Notes on Rhododendrons in Indianapolis
By Hurt F. Panzer, Indianapolis, Ind.
I have been growing rhododendrons and azaleas in Indianapolis for approximately twenty years. I have specialized much more in the azaleas because they bloom every year, whereas the rhododendrons at most bloom in alternate years although I find myself lucky to get a good stand of bloom out of the R. maximum every three or four years.
The hardiest variety of azaleas for Marion County, according to my experience, is Azalea kaempferi. The plants seem never to kill and rarely are the flower buds injured by a cold, icy winter such as the one we are now experiencing. Next in hardiness comes the kaempferi hybrid 'Arnoldiana' (the result of crossing kaempferi and 'Amoena') in its four varieties: 'Briarcliff', 'Early Dawn', 'Mello-glo' and 'Mossieana'. I have a hedge of these. Provided there is sufficient sunshine, they bud well and the slightly varying pastel shades of the four varieties create a color-rhythm which I have never seen duplicated in a flower garden.
Next in hardiness come the kaempferi hybrid azaleas (the result of crossing R. kaempferi and R. 'Malvatica'.) The ones which I have found most hardy in my garden, in the order of hardiness, are 'Purple King', 'Alice', 'Mary', 'Betty', 'Zampa', 'Gretchen', 'Fedora', 'Cleopatra', and, least hardy of all, 'Mikado', 'Carmen' and 'Atalanta' have died on me repeatedly. It is to be kept in mind that 'Purple King' blooms about five to six days later than the others.
Among the Kurume azaleas, 'Amoena Coccinea' and 'Hinodegiri' have been fairly hardy. The lovely soft pink 'Hinomayo' is very subject to winter kill. Although I have repeatedly tried the Gable Azaleas, my efforts have not been attended with much success.
Among miscellaneous azaleas, I find that R. mucronulatum sports its lovely lavender blooms at the time the Forsythia bloom with great regularity, withstanding many early April snows. A number of Indica Roseas bloom for me every year. 'Indica Alba' is not nearly so hardy. R. 'Yodogawa', a very late blooming double, purplish-pink, is quite hardy.
As for the deciduous American azaleas, calendulacea and R. vaseyi are the only hardy ones. I have not had much luck with roseum, R. arboresens or R. pontica.
Among the rhododendrons, of course, the ordinary R. maximum does the best. About every three to four years the bushes bloom their heads off and then it takes several years to build up to a maximum bloom again. The first year after a R. maximum blooms there are practically no buds. Rhododendron catawbiense (non-hybrid) generally dies after three or four years. Among the hybrid R. catawbiense varieties I find 'Roseum Elegans', 'Grandiflorum', 'Cynthia' and 'Ignatius Sargent' the best. I rarely lose any R. maximum or R. catawbiense flower buds in the winter.
Last winter I made one of those "noble experiments" such as I suppose every garden-lover feels it an obligation to perform before he dies. My experiment consisted of placing eight to ten ounce burlap tents over my azalea beds so as to protect the buds from winter kill. It was my theory that zero and subzero weather was not nearly so dangerous to the buds as an accumulation of ice upon them which "burnt" them when the sun began to thaw. The experiment was performed not merely with respect to azalea buds but also wisteria buds (which are very subject to spring kill by ice), Chinese magnolia buds and the buds of Paulownia tomentosa. The weather was very cold but we had no snow or ice whatever; consequently, the experiment was negative. However, I never had a finer bloom of azaleas and wisteria in the twenty years of my experience.
This year the experiment with burlap is again being performed with much more chance of determining whether the burlap is of any help to the buds. We have had nothing but snow-ice and zero weather. A very large percentage of the azalea buds has come through the winter green to the core. In the case of 'Amoena Coccinea' and 'Cleopatra', however, the experiment does not seem to have worked. So far, there is no sign of any winter killing in the case of the wisteria buds. All my forsythia buds (none of which were covered with burlap) have been completely killed.