JARS v50n3 - Tales of a Reluctant Bloomer

Tales of a Reluctant Bloomer
Leo J. Sandmann
Trumbull, Connecticut

As an admirer and collector of multi-colored and blotched rhododendrons living in coastal Connecticut, USDA Zone 6b, I was impressed when I first saw 'Todmorden' in bloom at Planting Fields Arboretum on Long Island. In 1986, with great anticipation, I obtained a 1-foot high specimen. Five years later, the plant was 4 feet tall and I was still waiting for bud formation. Frustrated, I moved it to a sunnier location and was rewarded the following year with an abundance of flowers, but there was no bud formation for the next two years. In the spring of 1994, thinking that my garden might be receiving too much shade, a tall tulip tree, standing about 20 feet away on the south side of the plant, was removed. By now the plant was 5 feet tall and had more than 100 terminal branches.
At the same time, I discussed the situation with Dr. Gustav Mehlquist who suggested constricting the main branches with a rubber band to keep nutrients in the terminal growth. Dr. Mehlquist mentioned that this was an old trick used by nurserymen, but I had not seen mention of it in an ARS publication.
I tightly wrapped a -inch rubber band about the base of one of the main branches but left the others unwrapped to see the difference, since I did not want any possible bud formation attributed only to increased sunlight from the tree removal. The results were significant: there were 49 terminal branches on the wrapped stem with buds on 40 percent. The 75 terminal branches on the unwrapped stems had only 21 percent formation. The rubber band was removed in the fall.

R. 'Todmorden'
'Todmorden' with red band showing branch wrapped with rubber band.
Photo by Leo J. Sandmann

Fortunately, the winter was mild and the plant put on its best display ever in 1995. Wishfully thinking 'Todmorden' was ready to mend its erratic ways, no wrapping was done during the 1995 growth season. After nine years it had obtained a height of 6'6" but returned to its parsimonious habit with only 5 percent bud formation on each of the main branches.
The only conclusion I could reach was that if this temperamental plant had in its mind to bloom, banding could make some difference. As for next year, some severe pruning is in store to curb its leggy growth.

Leo Sandmann, a retired engineer, is a member of the Connecticut and New York chapters.