Woodland Phlox (Phlox divaricate): A Big Punch in a Little Packet
Jim Lakin MD, Master Gardener
It’s that beautiful carpet of pastels appearing in moist woodlands across the Midwest in the spring – Woodland Phlox. Otherwise known as “Sweet William,” this native plant has many reasons to be at home in your garden. Read more about the virtues of Woodland Phlox and then decide if you will grow it from seed or as an established plant. Not only will you enjoy this plant but pollinators love it as well.
The Phlox family (Polimoniaceae), tend to be a diminutive bunch, with delicate spring blooms. Their delicacy is both charming and deceptive as they are a persistent bunch that will form a lovely groundcover if left to their own devices. This is certainly true of woodland phlox which is found across the entire Midwest although more prevalent in the northwest, inclusive of the deciduous forests of Minnesota. There it can carpet the ground, blooming from mid to late spring. You will find it most profusely in a mesic forest, that is, one in which an ample supply of moisture is found throughout the growing season. It will however grow in most woodlands as long as there is moisture during its blooming season in spring. Ironically, woodland phlox is very summer drought resistant. Thus, it is hardy across the Midwest from Zones 3 through 8.
Woodland phlox readily grows from seed and will self-sow quite vigorously. This is an important characteristic, as the individual plant is fairly short-lived for a perennial at 3 to 5 years. As you might imagine, it is a shade-loving plant but will tolerate part sun. As it blooms in the spring, the light blue flowers exude its delicate perfume earning its other name of ‘Sweet William.’
Woodland phlox combines quite well with a variety of other woodland, shade-loving plants. It fits in nicely with other later-blooming groundcovers or larger shade perennials. The springtime stalks rarely exceed 18 inches and quickly disintegrate after blooming. Since the foliage often disappears after blooming, it does not make a good stand-alone ground cover and should be integrated with other species.
Unfortunately, the bunnies love woodland phlox so it’s best to protect new plantings until a bigger colony is established. As is the case with so many native perennials, woodland phlox is pollinator friendly and attracts bumblebees, sphinx moths, butterflies and hummingbirds. If you are thinking about installing a pollinator lawn, woodland phlox can be integrated into the shady parts quite easily.
Woodland phlox blooms range in color from white to soft blue. Occasionally you will find some rosy to purplish flowers. Since these folks do self-seed, the color of various strains will modulate from generation to generation. Yet the perfume of springtime ‘Sweet William’ is ethereal no matter the hue.
Photo Credit: University of Wisconsin Extension (1,2)