Plant Data Sheet

Species (common name, Latin name)

Spreading Phlox, Phlox diffusa


It is widespread through the Cascades from southern British Columbia to the Sierra Nevada of California. Eastward, it ranges across northern Washington, Idaho, and Montana to the west slopes of the Rocky Mts.


Climate, elevation

Spreading Phlox is a wildflower of middle to high elevations in the mountains. It is typically found in open forests or open rocky slopes.

Local occurrence (where, how common)

Spreading Phlox is found from the mountains of Vancouver Island, south through the Olympic Mts, and at Saddle Mt in the coast range of Oregon. It may occasionally be found as far south as the mountains of central Idaho and northeastern Oregon.

Habitat preferences

Exposed rocky sites to open forests from middle to high elevations (WNPS)

Plant strategy type/successional stage (stress-tolerator, competitor, weedy/colonizer, seral, late successional)

Creeping perennial

Associated species


May be collected as: (seed, layered, divisions, etc.)

Cuttings, seed, divisions

Collection restrictions or guidelines


Seed germination (needs dormancy breaking?)

Seeds should be chilled in the refrigerator a week before planting. They may be started indoors at a 65-degree temperature, 8 to 10 weeks before it's safe to plant outside.

Seed life (can be stored, short shelf-life, long shelf-life)


Recommended seed storage conditions


Propagation recommendations (plant seeds, vegetative parts, cuttings, etc.)

Seed when ripe or in early spring cuttings in late summer (The rock garden database). They should be sown in two parts of loam and one part of leaf mold or peat moss, with a liberal amount of sand added. Lightly cover them. Set a pane of glass over them. Gradually harden them off before setting outdoors. When they are to grow in a sunny greenhouse, seeds may be sown in pots of sandy soil from August to February to provide blooms in the late winter and early spring. The perennial, summer flowering Phloxes can be increased readily by cuttings, which may be taken at any time during the spring and summer.

Soil or medium requirements (inoculum necessary?)

Prefer sand

Installation form (form, potential for successful outcomes, cost)

Fresh shoots of the current year's growth are used; those that are flowerless are the best choice, though even the tops of shoots that have flowered may be used if necessary. Insert these into a bed of sand in a frame and keep it closed and shaded for a few weeks.

Can also be propagated by root cuttings taken in early autumn. The easiest way to increase perennial Phloxes is by separating large clumps into several rooted pieces in October or early spring and replanting immediately. Only the outer pieces should be used to replant because these are the younger portions. However, the best method is to raise new plants from cuttings. The perennial, spring flowering Phloxes may be increased by seeds sown in the spring, by soft cuttings of non-flowering shoots taken in early summer and inserted in a bed of sand in a cold frame, or by root division in the spring or early summer (The rock garden database)

Recommended planting density


Care requirements after installed (water weekly, water once etc.)

sunny, dry, rock crevices, protection against winter wet
alpine house, poor, drained soil, sun.
(Botany .com)

Normal rate of growth or spread; lifespan

not exceeding 10 cm in height

Sources cited (Washington Native Plant Society) (The rock garden database) (Botany .com)


Data compiled by (student name and date)

Roger Whalley 04-29-03