Also known as blue phlox or meadow phlox, wild sweet William (Phlox divaricata) is a perennial wildflower that displays clusters of lightly fragrant springtime blooms of white or pale blue atop fuzzy green stems. The plant reaches a height of 1 foot at maturity, with a spread of about 2 feet. Native to the Eastern United States, wild sweet William is suitable for planting in U.S. Department of Agriculture hardiness zones 4 through 8. Unlike most types of garden phlox, wild sweet William prefers full or partial shade.
Provide wild sweet William with about 1 inch of water every week during warm, dry weather. Don't allow the soil to become soggy and don't irrigate if it is still moist from the previous irrigation, because a moist environment harbors diseases such as mold, mildew and rot. Keep the foliage as dry as possible by watering with a garden hose at the base of the plant.
Fertilize wild sweet William once in spring if growth appears stunted or the foliage is pale or yellowish-green. Use a rose fertilizer applied at the rate recommended on the container.
Pinch flowers from the plant as soon as they wilt. Deadheading causes the plant to produce more blooms instead of going to seed.
Pull extra sweet William plants if necessary. The plant reseeds itself generously every year and may become crowded. Thinning creates an attractive appearance and promotes air circulation, preventing moisture-related diseases.
Shear the plant down to 3 to 4 inches after flowering ends in early summer. A yearly pruning keeps the plant neat and healthy.
Divide wild sweet William in autumn if the plant appears crowded, or if the center dies down and looks messy. Dig up the entire plant, digging wide and deep to avoid damaging the roots. Carefully pull the plant into sections, ensuring that each section has at least four or five health roots. Plant the divided sections in full or partial shade and any type of well-draining soil.
Things You Will Need
- Garden hose
- Rose fertilizer
- Garden shears or pruners
- Wild sweet William works well in a butterfly garden, where the blooms attract western pygmy blues, swallowtails, gray hairstreaks and other butterflies.
- Missouri Department of Conservation: Blue Phlox (Wild Sweet William)
- Lady Bird Johnson Wildflower Center: Phlox Divaricata L.
- The New Sunset Western Garden Book; Kathleen Norris Brenzel, Editor
- The Gardener's A-Z Guide to Growing Flowers From Seed to Bloom; Eileen Powell