When you're planning or renewing a bed of ornamentals, take a good look at phlox, an American native, that is treasured in many forms in public gardens around the world.
There are 61 species in this genus, according to a book by James H. Locklear, entitled simply "Phlox." Fifteen species grow naturally in Idaho. All except the P. sibirica are native to America, that exception from Siberia. There is even a Phlox idahonis, that grows in meadows near the tiny town of Headquarters, Idaho, 13 miles north of Pierce.
The only kind of phlox I've grown was P. paniculata "David," but that's an oversight we need to correct. Treat phlox right and different varieties will supply flowers from April to September. All varieties need good air circulation, moist soil and appropriate sun exposure.
Woodland phlox (P. divaricata) and creeping phlox (P. stolonifera) thrive in part to full shade, but garden phlox (P. paniculata), early phlox (P. maculata) and moss phlox (P. subulata) prefer full sun.
Some varieties are susceptible to powdery mildew that make the foliage look ratty, but that seldom happens in our dry climate as long as you give your plants adequate space and air circulation. Breeders have been focusing on building the plant's resistant to powdery mildew, but you can help by judicious siting.
Plant so that they'll get good air circulation, and when one of the perennials begins to poke up from the earth, cut starts back to just three or four spaced shoots. Also, divide perennial phlox every two or three years.
Creeping phlox blooms in April and May, and should be trimmed in spring, if at all. It spreads by stolons, or runners, so if you want to contain it, cut those off. If you want to divide it, do so after it blooms.
Woodland phlox bursts into blossom in May and June, and you can prolong flowering by deadheading with hedge trimmers. Seed heads turn tatty brown if left on the plant.
June and July are the bloom months for "early" phlox, and flowering can be greatly extended by deadheading. Deadhead the main truss to just above lateral buds.
Don't worry about seeds setting on this phlox, since it's self-sterile. It thrives in moist, fertile soil, rich in organic matter. For best performance early phlox should be divided every two years.
Since home landscaping preference has gone to flowering islands in the suburbs, there's no longer emphasis on "back of the border" plantings in which P. paniculata or garden phlox shines. It blooms from July to September, with proper deadheading.
Deadheading prevents self-seeding, and in this instance, that's desirable.
Seeds of P. paniculata don't come true to parents, and their presence cuts down on the air circulation necessary to prevent powdery mildew. If plants do get badly infected with powdery mildew, cut them to the ground and let a few spaced specimens re-grow.
Heady aromas of phlox are an added inducement to grow this remarkable American plant.
Send garden questions to firstname.lastname@example.org or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.