Planting, Growing, and Caring for Phlox Flowers
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Planting
Because there are so many different types of phlox, sunlight requirements vary. Tall garden phlox do best in full sun, while woodland species thrive in partial shade. (See Recommended Varieties, below, for more information!)
In general, phlox prefer soil that is nutrient rich and evenly moist. They do not like to sit in wet soil, however. Use a garden fork or tiller to prepare your garden bed prior to planting. Loosen the soil to about 12 to 15 inches deep, then mix in a 2- to 4-inch layer of compost to improve soil consistency and fertility.
When to Plant Phlox
- Plant phlox in the spring after the threat of frost has passed, or plant in the fall at least a month before your first frost.
How to Plant Phlox
- It is easier to grow phlox from cuttings/transplants than from seeds, although established plants will readily spread by seed in the garden.
- Space plants according to their mature size.
- If you are transplanting a plant from a pot, dig a hole about twice the size of the pot’s diameter and place the plant so that the top of the root ball is even with the soil’s surface. Fill in around the root ball, and remember to water it thoroughly.
You just can’t go wrong with phlox! Here are some of the best species and varieties to try:
Low-Growing Phlox
- Creeping phlox or moss phlox (Phlox subulata) is a low-growing species that works excellently as a ground cover. It spreads slowly, growing in mounds that get 4–6 inches thick. The whole plant turns into a carpet of color in spring, when flowers cover every square inch of foliage. This phlox is particularly stunning when allowed to drape over a rock wall—imagine a waterfall of color! Creeping phlox grows best in well-drained soil and partial to full sun.
- ‘Candy Stripe’ is a popular variety with pink-and-white–striped flowers.
- ‘Emerald Blue’ produces a sea of lilac-blue flowers (perfect for that waterfall of color!).
- Phlox stolonifera, which also goes by the common names creeping phlox and moss phlox, is similar to P. subulata in name only. The main differences between it and P. subulata are that its leaves are oval-shaped (rather than needle-shaped), and its flowers are produced on stems that rise 6–10 inches above the foliage (rather than directly on the foliage). It prefers a shadier growing site with rich, evenly moist soil.
- ‘Sherwood Purple’ is a delicate little phlox with purplish-pink flowers.
- Woodland phlox or blue phlox (Phlox divaricata) is another low-growing species. As its two common names suggest, it prefers partial to full shade and moist, rich soils and produces bluish flowers in early spring. Like P. stolonifera, its flowers bloom on stems that rise about a foot or so above the creeping foliage.
- ‘Chattahoochee’ and ‘Blue Moon’ are two great varieties with beautiful blue-to-violet flowers.
Medium-Height Phlox
- Annual phlox or Drummond’s phlox (Phlox drummondii) grows as an annual rather than a perennial, unlike most other phlox species. Annual phlox rarely grows taller than 2 feet in height. Most varieties are not very heat tolerant, but in warmer regions, you may find the heat-tolerant varieties for sale. Plant in well-draining soil in a site that gets partial sun and doesn’t stay too wet.
Tall Phlox
- Garden phlox or summer phlox (Phlox paniculata) is the tallest phlox in cultivation and is probably the species that most folks have in their gardens. It grows in clumps that reach between 3 and 5 feet in height and produces panicles of flowers in mid- to late summer. Though tolerant of most lighting, it grows and flowers best in partial to full sun. It has a reputation for being very susceptible to powdery mildew, but resistant varieties are available.
- ‘David’ has bright white flowers and is resistant to powdery mildew.
- ‘Jeana’, another mildew-resistant variety, produces panicles of petite purplish flowers—similar in appearance to a butterfly bush.
Other Phlox
The phlox listed above are just a few of the many species out there. Others of interest to gardeners may be Carolina phlox (P. carolina), meadow phlox or spotted phlox (P. maculata), and sand phlox (P. bifida).
Catherine Boeckmann
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Hi Jeremy,
Depending on the type, you would plant spring-blooming phlox in the fall and fall-blooming phlox in the spring. Plant fall-blooming phlox in your region in the spring at least after the last frost of the season. We hope this helps!
Greetings!
I have 4 very tall plants growing in my garden. I planted some phlox last year and this 4 or 5 of the plants are at least 10 ft. tall. These plants have not bloomed yet, but look like the other phlox plants that have grown to about 4-5 ft tall. I don't remember plantings these tall plants. Do phlox get to 10 ft? I've been gardening for many years and have never seen phlox close to this tall. Thanks!
Apparently there are some pretty tall phlox varieties: Border phlox Phlox paniculata “David” is one; Mile High Pink Phlox is another; Caspian, Hesperis, Kirmeslandler, Old Cellarhole, Robert Poore, Russian Violet are others. Heights of these mention range from suggested 5 feet to about 6 feet. It may be that you have perfect conditions that inspire yours to reach even higher! As for how they got into your garden…an animal or bird may have transported the seed but it’s impossible to know for certain.
The Phlox I have is pink and white(Phlox paniculata ). It is quite tall--3.5- 4 feet. I just bought a pound of seed on line and plan on starting lots of new Phlox plots. The deer are not at all interested in it, so that is a plus! The plants have been coming back every year for many years; I just love em! I am careful to gather the seeds before the birds get them-- I buy plenty of seed for the birds all winter long.
I have moved them around and they seem hardy, requiring little or no care.
I'm wondering if I can plant these just alone in a separate spot ...will they grow into like a bush?
You should be able to achieve that effect, if the conditions—soil, sun, and water—are appropriate. Take note of the variety, ask questions about height, and you will not be disappointed. There are many varieties from which to choose (“ground cover” will not give you the desired effect).
My neighbor just gave me some tall Phlox that he dug up in his yard. It the middle of August it I replant them will they come back next spring?
You should have no problem. Phlox are perennial. Take note of the guidance above and be prepared to give it time to settle in.
I have tall phlox and am wondering if I can propagate them via ground layering?
The general guidance for propagating phlox seems to lean toward stem cuttings dipped in rooting stimulant powder.
The Virginia Cooperative Extension explains in detail:
Generally, tip cuttings are easier to propagate than root cuttings. Select second growth of phlox for cuttings. Make tip cuttings 3 to 6 inches long. Treat the base of the cutting with a root stimulant. Leave all foliage on the cutting except the part that will be below the soil line. Insert one cutting per peat pot. Place peat pots of tip cuttings in a lightly shaded place. Cover with a sheet of clear plastic. Check regularly to make sure the cuttings do not dry out. When cuttings do not pull easily out of the soil, they have begun to root. Make holes in the plastic sheet to increase the exposure of the cuttings to the air. This will harden the cuttings. Every few days, enlarge the holes or make new ones.
You can also make root cuttings of phlox. Dig the plants in late summer after they have bloomed. Select pencil-sized roots; cut them into 4-inch sections. Put each piece in a peat pot. Prepare a tray of peat pots as for seeds, except the soil mix should be 2 parts sand, 1 part soil, and 1 part peat moss. Water thoroughly.
