Star Gardener: Expert’s Choices

Tom Ranney is perhaps best known for his research on calycanthus (sweetshrub) hybrids
Magnolia R-20-1 is a hybrid that one enthusiast dubbed the greatest of all magnolia crosses. Tom Ranney

   The plants a professional selects for his own home garden are worthy of a close look. When that professional heads a research program that develops, evaluates and selects new trees and shrubs for introduction, his personal choices are worth at least two looks and the beginning of a search to obtain them.
    Tom Ranney is perhaps best known for his research on calycanthus (sweetshrub) hybrids, especially Calycanthus Venus, with its large white blossoms and maroon centers. He is a professor at North Carolina State University and heads the woody plant research program at Mountain Horticultural Crops Research Center in Mills River, N.C.
    Dr. Ranney’s presentation at the Woody Plant Conference in Villanova, Pa., two weeks ago had many in the audience furiously taking notes. The plants that captured my interest include two evergreen shrubs: a mahonia and a dwarf anise tree. A new compact clethra sounds very good and it was gratifying to learn Fothergilla Blue Shadow, which is growing in the Mimi Meehan Native Plant Garden, is destined for greatness. If I had a larger property, or my garden were less heavily planted, a hybrid magnolia he recommends would be on my must-get plant list.
    Mahonias have a lot going for them. They are, so far, deer resistant, have dark green, glossy leaves, do well in shade, and flower in the winter. On the downside, they need to be protected against wind, can suffer from wind damage in winter, and their flowers can be blasted by a drop in temperature. 
    In the past two decades a number of species from China have been introduced by Dan Hinkley and others. British breeders, as well as Dr. Ranney, are conducting hybridizing programs, and Dr. Ranney predicts a range of very good garden plants will result over the next 10 years. As a mark of confidence, his first release has been named for the legendary North Carolina State horticulturist J.C. Raulston, a mahonia enthusiast. It has plumes of showy yellow fragrant flowers in late winter. It may take a few years before it is readily available, but put it on your wish list. Other mahonia hybrids will have red flowers and white coatings under dark green leaves.
    Here in East Hampton we are at the northerly end of the range of the Florida anise tree, Illicium floridanum, an evergreen shrub that has highly aromatic, lustrous dark leaves and maroon flowers that resemble little comets. The cultivar Woodlander’s Ruby, about eight feet high, has two flushes of flowers, thrives in deep shade, and has been a valuable addition to my winter garden for 10 years or more. Dr. Ranney’s group is introducing a dwarf groundcover illicium named Swamp Hobbit that was discovered growing in Alabama. Its leaves and flowers are the normal size, but after five years it is only eight inches high by a foot across.  An evergreen, deer-resistant groundcover for shade, it should have a bright future.
    Summersweet, Clethra alnifolia, is not particularly deer resistant, but nonetheless has been flowering profusely and fragrantly since mid-July along damp roadsides in East Hampton and Montauk, as well as in our gardens. Thanks to the variability of summersweet, named selections are available in shades of white and pink, different blooming times, and height.
    Crystalina, a very compact rounded shrub released by Dr. Ranney that matures to about three feet high and has long racemes of flowers, is said to be a big improvement, needing little pruning over the years. It is widely available in garden centers and by mail order. For some reason I keep envisioning Crystalina as a soft flowering companion to the ubiquitous, severely clipped spheres of boxwood that have taken over our landscape recently as garden designers attempt to outfox the deer. 
    As an aside, I am having success with another, taller clethra, the late-blooming Anne Bidwell. It has clusters of upright spires that open gradually to large flowers. Early in its blooming cycle, the spires have a lacy look because of the large buds, but when mature will be dense and showy.
    The hybrid shrub Fothergilla Blue Shadow is one of the more garden-worthy of the family. Its steel blue foliage persists when grown in shade and it is supposed to have good autumn foliage. I came across it in May and planted it toward the rear of the Native Plant Garden as a focal point with blue-leaved perennials. Dr. Ranney is not alone in proclaiming its virtues and good garden performance; it is sure to become a classic.
    Anticipating a new group of magnolia hybrids, Dr. Ranney singled out one that has not been given a cultivar name yet, Magnolia R-20-1. A cross between the oriental M. sieboldii and the native large-leaf magnolia, M. macrophylla ssp. ashei, R-20-1 has upright white flowers up to eight inches across with a ring of red stamens in the center combined with the exotic tropical-looking large leaves of its native parent. One magnolia aficionado has dubbed it one of the greatest of all magnolia hybrids. It is offered by Rare Find Nursery in New Jersey and Broken Arrow in Connecticut.
     Learning about some of the best new plants becoming available in a cool and comfortable hall was a pretty good and productive way to spend a hot, humid summer day.