Learn which plants thrive in your Hardiness Zone with our new interactive map!

How to Grow Phlox

By Dale Devries ; Updated September 21, 2017

Growing Phlox in a cottage garden is almost a must, but Phlox looks good just about anywhere. You can grow it in containers, window boxes and in your flower garden. It puts out many flowers that last from mid-summer through the fall. This plant is available in both annual and perennial varieties. The perennials will spread each year. Phlox is easy to propagate, so you can have more plants each year if you desire.

Choose a location for your Phlox. It should be in full sun to partial afternoon shade and should promote good air circulation. The more sun and air, the healthier the plant will be and the more flowers you will get from the plant.

Dig out areas where you want the Phlox to grow. The holes should be 4 inches in diameter and 4 or 5 inches deep for each plant.

Mix the soil with compost--one part compost to two parts soil. Place the mixture back into the holes, so the soil drains better and gives your Phlox added nutrition.

Plant seeds in the soil mixture in early spring but after the last threat of frost. Seeds should be at least 8 inches apart and a half-inch deep. For earlier plants, start the seeds indoors about two months before the last frost date. Transplant the seedlings into your mixed soil after all threat of frost has gone.

Fertilize with a light application of general-purpose fertilizer right after planting the seeds. Fertilize whether you are planting indoors or outdoors.

Water to keep the seed bed moist until the plants start to sprout. Water once or twice a week thereafter, depending on rain. Keep the soil moist to slightly dry. Phlox is prone to powdery mold, so the soil shouldn't remain wet.

Cover the ground with a couple inches of mulch after the plants have established themselves to keep down the weeds.

Snip off dead flower heads, taking a little of the stem, too. In the fall when the flowers have died off, cut the stems back to the ground. Discard of the cuttings in the trash or burn them because they might have mildew spores that could spread to other plants.

Take root cuttings in the spring and plant to add to your Phlox garden. The plant roots easily in well-composted soil.


Things You Will Need

  • Phlox seed
  • Compost
  • All-purpose fertilizer
  • Spade