Downy phlox (Phlox pilosa) is an inhabitant of jack pine barrens such as those in Washburn County, Wisconsin where it occurs with other drought tolerant species on sandy soils with only a thin layer of organic matter. It is short plant (to 0.5 meter) with long-linear, fuzzy (“pilose”) leaves arranged in opposite pairs along the stem. The pale lavender to pink fragrant flowers are borne at the top of the stems and appear from May to early June.
Downy phlox is easily grown in gardens with rapidly draining coarse or sandy soil in full sun. New plants can be started from seed planted in the fall where the plants are to be grown. Stolons (the leaves are rounded on these) that have rooted can be carefully cut from the parent plant and replanted. Growth is slow whether propagation is by seed or divisions made from rooted stolons. Too much shade or competition from faster growing plants is not tolerated by downy phlox. Downy phlox does best along the outer edges of the flower garden or in prairie plant gardens with short grasses and forbs. In prairie gardens it is a good idea to burn the grasses every few years in the spring. Burning will create open spaces where downy phlox and other shade intolerant forbs may grow.
Phlox flowers are attractive nectar sources for hummingbirds, many species of butterflies, and white-lined sphinx and clearwing moths (Sphingidae). Besides being a nectar source downy phlox is also the exclusive larval host plant for the phlox moth (Schinia indiana) which is scarce throughout its range owing to the near destruction of native prairies. The larva of phlox moth bore into the flowers and eat them but later eat the developing fruit from the outside. Their development is slow and takes almost a full year from egg to adult moth.
I have planted a few purchased downy phlox in one of my flower gardens. Their increase has been slow and although sphingid moths visit the flowers I have not yet seen any phlox moths. This is hardly surprising given that I live far from any large populations of downy phlox and jack pine barrens habitat. But maybe some day they will arrive.