If I wanted to, I could fill the entire yard with roses of Sharon. So could most people, because roses of Sharon, or Hibiscus syriacus, are among the most prolific garden shrubs. All you need to launch a rose of Sharon world domination campaign is one small specimen anywhere on or near your property. If it flowers, its alluring blossoms will be pollinated by obliging insects. After pollination, it will produce fat green pods full of viable seeds. When I say “viable,” I mean that one hundred and ten percent of the seeds will germinate. The resulting seedlings will grow at lightning speed and make a priority of producing flowers of their own. Nature will take its course and without human intervention, the one small specimen will produce enough offspring to populate your entire property after about three years.
I think of this daunting prospect as I take up my clippers, loppers and pruning saw to begin the annual task of pruning the roses of Sharon. Only two of the eleven specimens currently on my property were purchased by me. Two or three more were left by my predecessor. The rest were self-sown plants that proved useful and decorative on the south edge of a part of the front garden. This is another way of saying that I was inattentive one year and they grew to a size that made them difficult to remove. I made a virtue out of a necessity, pruned the interlopers into standard or tree form and let them grow. They have rewarded me by making extraordinary efforts every year to populate the entire surrounding area with more roses of Sharon.
Roses of Sharon are nothing new on the American scene. They were first documented by John Custis, a relative of Martha Washington’s first husband, in 1736, forty years before the Declaration of Independence. They have been fixtures in nursery catalogs since nursery catalogs began. Generations of gardeners have also passed along seeds, cuttings and young plants, as documented by southern garden historians Steve Bender and Felder Rushing in their hilarious and highly informative book, Passalong Plants.
My assortment of roses of Sharon is fairly typical. Some have single, hollyhock-like flowers in either white, pale pink or pale blue-purple, with red central “eyes.” The lower back garden is home to ‘White Chiffon,’ a deliberately purchased, double-flowered white variety. The upper back garden contains two double-flowered, blue-purple varieties, plus my pride and joy, ‘Sugar Tips,’ with double pink flowers and variegated foliage. Every single one of them is beautiful in bloom. The great virtue of rose of Sharon—in addition to its vigor—is that the bloom season is long. Each flower lasts only a day, but the flowers open continuously for up to six weeks. Pruning not only keeps the self-seeding under moderate control, but produces more floriferous shrubs.
If you have roses of Sharon, you should prune them right after they flower in the late summer or early fall, or at least before cold weather sets in. As I write this, the seed pods on the roses of Sharon in my yard are drying and ripening, preparing to split open and disgorge all of those seeds. Pruning in fall means that the vast majority of those seeds will never hit the ground and that is a very good thing. As I have gone about the business of garden clean-up, I have uprooted scores of rose of Sharon seedlings. The abundance persists, despite the fact that the resident deer posse seems to find the bushes tasty.
Some guidebooks advise pruning in spring. This is fine and will not harm nascent flower buds, but it does give the seed pods time to ripen and split. If time runs out in the fall, do it in spring, which is preferable to not pruning at all. Unpruned roses of Sharon quickly become leggy and ungainly, producing flowers only at the tops of the spindly branches.
Occasionally, when I have had all I can stand of plucking unwanted seedlings, I wish that I could replace all the roses of Sharon—except possibly ‘Sugar Tips’—with some of the sterile or semi-sterile varieties bred at and introduced by the U.S. National Arboretum. Hybridized by Donald Egolf, they are named after goddesses. ‘Diana’ features white flowers, ‘Aphrodite’ bears rose-pink blooms with red eyes and ‘Helene’ boasts white flowers and red eyes. ‘Minerva’ is similar to ‘Aphrodite,’ but the petals are more ruffled. It is worth seeking out these less-seedy varieties to ease your garden labors.
Even the goddesses need pruning, of course, but there is less urgency in the fall. Whenever you do the chore, lop off any dead or weak branches, and trim the rest back by about one third. Overgrown shrubs should receive a more severe haircut, with two thirds of the growth removed. When spring rolls around, don’t worry that you have killed your rose of Sharon. They are simply among the last shrubs in the garden to leaf out. Rest assured that neither you, nor Mr. Antlers, nor an invading army can stop them.
Local nurseries usually carry roses of Sharon in the spring. To obtain National Arboretum introductions and other varieties, try Greenwood Nursery, 636 Myers Cove Road, McMinnville, TN 37110, http://www.greenwoodnursery.com, (800) 426-0958.