Selecting perennials for the home garden can be a bit intimidating. There are literally thousands of species and varieties available. Among those that deserve consideration are several species of Phlox. (The word phlox is Greek meaning flame and refers to their brightly colored flowers.)
One of the most widely grown Phlox species is garden phlox (Phlox paniculata). Garden phlox is a clump-forming, upright plant which produces large, showy flower clusters in summer. Plants are generally 2 to 4 feet tall. While the species itself is seldom grown in gardens, there are numerous varieties available. Gardeners can choose from white, pink, red, blue, and purple flowering varieties. Unfortunately, most varieties of garden phlox are susceptible to powdery mildew. Powdery mildew produces a grayish white coating on the stems and leaves of infected plants. Infected leaves turn yellow and eventually dry up and turn brown. Mildew infected plants become ugly eyesores in perennial gardens. As a result, the popularity of garden phlox has declined in recent years. While good cultural practices, such as adequate plant spacing, can reduce the severity of powdery mildew, gardeners wishing to plant garden phlox should select mildew resistant varieties. Mildew resistant varieties include 'David' (white flowers) and 'Eva Cullum' (flowers are pink with red eyes). Garden phlox grows best in moist, fertile, well-drained soils in partial to full sun. Plants often need to be watered during hot, dry periods.
Spotted phlox (Phlox maculata) is similar to garden phlox in appearance and cultural requirements. However, there are several differences. Spotted phlox is earlier flowering, has darker green leaves, conical flower heads, and better mildew resistance. Plants are generally 2 to 3 feet tall. Spotted phlox is native to Iowa. It is most commonly seen along roadsides and prairie swales in northeast Iowa. The species has mauve-pink flowers. Excellent cultivated varieties include 'Alpha' (rose-pink flowers with darker eyes), 'Omega' (white with pink eyes), 'Miss Lingard' (white), and 'Rosalinde' (purple-pink).
Another native Phlox species is woodland phlox (Phlox divaricata). It is commonly found in moist, partially shaded woodland sites. Woodland phlox produces loose clusters of showy blue to violet flowers in spring (April to June). Plants are typically 12 to 15 inches tall. Woodland phlox is an excellent plant for woodland gardens. It can also be used in the front of the perennial bed or planted in clumps amongst other low-growing, shade tolerant perennials. 'Fuller's White' is an excellent variety. It is slightly smaller (8 to 12 inches) and is covered with white flowers in spring. 'Chattahoochee' (a cross between P. divaricata var. laphamii and P. pilosa) has lavender-blue flowers with dark purple centers.
A common sight in many home landscapes in spring is the brightly colored flowers of moss pink or moss phlox (Phlox subulata), commonly called "creeping phlox." Moss phlox forms dense, carpet-like mats. Plants are 4 to 6 inches tall. Its foliage is narrow, stiff, and needle-like in appearance. Flower colors include white, pink, red, blue, and purple. Excellent varieties include 'Emerald Blue,' 'Emerald Pink,' 'Scarlet Flame' (rose-pink), and 'White Delight.' Moss pink is easy to grow. It performs best in sunny areas and well-drained soils. Shearing the plants back after flowering promotes dense growth and some rebloom. Moss phlox is useful for edging beds and as a groundcover for sunny slopes. It also looks nice planted amongst rocks or atop a wall.
Another low-growing phlox is Phlox stolonifera. Its common name is creeping phlox. (Phlox stolonifera is the "true" creeping phlox.) Plants are 6 to 12 inches tall and bloom in spring. Creeping phlox does best in moist, well-drained soils in partial shade. Excellent varieties include 'Blue Ridge,' 'Pink Ridge,' 'Bruce's White' or 'Ariane' (white with a conspicuous yellow eye), and 'Sherwood Purple' (purplish-blue). Creeping phlox is an excellent groundcover for partial shade. It also does well as an edging plant.
When browsing in garden centers this spring, be sure to check out the species and varieties of perennial phlox. They are excellent plants for home gardens.
This article originally appeared in the March 31, 1995 issue, p. 35.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on March 31, 1995. The information contained within may not be the most current and accurate depending on when it is accessed.