Fragrant phlox is easy to grow

By on March 25, 2011

Whether you call it downy phlox, prairie phlox or fragrant phlox, our native phlox, Phlox pilosa, carries a perfect Texas star at the center of each blossom.

Flower color ranges from the palest pink to the deepest lavender. The star in the center can range from clearly visible as a deep purple star in the middle of the lavender petals to a more ethereal set of star-shaped dashed lines at the throat of an almost white flower.

A mass of phlox

A mass of phlox (photo by Marilyn Sallee)

Many parts of this plant come in fives: Phlox has five fused petals, five sepals and five stamens. The exception to the fives rule is a little more difficult to see at first glance—an ovary with three fused carpels and a nectary disk at the base.

The common name of “downy” refers to the soft, fine hairs covering the long, narrow leaves. The leaves can be lanceolate to linear, approximately 3 to 4 inches long and half-inch wide and are arranged opposite up an unbranching stem. That single unbranched stem can send out tillers at the base to form clusters of connected plants with multiple stems and a deep taproot. This makes for a mounding appearance for the perennial that can reach 1-2 feet tall.

The pink to purple flowers appear in spring—March, April and May.

Another common name is fragrant phlox because of the deep, rich perfume it gives off to attract insects. The fist-sized clusters of dozens of half-inch wide flowers make a perfect landing place for nectar-seeking insects.

The deep, narrow throat that leads to the nectar disk seems designed for the long, curled proboscis of the butterfly. Painted ladies, swallowtails, sulfurs, cloudywings and other butterflies feast on the nectar. It attracts not only butterflies, but also skippers and moths, long-tongued bees and bee-flies, bumblebees and miner bees and cuckoo bees, too.

A variety of insects feed on the phlox, including the larvae of the spotted straw caterpillar (Heliothis phloxiphagu), phlox scarlet plant bug (Lopidea davis), four-lined plant bug (Poecilocapsus lineatus) and olive arches moth (Lacinipolia olivacea), among others. It’s also a food source for rabbits, deer and even groundhogs.

Downy phlox is easy to grow—in the right place. It does well in dry to moderately moist, well-drained soil, full sun or part shade. It is not picky about soil type, thriving in loam, clay, sand or rock. Under stress, the lower leaves turn yellow and drop off.

It can be propagated by stem cuttings in the spring or root cuttings in the fall after new leaves have reappeared. Seed production is prolific, and it throws tiny seeds abruptly, so tie a bag around the seed head to collect them. Germination of seed is unpredictable; they need cold stratification for at least a week at freezing temperatures.

In the language of flowers, the phlox means “our souls are united” or “we think alike.” It was commonly used in celebrations of union, such as weddings, family gatherings and working together for a common goal. According to folklore, planting it in the garden encourages family unity and harmony.

But while the folklore says “united,” the species itself is divided— into several subspecies, which freely hybridize. This makes subspecies markedly variable, with intermediates between the various subspecies possible.

For the  species of Phlox pilosa, the key trait is that it is a pubescent perennial that grows from a crown and the tips of the flower petals are not notched. There are many subspecies, with more subtle distinctions. But if you are putting off growing some of this butterfly-attracting native while you are thinking about the subspecies, another folklore use was in meditations to increase productivity and stop procrastinating.

Texas has many native phloxes

If you don’t have the right conditions for Phlox pilosa, you might try some of the other native phloxes:

One of Texas’ most beautiful wildflowers is Drummond phlox, P. drummondii, sometimes simply called annual phlox. It blooms in spring in a variety of colors from bright red to pink to white to lavender. This 6- to 20-inch-tall annual needs good drainage and grows in dappled shade to full sun in grasslands and open woodlands with neutral to moderately acid sandy soils.

P. roemeriana or goldeneye phlox is an annual endemic to dry rocky soils in the Edwards Plateau and High Plains.

You can find P. divaricata, sometimes called wild blue phlox or Louisiana phlox, in far East Texas near the Sabine River.

P. glabriflora or Rio Grande phlox grows from the Valley to south of San Antonio in deep well-drained sand.

Fall phlox, P. paniculata, needs full sun to part shade and moist loam, grows 3-4 feet and blooms in early fall.

Creeping phlox, P. stolonifera, only 6-10 inches tall, forms grass-like mats of spring flowers in moist shade or part shade.

Moss phlox, P. subulata, sometimes called thrift, is a very popular perennial. Evergreen moss-like mats bloom in spring and thrive in rocky, dry or sandy soil, in full sun or part shade.