All About Phlox

It’s always easiest to write about a group of plants when the common name and scientific name are the same, especially when it’s easy to remember, like “phlox.”   Phlox is a genus of plants, virtually all of which are North American in origin.  Apparently there is one species that lives in Siberia, perhaps sent there many years ago for misbehavior.  Some are annuals, but most are perennials, and terrific garden plants, at that.

It’s hard to generalize because in nature they are found in very diverse environments, from sandy slopes to prairies to moist woodlands.  Some are even native to Maryland.  Because they have showy flowers and have such a wide range of habitat choices, you are bound to have one or more spots in your garden that would be just perfect for phlox.  They come in all flower colors, and the flower shape makes them attractive to hummingbirds and the also quite cool hummingbird moths.

Going from short to tall, here are our favorites:

Creeping Phlox, Phlox subulata: hugs the ground, spreading and cascading over walls, this phlox needs good drainage and does best on a slope.  Colors include blue, red, pink, purple and some bicolors.  It is completely covered with blooms for two or three weeks, and then you are stuck with the foliage, which is pretty nice on some varieties (McDaniel’s Cushion, Emerald Cushion Blue, Emerald Cushion Pink) and not so great on others; some are evergreen.

Woodland Creeping Phlox, Phlox stolonifera: This shade tolerant ground cover phlox spreads by aboveground stems called stolons, and once it’s established, it’s easy to propagate by just digging chunks of it out of the soil.  It comes in a lavender-blue (Sherwood Purple, which I have found to be the most vigorous), blue, pink and white.  It does best in soil that gets some water during dry periods, and prefers some morning sun.  It’s also evergreen.

Woodland Phlox, Phlox divaricata: I’ve seen this growing wild at Great Falls National Park, in lower areas near the river.  In bloom it’s about a foot tall, and like the other creepers, is spring-blooming.  This seems to like a soil with a good organic content and doesn’t like to dry out for long periods.  A little fussier than Phlox stolonifera, in blue and white.

The hybrid Paparazzi series (with names like Gaga and Paris, named after various celebs) is a low grower that offers a very long blooming period, even throwing off some blooms in the summer.  We have a couple of three year old Gagas in our pollinator garden, and they have already been blooming for over a month (it currently being mid April).

Another hybrid, this one discovered in the wild is Phlox ‘Minnie Pearl’, which gets about 18 inches tall.  The foliage comes up quite early, and the pure while flowers appear in late April/early May.  It spreads by underground stems (rhizomes) and makes a nice clump.  This variety is very resistant to powdery mildew which is a concern on the taller phlox in particular.

Tall Garden Phlox, Summer Phlox; Phlox paniculata:  a traditional perennial for the summer garden, this waist-high phlox has the widest color range, with the widest selection in white, pink and red but also orange and purple.  The wild form is magenta, and varieties that are closest in color to this tend to be the most powdery-mildew resistant.  We are always looking for varieties that are resistant to this disease, which grows on the foliage, turning it gray before it gets depressed and falls off the plant, leaving a lot of bare stems.  Our care signs will tell you which are the most disease resistant.  That said, you can reduce the visual impact by planting phlox as a taller background plant and planting something in front of it to hide its “ugly legs.”  This phlox is best in full sun and needs supplemental fertilizer.  Good air circulation will reduce disease issues, as will pinching off some of the spring growth at ground level, to leave 5-ish stems to develop.  This allows for better air circulation and stronger stems.

We offer other phlox as they are available, so we always have some from which to choose.

by Larry Hurley, Behnke horticulturist