COMMON NAME: phlox
SPECIES, HYBRIDS, CULTIVARS:
P. paniculata-includes varieties in many colors ranging from white to pink, purple, and red. P.p. ‘White Admiral’-white. P.p. ‘Bright Eyes’-light pink with dark pink centers. P.p. ‘Vintage Wine’-claret red; blooms late in summer. P.carolina-only in white and pink; no problem with reversion. P.c. ‘Miss Lindgard’-mildew resistant; blooms June and July. P. divaricata-blue phlox; blooms April and May in a shady area; grows only 18 to 24 inches tall. Each of these is perennials. P. drummondii-annual phlox; red or pink.
TYPE: annual and perennial
DESCRIPTION: Beautiful and sweet smelling, phloxes provide an important part of the summer garden. Colors include white, red, pink, salmon, lavender blue, orange, and deep purple. The flower heads are attractive mounds of five-petaled florets. The plants begin to bloom around the first of July and continue to do so for many weeks.
CULTIVATION: The greatest problem in growing phloxes is the prevalence of mildew on the plants. Be extremely careful to avoid getting moisture on the leaves, and don’t grow phlox plants near brick or stone walls that retain moisture. Many strains have been developed that are mildew resistant, and these are highly recommended. Phloxes do like moist roots, however. Water with a soaker hose instead of a general lawn sprinkler to keep the roots moist without getting the leaves and flowers wet.
Phlox blossoms were used extensively in Victorian England for sending messages through tussie mussies and bouquets. Not only is their scent delightful, but their message is welcome, for phloxes mean a proposal of love and a wish for sweet dreams.
The word phlox is a Greek word meaning “flame” and was given to this plant because many of the blossoms were red.
Phloxes have been among the most popular of all garden plants brought to Europe from North America. It was not cultivated in American gardens until it was reintroduced here from European horticulturists.
The leaves of phlox were sometimes crushed and added to water to cure such ailments as skin disorders, abdominal pain, and problems with eyes. The leaves were also used as a gentle laxative.
Phloxes are particularly cherished for their sweet scent. White and pale varieties are additionally appreciated for their luminosity and scent in the garden in the early evening.
Historically, Phlox paniculata was perhaps the most prominent plant in perennial gardens from the turn of the century through the 1940s. As some have put it, “Phlox Ruled”! Although native to North America, it was the Europeans who first recognized the potential in our simple magenta or white wild phloxes, and who experimented with selecting and breeding, then re-importing the improved types back to the U.S. Two very notable names associated with the development of phlox are Karl Forster and B.H.B. Symons-Jeune. The American breeders made serious contributions as well, and references have been found for over 800 named varieties! That may sound like a lot, but there are now over 4,000 named varieties of Hosta, and an astounding 68,000 Daylilies out there. (Speaking of those 800 phlox – it’s unbelievable that they were all unique. Like those thousands of daylilies, there are only so many distinctive combinations possible, and many unremarkable or duplicate varieties were probably hustled into the market. Just like nowadays, people lose plant tags and wind up renaming plants. It remains a problem.) The apogee of phlox planting came in the early 20th century, but in the 1940s there were still over 220 named varieties available in New England nurseries. Most of these have sadly gone missing. Phlox suffered a downturn in popularity from the 1940s to the 1980s, when perennial gardening, in general, came to be regarded as old-fashioned and rather quaint, and this is when so many old cultivars were lost. In recent years, however, there has been growing interest, and many new cultivars are being developed, with a recent focus on producing dwarf plants, and increasing mildew resistance.
Phlox prosper in a cool sunny climate, well-watered, in the rich sweet soil. In much of the country, they will thrive in full sun, although partial shade is fine, as long as the plants receive at least 6 hours of direct sun. In the southern or hot climes, partial shade is recommended. The soil should be rich and slightly sweet (alkaline), so if your soil tends towards the acidic side, regular applications of lime are recommended, say every two or three years. The plants should be set in quite rich soil, enriched with compost or aged manure. This type of soil will also hold water well, an important feature, for phlox do not do well in hot dry soils. Mulching will assist in water conservation and in keeping the soil cool. Because they are heavy feeders, the even beautifully prepared soil will decline after four or five years, and it is best to plan on resetting your plants on a regular basis, every four or five years. The plants should be lifted out (in fall or early spring), divided into several chunks, replanting only one of those chunks in the old spot. What to do with the remainder? Either expand the phlox border or give them to a neighbor.
Phlox are very easy to increase by simple division, in late summer or early spring. Commercial growers tend to propagate them using root cuttings taken in late summer. Stem cuttings can be taken in early midsummer, but only do well if kept in very humid conditions, such as in a mist bench, or at least enclosed in a plastic bag. The success of the bag method depends on close attention to cleanliness in avoiding fungal rots and ensuring the light conditions are neither too dark nor too sunny.
While phlox start easily from seed and often self-sow into the garden, it is rare for the seedlings to have the same coloring and habit as their parent. In fact, it is good policy to deadhead your phlox before they go to seed, as those little self-sown seedlings tend to grow up into vigorous plants of a decided magenta hue and can, in a few years, crowd out the mother plant. In our fields, we will go through every year looking to uproot these rogues, and we find new ones every year. (Of course, once in a while these seedlings create exciting new plants, so we like to pay attention before we pull, and so should you!)
Many people find their plants are troubled with powdery mildew, a white fungus that bespeckles or coats the leaves, typically in high summer. Although it is never fatal, it can be unsightly, and may lessen flowering and lead to leaf drop. I first want to remind us how lucky we are that this is the biggest problem with phlox, compared to so many serious problems another plant may have, all those beetles, thrips, soots, aphids, weevils and so forth. Mildew tends to be a greater problem in regions with high humidity, but will also affect phlox that are planted in dry soils. I consider that it is pretty much endemic, and if your phlox are prone to it, it will turn up in every garden sooner or later.