Many people have strong feelings about phlox. Some love its beautiful blossoms and others are frustrated by the deer browsing and its spreading nature. Regardless of which side you lean towards, there are good reasons why it’s a popular garden plant, and since some species are native to the North Country, let’s take a closer look at a few of those!
First though, a bit about the genus: Phlox is a group of perennial flowering plants, most of which are native to North America. They are frequently cultivated by humans for their showy and often fragrant flowers, and with many different species to choose from and countless varieties and cultivars, it can be extremely versatile in a garden. In fact, the genus name Phlox comes from a Greek word meaning flame, in reference to the vibrant flowers of some varieties. Phlox flowers are a tubular shape which divides into five petals – although you may occasionally find a four- or six-petaled blossom in a cluster. The flowers often have a color difference in the center around the opening, which serves as a guide for pollinators seeking nectar.
Let’s start with a true-blue wild native – Phlox divaricata, which goes by common names including timber or wood phlox, wild sweet william (not to be confused with Dianthus barbatus, which is also called sweet william), and wild blue phlox. Its native range covers the central and eastern United States and eastern Canada, growing wild in forest floor environments, where it may grow in clumps or spread more horizontally, reaching 6 to 12 inches high. In gardens it prefers partial to full shade, and moist well-drained soil that is high in organic material, to approximate its natural growing conditions. P. divaricata blooms in the spring, starting as early as April. The wild type is typically a light blueish purple color and has narrower, more separated petals than most phloxes, but cultivated varieties and cultivars can range from bright violet pink to blue and sometimes white, and flower shape may be similar to other domestic species.
Next, Phlox subulata, which is known commonly as moss phlox, creeping phlox, thrift, and more rarely, moss or ground pink. Interestingly, “pink” is a name which this phlox shares with some members of the Dianthus genus, from which we get the word for the color pink. P. subulata is also native to central and eastern Canada and the U.S., and is most prevalent in the Appalachian Mountains. It has a very different growth habit than some of the other species, with trailing stems spreading from a single base to form a dense mat of foliage – about six inches high and two to three feet wide. Stems become woody with age, and foliage becomes sparser in the center of the plant as new growth continues around its outer edges. If you want to maintain density at the center, the stems can be cut back to about half their length when the plant is done flowering. P. subulata can be grown in sandy or gravelly soil, as it often does in the wild, and it is more tolerant of hot or dry conditions than most other species of phlox. It grows in a variety of colors, is spring flowering like P. divaricata, and has a bit smaller flowers than the other two species (about ¾ inch wide).
The last species we’ll look at is garden phlox – Phlox paniculata. Some other common names for it include autumn or fall phlox, summer phlox, and tall phlox, and you can likely guess a few of its features from that list of names. It does indeed bloom from midsummer into fall, and grows taller than most other species, about two to four feet. Here in the pollinator garden at the Extension Learning Farm, our P. paniculata has just started blooming, and past years’ records show it will be mostly done by mid-August, but may trickle into late September.
While this species is native to central and eastern North America, most current wild populations are thought to be escaped from cultivated plants, and much of the original native populations may be lost. Perhaps due to this, it’s somewhat unclear whether the P. paniculata in our area is actually native or naturalized. Either way, it serves as a very valuable food source for pollinators – its dense clusters of blossoms mean butterflies and other nectar-feeding animals love it, as they get a lot of nectar from a single plant. Wild types, which you may have seen growing in roadside meadows and similar environments in our area, are typically moderate shades of pink, purple, or rarely, white. Cultivated varieties, however, can be almost any color, from deep purple or blue, to shocking hot pink or red, and even orange, yellow, or variegated.
No butterflies or moths in our area use phlox species as their sole host, but it is important to a few. The majority of those are fairly generalist, but Phlox is one of only two plant genera that can host the larvae of Olive Arches (Lacinipolia olivacea); it’s one of four options for Darker Spotted Straw Moth (Heliothis phloxiphaga)
Many butterflies are attracted to phlox for its nectar – a notable frequent visitor is the Eastern Tiger Swallowtail (Papilio glaucus). It’s also a favorite of hummingbirds, which like plants with bright, tube-shaped flowers.
Some other truly fascinating creatures that enjoy these flowers are the hummingbird moths – a few species of moths whose shape, behavior, and sometimes even coloration strongly resemble that of a hummingbird. Notable species in North America include the Hummingbird Clearwing (Hemaris thysbe) and Snowberry Clearwing (Hemaris diffinis). Beebalm, or Monarda species, (featured as a previous Native Plant of the Week!) are another favorite food of these adult moths. While the adult hummingbird moths can feed from a variety of flowers, their larvae typically require a specific host plant, such as honeysuckles, dogbane, or members of the rose family. The larvae pupate over winter in leaf litter below their host plant, so if you have the plants that support this beautiful pollinator, consider allowing the dropped leaves to stay and shelter them.
Phlox can be cultivated from seed, root divisions or stem cuttings. It is considered juglone tolerant (can be successful near walnut family trees), but can be vulnerable to some other issues, such as powdery mildew. These plants are very palatable to some herbivores such as deer and rabbits, so you may have issues with those animals if their populations near you are large and your garden is not protected.
Different species of phlox have a wide variety of preferred growing conditions, as we briefly covered for each species we have looked at. Most or all of them will self-seed and spread in favorable conditions, sometimes aggressively. If you have planted a cultivar, it’s important to note that its seeds will not necessarily produce a plant like the parent – they will likely revert to more generic characteristics. If this is something you want to avoid, you will need to remove the seed heads before the seeds drop. However, as the seeds are also a good food for seed-eating birds, it might be better to leave them, or start out with a more natural variety of phlox that will breed true.
Phloxes are a beautiful and incredibly versatile group of plants; there’s a species that can thrive in just about any setting you’d like to foster, from alpine rock gardens to damp open meadows, and that can be used as anything from groundcover to cut flowers. If all this strikes your fancy, then plant some phlox and enjoy!
Resources:
- Phlox | North Carolina Extension Gardener Plant Toolbox
- Phlox divaricata (Blue Phlox, Wood Phlox, etc.) | North Carolina Extension Gardener Plant Toolbox
- Phlox subulata (Creeping Phlox, etc.) | North Carolina Extension Gardener Plant Toolbox
- Phlox paniculata (Autumn Phlox, Garden Phlox, etc.) | North Carolina Extension Gardener Plant Toolbox
Native Range Info:
- Search Results – NYFA: New York Flora Atlas
- USDA Plants Database Plant Profile General (P. divaricata)
- USDA Plants Database Plant Profile General (P. subulata)
- USDA Plants Database Plant Profile General (P. paniculata)
Pollinator Info:
Amalia Kanitz grew up on a small farm in De Kalb NY and is currently a rising sophomore at St. Lawrence University. She was involved in 4-H for many years, and participated in horticultural knowledge competitions up to the national level. This summer, she is the SLU Public Interest Corps Garden-to-Table intern at CCE, helping with the Master Gardener Volunteer and Master Food Preserver programs. Amalia enjoys making visual art and music, learning about native plants and foraging, and appreciating the little things in nature.