May 2010 Plant of the Month: Ninebark
Posted: Thursday, May 6, 2010 8:01 pm
Submitted by Carol Reese
Reading through my already well-thumbed new edition of the Manual of Woody Landscape Plants, I was surprised to see a quote from Dr. Michael Dirr, esteemed woody plant guru, claiming that almost anything was better than a ninebark. He then went on to say that he’d written that decades ago, and that the newer cultivars had changed his mind.
True, the native form of ninebark, Physocarpus opulifolius, is a rangy plant with a brief bloom period, followed by a slightly longer show of colorful seeds. There wasn’t much to write home about, certainly. It was the introduction of forms with bronze to purple foliage that made the plant a vibrant player in the landscape for the length of the growing season.
Golden-foliaged forms have been in the trade for some time, and in cool climates, they are worthy garden additions. In hotter regions, however, the bright hues fade so fast you might feel the plants are wasting space.
The new dark-foliaged forms have much more to commend them. Of the several new dark-foliaged forms, if I were forced at gunpoint to pick only two, they would be ‘Summer Wine’ and ‘Coppertina’.
‘Summer Wine’ has a spreading, waterfall growth habit similar to an old fashioned spirea. The toothed, slightly lobed leaves flush in late spring, and though the purplish tint is apparent, it takes a few weeks of sunlight for the color to ripen and intensify. Flowering umbels of palest pink emerge from the leaf axils and generously stud each weeping branch. Perhaps even more showy are the umbels of red seed capsules that follow. Usually a new flush of growth covers these within a few weeks, so you are left with a graceful shrub of rich dark foliage. Many purple plants turn a muddy brown in the heat of the south, but the color of ‘Summer Wine’ just gets richer.
‘Coppertina’s growth habit differs slightly. It’s definitely a spreader, wider than tall, but the limbs don’t seem to have the same downward spill as ‘Midnight Wine. Newly emerging bronze foliage has limey gold tints in the center, but eventually the entire shrub is a rich dark copper. Flower and seed display is similar to ‘Summer Wine’.
If you find a form called ‘Diablo’, be warned that it is a much, much larger plant, and wishes to grow in a stiff, upright “V.” I didn’t care for it, until I came upon it at Chanticleer Gardens limbed up into a tree form, as you might a crapemyrtle. This revealed the a peeling white bark, which contrasted beautifully with the dark foliage and slightly pinker flowers. Lovely!
These plants are of easy culture. Though they are quite tolerant of shade, the best foliage color and bloom display will occur in sun. They accept a wide range of soil, except overly wet.
Carol Reese is the UT Extension Ornamental Horticulture Specialist for the Western District. She is located in Jackson, Tenn., and is a frequent and popular lecturer and writer. The UT Gardens in Jackson and Knoxville are both open to the public. See http://utgardens.tennessee.edu/ and http://westtennessee.tennessee.edu/ornamentals/ for more information.