Phlox

( FLOX )

At-A-Glance Information

Phlox is a genus of flowering perennial and annual plants that need full sun or light shade and regular water to perform well. They are commonly referred to as Phloxes, and their frequently fragrant flowers will attract butterflies and other pollinators to the garden. Most species are native to North America and have showy flower clusters. These small shrubby plants come in many different sizes, shapes, colors and habits, and are therefore great for a wide variety of uses in the garden, including as members of container or rock gardens, in cottage, informal, or pollinator gardens, or simply as specimens to add pops of color in mixed beds and borders.

Phlox Species and Varietals

The genus Phlox is a member of the plant family Polemoniaceae and includes around 68 species. Plants in the genus are related to those in Polemonium (Jacob's Ladder), Ipomopsis (Scarlet Gilia) and Gilia. The genus name is derived from the Ancient Greek word φλόξ (phlóx, pronounced 'flox') meaning 'flame', referring to the vibrant, fiery colors of their flowers. Phlox growing zones vary depending on the species. For more information, see the descriptions below, To find your zone, click here: Zone Map.

Phlox adsurgens (Northern Phlox, Woodland Phlox)
This native of the western United States prefers to grow in woodland and forested areas. It is a decumbent perennial that reaches about a foot tall when mature, and produces clusters of pink flowers. This is a popular garden ornamental plant and is suited for USDA hardiness zones 4-9.

Phlox bifida (Sand Phlox, Cleft Phlox, Ten-Point Phlox, Starry Phlox)
This species grows in USDA hardiness zones 4-8 or Sunset growing zones 2-17 and is native to the central United States. It forms clumps or mats of light green foliage and blooms in spring through early summertime. Flowers are profuse and are lavender to white. This species thrives in direct sun with great drainage. It can tolerate drought conditions, but does prefer moderate waterings. Individual plants reach between 6 and 12 inches tall when in bloom. Cultivars include 'Snowmass' (with white blooms and mats of green foliage), 'Starbright' (with lavender-blue deeply narrow petals), 'Alba' (with white fragrant flowers), and 'Betty Blake' (mat-forming to 3 inches tall with dark lavender blooms).

Phlox carolina (Thickleaf Phlox, Carolina Phlox, Giant Phlox)
This species of Phlox grows in USDA hardiness zones 5a-9b or Sunset growing zones 1-14 and 18-23, and is native to central and eastern United States. To 3 feet tall and half as wide. Flowers are pure white and fragrant, blooming in early summertime. This is a heat tolerant Phlox that is mildew resistant and makes great cut flowers. Cultivars include 'Miss Lingard' (also called Wedding Phlox, with fragrant pure white blossoms), 'Kim' (to 2 feet tall with light pink flowers), 'Magnificence' (to 3 feet with dark pink flowers), 'Minnie Pearl ' (with white flowers), 'Bill Baker' (mat-forming with lilac-pink blooms) and 'Gypsy Love' (with pink flowers).

Phlox diffusa (Spreading Phlox)
These plants are native to western North America and form mats of foliage. Spreading Phlox grows well in USDA hardiness zones 4-8. These subshrubs rarely exceed 8 inches in height, and produce needle-like leaves. Flowers are lavender to pink in color and are relatively showy for the plant's small size.

Phlox divaricata (Wild Blue Phlox, Wild Sweet William, Woodland Phlox)
This perennial species is best in USDA hardiness zones 3-8 or Sunset growing zones 1-17 and is native to Eastern North America. It reaches a foot tall and twice as wide and has creeping underground stems. Spring flowers form in fragrant clusters in various colors from pale blue to white, sometimes blushed with pink. Great for rock gardens and containers, and frequently used as a bulb cover plant. Needs good, deep soil and light shade for best performance. Varieties are listed below.

'Dirigo Ice'
Pale blue blossoms.

'May Breeze'
Pale blue flowers.

'Blue Moon'
Violet-blue flowers.

'Montrose Tricolor'
Lavender-blue flowers with pink new foliage that ages to green with white margins.

Phlox divaricata laphamii 'Chattahoochee'
Pale lavender blossoms with purple eyes.

'Clouds of Perfume'
With lavender flowers that have a wonderful fragrance.

'White Perfume'
With fragrant white flowers.

Phlox drummondii (Annual Phlox, Drummond's Phlox, Pride-of-Texas, Texas Pride)
This annual species grows best in USDA hardiness zones 2-11 or Sunset growing zones A2, A3, 1-24 and H1. It is native to Texas and reaches 6-18 inches tall and has sticky hairs on its foliage. Blooms profusely in tight clusters in a variety of bright and pastel colors. This species prefers light, rich soil amended with organic matter. Needs full sun. Plant in spring in cold winter areas and in fall in fall in milder climates. These plants are sometimes seen growing in disturbed areas, old fields and roadsides. Some varieties have a contrasting-colored eye. Cultivars and strains are outlined below:

Fordhook Finest Strain
1.5-foot tall plants with a mix of colors.

Intensia Strain
Heat and drought tolerant plants that reach 8-12 inches tall and take a rounded shape.

Beauty Strain
Rounded flowers on this dwarf strain that reaches just 6-8 inches tall.

Globe Strain
6-8 inch tall plant with rounded flowers.

Petticoat Strain
With star-shaped blossoms.

Twinkle Star
Star-shaped blooms.

Phlox maculata (Thick-Leaf Phlox, Meadow Phlox, Marsh Phlox, Wild Sweet William, Spotted Phlox)
This species of Phlox grows best in USDA hardiness zones 3-8 or Sunset growing zones 1-14 and 18-23, and is native to Eastern North America. It reaches 3-4 feet tall and 1.5 feet wide, with flowers that bloom in early summertime. Colors range from white through shades of pink and foliage is shiny. Cultivars are listed and described below:

'Alpha'
With rose-pink flowers.

