Phlox plants are an old-fashioned flower, that deserves more recognition than it gets. The large clusters of flowers are very showy. Although some varieties will grow to 4 feet tall, the most common varieties are small, growing just up to 18 inches. The most common Phlox are annuals. There are also perennial varieties. Phlox is native to North America, from New York west to Michigan and south to Maryland. If you’ve never grown them before, growing Phlox flowers will be a rewarding experience.
Despite their small size, Phlox make good-cut flowers and are great in containers or window boxes. They will look great filling in a flowerbed, or as a border edging.
A native of North America, the jewel-like Phlox flowers grow in clusters at the top of the stems. These bright-colored blossoms include shades of red, purple, scarlet, yellow, and white, some with a flirty eye.
The name Phlox comes from a Greek word meaning “flame”.
Flower Colors: Lavender, lilac, pink, purple, salmon, and white.
Flowers Bloom: Summer to Fall frost.
Plant height: 2 to 4 feet tall.
Plant Hardiness Zone: 4 – 8
Did you know? Wild Sweet William is a specific variety of Phlox.
The plants are grown from seeds. Phlox seeds can be directly seeded into your flower garden.
For outdoor starts, sow Phlox seeds early in the season and cover lightly with 1/8″ of fine garden or potting soil. Water thoroughly once. Then, keep the soil moist while the seeds sprout.
Also, you can start them indoors for transplanting later. For early blooms, start the plants indoors six to eight weeks before the last frost. Young seedlings will transplant well into their permanent home.
Plants can also be propagated by division. Divide and replant clumps of Phlox right after the blooming period, or in early fall.
Transplant Phlox into your garden after the last frost date for your area.
Final Plant Spacing: Space plants 8-10″ apart. They will tolerate a little crowding.
Days to Germination: 10 – 20 days.
Phlox plants grow their best in full sun. However, they will do well in partial light shade, too.
They prefer rich, loose soil that drains well.
Keep the soil moist to slightly dry. Water them during dry periods, once or twice per week.
Add a general-purpose fertilizer when planting them, then once a month after that.
Once your Phlox plants are established, they should grow well with few problems. Keep the plants well-weeded. Then after they have grown a few inches, apply a 2–3-inch layer of mulch to help retain soil moisture and for a tidy appearance.
Pinch back tall stems to promote a bushier appearance.
Garden Tip: Remove spent blooms to promote additional blooms and extend the blooming period all summer long, and right up to the first killing frost. This will also keep the appearance neat and beautiful. More on Deadheading Spent Flower Blooms.
Hardy annual Phlox varieties often survive the first few light touches of frost. However, they will not survive a hard frost or freeze. perennial varieties go dormant after a killing frost, until next spring. At this time, you can cut the plants down to the ground.
Ideal Soil pH: 6.5 – 7.5.
Plant Problems – Identify the causes and find the cures.
Nematodes can be a problem when growing phlox. Treat early with insecticides specific to nematodes.
Disease problems are infrequent. If disease problems occur, treat early with fungicide.