhodora, R. canadense and R. arborescens. The Vermont Agricultural Experiment Station has received a grant from the U. S. D. A. Plant Introduction Station to collect native azaleas and rhododendrons with potential for cold regions. Seeds or superior selections of eastern species are being collected from native stands in the northernmost or coldest part of their range.
Small samples of seed are available to experiment stations, Arboreta and Vermont nurserymen. Seeds available now include:
Rhododendron roseum from Lake Dunmor near Brandon.
R. viscosum from near Amherst, Mass.
R. canadense from near Island Pond.
Kalmia latifolia from near Brattleboro.
The following procedure is recommended for seed propagation of native azaleas:
January - Start seeds under fluorescent lights (16 hr day). Sow seeds on pressed surface of pre-moistened shredded sphagnum moss. Carefully sprinkle with water. Cover with polyethylene or glass and put under lights at 70°F. When seeds germinate remove cover & plant so plants are within 6" of lights. As plants develop, fertilize regularly with a dilute fertilizer solution (i.e., ½ tsp of Rapid-gro in 1 gallon at every watering). Plants can be grown in the greenhouse, but plants need long days to continue growth.
March - When seedlings range from 1 to 2" tall, transplant into individual pots or flats. The following soil media has given good results:
peat; perlite 1:1, per cubic ft. of soil, mix in:
Gypsum, 3 tablespoons Epsom salts, 3.5 teaspoons
Fritted trace elements, ½ tsp.
Continue to fertilize plants regularly.
If they show chlorotic foliage, use an acid-reacting fertilizer. Pinching the terminal of new growth will promote branching.
June - Plants should be six inches tall, branched and ready to line out in field rows or grown on as container plants out-of-doors. Plants should be saleable the following spring.