'Delta'
White flowers with a pink eye.

'Natascha'
Pink and white bicolored flowers that form a pinwheel pattern.

'Omega'
White flowers with a pinkish purple eye.

Phlox paniculata (Summer Phlox, Fall Phlox, Garden Phlox, Perennial Phlox, Panicled Phlox, Tall Phlox)
This herbaceous perennial species of Phlox is best in USDA hardiness zones 4-8 zones 1-14 and 18-21, and is native to eastern United States. It reaches 3-5 feet tall and 2 feet wide. Leaves are narrow and pointed, and summer flowers bloom in clusters of pink, lavender, rose or red, some with a contrasting eye. These flowers love full sun, though this exposure can mean that bloom color is bleached out; if you have this issue, provide your Phlox with some shade and the color should return. Pinch stem tips when the plants are young to encourage a more bushy growing habit. Divide these plants every few years to increase air circulation and improve performance. This species is susceptible to powdery mildew, so air flow is key; divide plants every so often, and thin mature plants so that they only have a few shoots per plant. There are many cultivars of Summer Phlox; some of the most commonly grown are listed below:

'Miss Marple'
White flowers with red-pink eyes.

'David'
Pure white blossoms.

'Eva Cullum'
Pink with a red eye.

'Miss Pepper'
Pink with a red eye.

'Miss Candy'
Bright, vivid pink flowers.

'Pink Red Eye Flame'
Deep pink with a red eye.

'Bright Eyes'
Rose-pink flowers with a darker eye.

'Laura'
Pink-purple with a white eye.

'Miss Violet'
Flowers are purple.

'Blue Paradise'
Blue-violet flowers.

Volcano Series
Flowers in this series come in red, lavender, pink with white eyes, and pink with red eyes.

Phlox stolonifera (Creeping Phlox, Moss Phlox, Creeping Woodland Phlox, Star Rock Phlox)
This species of Phlox grows best in USDA hardiness zones 5-9 or Sunset growing zones A2, A3 and 1-17, and is native to eastern North America. It has a creeping, mounding habit to 6-8 inches tall and a foot wide, with evergreen foliage and profuse flowers in springtime. This species needs partial shade for best performance. Varieties include 'Bruce's White' (with white flowers), 'Blue Ridge' (lavender-blue flowers), 'Home Fires' (rich pink flowers) and 'Sherwood Purple' (deep lavender flowers).

Phlox subulata (Moss Pink, Creeping Phlox, Moss Pink, Mountain Phlox)
Best in USDA hardiness zones 3-9 or Sunset growing zones 1-17; native to the Eastern United States. Forms a 6 inch tall mat that creeps to a foot or wider, with needlelike evergreen foliage. In late spring or early summer, profuse blooms appear in white, pink, or lavender-blue. These plants enjoy loose, semi-rich soil and moderate water. After flowers fade, cut back about halfway. It is relatively drought tolerant, and has a good fall rebloom if sheared. Variety 'Tamanonagalei' (also called 'Candy Stripe') has rose-pink blossoms edged in white. The fragrance of these plants is sometimes mistaken for that of Cannabis plants.

Caring for Phlox

Phlox flowers do well when grown in full sun to partial shade, though there are some species, such as Woodland Phlox (Phlox divaricata) that can take heavy shade and still perform well. They appreciate a well-draining soil that is rich in nutrients and has a pH of between 6.0 and 8.0. If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a thick (1-2 inch) layer of mulch around new plantings to increase soil moisture retention, suppress weed growth, and maintain consistent soil temperatures. Water newly planted Phlox regularly as it establishes a root system in its new home. At maturity, Phloxes are considered to be somewhat drought-tolerant, but do perform better with regular water, especially during their active growing seasons in spring and summertime. As a rule of thumb, irrigate whenever the top inch or two of soil feels dry to the touch.

To fertilize, simply apply a dressing of compost around the base of the plant each year in springtime. Pull back mulch before applying, and replace after compost has been worked into the soil a bit. Phlox plants do not typically need pruning, but spent blooms can be deadheaded to clean up their appearance and encourage more flowers to form. Once the flowering season has ended, the entire plant can be cut back and will regrow the following spring. If you are looking to collect Phlox seeds for propagation, make sure to leave some seed heads on the plant to mature. Phlox flowers are perennials, and can last in the landscape for decades if cared for properly.

Caring for Phlox in Containers
Phlox flowers do well in the ground, but can also be grown in containers where their delicate flowers and foliage can be admired. Choose a container that is at least a few inches wider and deeper than the nursery pot or root ball. Ensure that the pot has adequate drainage holes on the bottom to allow for excess water to flow away. Fill with a well-draining potting mix amended with organic material and perlite, and top with a layer of mulch to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water regularly as the plant establishes itself in its new home. Once established, waterings can be lessened. Phlox plants grown in containers will need more frequent irrigation than those grown in the ground. As a general rule of thumb, water whenever the top few inches of soil feels dry to the touch. Prune to remove dead, damaged, or diseased foliage at any time during the growing season. Every few years, check the bottom of the pot to ensure that the plant is not outgrowing its root space. If roots are growing through the drainage holes in the bottom of the container, it is a good indication that it needs to be potted up; choose a slightly larger container and repot.

Propagation

Phlox can be propagated either by division or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Phlox, follow the instructions below:

Propagating Phlox by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
In either late winter or early springtime, get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-3 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Phlox by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil, compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring (after the plant has entered dormancy, but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance. To propagate by division, follow these steps:

Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section attached.
Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.