At high summer, no respectable flower garden should be without garden phlox or Phlox paniculata. Strange to say, the suburb where I live is somewhat short on phlox. This is probably because it is long on easy to grow annuals like impatiens. There is nothing wrong with impatiens, but a well-established clump of brilliantly colored phlox is a dramatic and heartening site. Out in the country, near my family’s summer cottage in Central New York State, gardens worth their salt always feature two plants—a lilac by the back door for spring and a big patch of phlox for mid to late summer.
Why have these two garden stalwarts persisted? Alluring beauty and fragrance are great attributes, but perhaps equally important, they are tough, easy to grow, and quite easy to propagate. In the case of garden phlox, you can make more every year or two by splitting an established clump, either as it emerges in spring, or after it blooms in early fall.
Propagation began early on. The ancestors of today’s plants were native to North American and occurred naturally from New York State south to Georgia and as far west and south as Illinois and Arkansas. American settlers no doubt encountered wild Phlox paniculata shortly after arriving on this continent. By the early eighteenth century, it had traveled to England and in 1730; it was reportedly blooming there in the garden of Dr. James Sherrard, apothecary and plant collector. The first written description of Phlox paniculata was made by Philadelphia nurseryman and plant collector John Bartram in 1737. The species still blooms today in Bartram’s restored garden. By the mid to late nineteenth century, there were over 800 named selections of phlox on the market. When I think about that, I am astounded by the plethora of available choices, but also wonder if some of those 800 varieties looked so similar that they were indistinguishable from each other.
Out in the country, eighteenth, nineteenth and twentieth century farm wives probably did not have the opportunity to pick from a plethora of varieties, but relied on divisions provided by relatives or friends. This is why many old gardens in the same area also have the same phlox varieties.
Phlox paniculata, acquired its Latin species name from its large, showy flower panicles or terminal flower clusters. Each of those panicles is composed of scores of five-petaled, tubular flowers. Unlike many other native plants, Phlox paniculata has not attracted a host of colorful nicknames and remains known to the world as plain “garden phlox.”
The name is plain, but the plant is elegant, growing two to four feet tall, with elongated, alternate leaves and glowing flowers in shades ranging from white to deep rose, red, blue-purple and purple. Bi-colors, especially those with a bright central “eye”, are longtime favorites. Plant breeders have even created orange cultivars, though they never look like real phlox to me. In the past I have felt drawn to old-fashioned varieties, like the ever-popular, white flowered ‘David’. Two worthy varieties that have stolen hearts for years are bright pink ‘Dodo Hanbury Forbes’, from the nineteen fifties; and violet-blue ‘Katherine’, bred in the roaring twenties and featuring a white “eye”. All three are still available commercially.
The range of choice is still large and includes dwarf varieties like ‘Swizzle’, with pale pink flowers accented with brighter pink “eyes”. It grows only 16 inches tall—as opposed to up to three feet for normal phlox. Another flashy short variety is ‘Red’ from the Flame series of garden phlox. Both are suitable for containers as well as beds. ‘Blue Paradise’, a tall phlox, is as close to true blue as you are going to get in the paniculata species.
The words “powdery mildew” strike fear in the hearts of many phlox lovers, as phlox is very susceptible to the fungus disease that turns the foliage powdery white. Powdery mildew thrives in the hot sticky conditions under which many of us spend our summers. The best way to fight it is to water early in the day so that plants have a chance to dry off before nightfall. Good air circulation among plants also helps. However, the best thing you can do is buy varieties that have at least some resistant to the disfiguring ailment.
Breeders have also addressed the powdery mildew problem, making a point of selecting plants and introducing phlox that are resistant to the disease. ‘David’, for example, is purported to be mildew resistant. It is so lovely and hardy that the Perennial Plant Association, a trade group, named ‘David’ the PPA “Plant of the Year” in 2002. Newer varieties are almost all touted as mildew resistant, but some are more reliable in that department than others.
Phlox probably work best in a loose, old-fashioned cottage garden, fitting right in with the asters that are just starting to bloom as the phlox conclude their run. Tall asters are about the same height as tall phlox and the white-pink-blue-purple color scheme matches as well. Combining phlox and asters in one bed is a good way to ensure an ongoing supply of late summer color. The plants also work well in the company of butterfly bushes and white or blue veronica, doing their bit to attract all kinds of pollinators.
All varieties are sun lovers and while phlox grows in just about any soil, it does better in rich, well-amended earth. To prolong its season of bloom, deadhead the top flower panicles promptly when the petals fall. This encourages side shoots to produce more flowers.You may be able to find potted Phlox paniculata in your favorite garden center, if that retailer restocks perennials for fall planting. If not, try Bluestone Perennials. Find them at 7211 Middle Ridge Road, Madison, OH 44057, (800) 852-5243, www.bluestoneperennials.com. Free catalog.