Jennifer Schultz Nelson
Extension Educator, Horticulture
Usually you'll hear me say that common names can make figuring out the true identity of a plant a real challenge. But phlox is a different story. Phlox is technically the genus to which the plant belongs to, but there are at least 67 species in this genus. So to say you're growing phlox is only the beginning of describing your plant.
If you get to know some of the phlox species and cultivars available, it is very possible to have blooms through most of the spring and summer. Phlox is native to North America, and very well adapted to the climate here, making it a great choice for gardens in central Illinois. The name phlox comes from the Greek word for flame, which is in reference to the spectacular colors of phlox blooms. Colors range from white, to reds, blues, pinks and purples.
Each spring, creeping phlox (Phlox subulata), also known as moss phlox or moss pink, is literally covered with blooms over every possible inch of their low-growing form. At a time of year when we all crave color after a dreary winter, it is no surprise that many garden centers sell tons of creeping phlox in full bloom to eager homeowners.
Creeping phlox is a natural fit for a border or rock garden in a sunny, well drained location. It is particularly striking when allowed to cascade over the edge of a wall. It can also help control erosion on slopes. Growth is low, at a maximum of about six inches tall, and matted, with needle like leaves. Seeing the plant, one realizes why one of the common names is moss phlox. Additionally, colors are vibrant and varied, not just pink like one common name might suggest.
Just to add to the confusion, Phlox stolonifera is also called creeping phlox, and some argue it is the "true" creeping phlox. This creeping phlox grows slightly taller, at one foot tall. Its cultural requirements are slightly different, preferring partial shade to sun. Color is not sacrificed though, as the same spectacular range of vivid colors can be found in Phlox stolonifera as well. As the latin name suggests, this creeping phlox spreads via stolons, or specialized above ground stems capable of producing roots at the leaf nodes.
Many people know phlox as summer phlox, Phlox paniculata. This phlox is more forgiving on light levels, growing anywhere from partial shade to full sun. Of course, it still prefers well-drained soils, as do most plants, not just phlox. The same spectrum of colors is found in summer phlox, making them highly desirable additions to summer flower beds. They are substantially larger than the creeping phlox, at anywhere from two to four feet depending on the cultivar.
Phlox was a favorite flower of the Victorian Era. Bright and showy, it made a statement in elaborate gardens of the time. It also held the romantic meaning of "our souls are united", an emotional statement most prim and proper people of the time probably would never utter aloud.
One drawback to phlox in general is its tendency to acquire powdery mildew at some point during the growing season. This fungal disease covers the stems leaves in a white powdery film. This white powder is actually the fungus itself. While only very severe cases will affect flowering, overall the disease detracts from the beauty of the plant.
Culturally, spacing plants properly and watering in the morning so plants can dry out rather than remaining wet for hours reduces powdery mildew to some extent. In addition to these cultural strategies, gardeners should consider buying genetically mildew resistant plants if possible. This will increase chances of maintaining beautiful phlox well into the growing season.