Creeping phlox (Phlox subulata) puts on a stunning show of pink, purple or white flowers in the spring. It will quickly fill a wide or large container and cascade over the edges with long trailing stems. It is ideal for shallow containers because it has a shallow root system. Creeping phlox is also known as moss rose, moss pink and mountain phlox.
Creeping phlox forms an evergreen or semi-evergreen mat of foliage 3 to 6 inches tall and up to 24 inches wide. The numerous loose clusters of flowers are fragrant and last three to four weeks. Varieties are available with flowers in many shades of pink and purple, as well as white. The showy flowers attract butterflies.
Creeping phlox is hardy in U.S. Department of Agriculture plant hardiness zones 3b through 10. It grows in full sun in most areas but benefits from some afternoon shade in hot climates. It needs very well-drained soil and will grow in sandy or gravelly soil. Creeping phlox is tolerant of poor soils, drought and air pollution.
Choosing a Container
Because creeping phlox is a spreading plant, a wide or long container is suitable. Consider the size of the area where you will use the container and the number of plants it will contain; choose one that complements the style of your home and garden, such as casual, formal or modern. Styrofoam or plastic pots can be plain or fancy. Both types are lightweight, and the soil does not dry out quickly. Large clay pots are heavy and difficult to move. The soil in unpainted clay pots dries out quickly, while the soil in painted clay pots dries slower. Creeping phlox also adds interest when planted in alternative types of planters, such as wooden whiskey barrels, wagons and wheelbarrows.
Planting in a Container
Fill a clean container with porous, well-draining potting soil to within 1 inch of the rim. Remove the creeping phlox from its original pot and gently spread out the roots. Dig a hole slightly wider and deeper than the root system. Set the plant in the hole and cover the roots with soil; do not set the plant deeper than it was in its original pot. Use a gentle stream of water to thoroughly soak the soil until the water runs out of the drain holes.
Water creeping phlox in the morning so the foliage will dry before night to reduce the chance of diseases. Direct a gentle stream of water at the top of soil until it is thoroughly soaked. Continue watering until approximately 10 percent of the water drains from the pot to wash out the salts that have accumulated. Salts can damage or kill plants. Fertilize the plants if the leaves become yellowish or lighter green, notes the Perennial Resource website. Cut creeping phlox back by one-third to one-half after flowering to encourage denser growth and a second period of blooms.