How to Grow Phlox

how to grow phloxhow to grow phlox

Phlox comes in two forms – there is Garden Phlox (Phlox paniculata), which is an upright flower that grows to about three feet. Creeping Phlox (Phlox subulata), is a spring groundcover that stays green for most of the year. Both are easy-to-grow perennials that come back reliably every season.

Garden phlox blooms in mid summer and is a great addition to casual cottage garden landscapes, pollinator gardens, and is also at home in the shrub and perennial garden. The Creeping form blooms in mid spring and looks great as an edging plant to gardens, or falling casually over a low wall. Both Garden phlox and Creeping phlox produce fragrant blooms that attract a variety of pollinators, including butterflies and hummingbirds.

creeping phloxcreeping phlox
<a href="/perennials/phlox/creeping-phlox">Creeping Phlox</a> loves to spread and spill. Use it on slopes, banks, and in containers.
swallowtail on garden phloxswallowtail on garden phlox
Sweet-smelling <a href="/perennials/phlox/garden-phlox">Garden Phlox</a> is a favorite of butterflies, like this Giant Swallowtail.

When & Where to Plant Phlox

Phlox can be planted in spring or fall, and should be planted immediately upon receiving.

Light: Both varieties of phlox enjoy full sun, although the upright Garden phlox can take a little afternoon shade, particularly in the south.

Soil: Phlox is tolerant of most garden soils, but well-drained soil is preferable, particularly in northern areas where spring snow is slow to drain. Damp, waterlogged spring soil can rot the dormant roots. Add compost or peat moss to the garden to improve drainage and create a better overall environment.

Spacing: Garden phlox should be planted about 18 inches apart, while Creeping phlox should be planted about 2 feet apart. Giving these plants lots of room for air circulation is the key to limiting the appearance of mildew. (Although most varieties available today have been bred to resist mildew.)

Over the next few years you’ll see that both varieties form clumps that will gradually increase and join together to form one large grouping of phlox, with the Creeping variety creating a mat or carpet.

Planting in Fall: Fall plants can be kept cool on the deck for a few days until it’s convenient for you to plant, but don’t let the roots dry out and be sure to plant a few weeks before your first frost arrives.

Planting in Spring: Likewise, if the plant arrives in a container in spring, keep the container moist until the ground is ready to plant. Hold off on spring planting until the soil is free from melted snow and ice, and the ground is easy to work.

person holding phlox plantperson holding phlox plant
Start with a healthy Phlox plant with a strong root system.
person disturbing phlox rootsperson disturbing phlox roots
Disturb the roots before planting to encourage them to spread and reach.

How to Grow Phlox Throughout the Season

Growth Habit: Each spring you will see the dormant crown of Garden phlox start to emerge from dormancy and produce small green leaves. Keep the area weed-free and let the phlox just grow. Eventually, tall stalks will begin to shoot skyward from the base of the plant.

After a few weeks of spring sunshine, the Creeping phlox will be covered with colorful blooms. Flowers continue to be produced until the weather turns to summer heat but you might well find a few flowers come back when cooler late summer or fall weather arrives.

Staking: The clump of Garden phlox emerges with bright-green leaves that stay low until spring is well established and then begins to grow upward stems. The stems are quite strong and rarely need staking unless the plant is in an area of high winds or where animals can knock the plant over. If you decide to stake, do so early in the year, when the plant is still low to the ground, rather than when flowers begin to form.

  1. 'Fashionably Early Princess' Phlox

    Fashionably Early Princess' Phlox PP#28680 is the first one to the party, blooming in mid-spring before most garden phlox have even woken up. There's no waiting on this diva! Generou...

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    Fashionably Early Princess Phlox Fashionably Early Princess Phlox PP#28680 Phlox Fashionably Early Princess PP#28680
    $12.98 Sale $6.49
    Per Plant - 3" Pot
    Fashionably Early Princess' Phlox PP#28680 is the first one to the party, blooming in mid-spring before most garden phlox have even woken up. There's no waiting on this diva! Generous amethyst purple flower clusters attract pollinators and add charm to spring displays. Plant in rich, well-drained soil that receives sun to part shade. Exceptional mildew resistance. (Phlox paniculata)
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  2. Phlox Nicky, Garden Phlox, Phlox paniculata, Photo Credit Walters Garden Inc.

    'Nicky' is a fragrant garden Phlox with striking magenta-purple blooms that appear in mid-summer, attracting butterflies to its sweet scent. Tightly-clustered flowers, reminiscent of...

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    Nicky Phlox Garden Phlox Nicky Phlox paniculata Nicky
    $11.98 Sale $5.99
    Per Plant - 3" Pot
    'Nicky' is a fragrant garden Phlox with striking magenta-purple blooms that appear in mid-summer, attracting butterflies to its sweet scent. Tightly-clustered flowers, reminiscent of hydrangea blooms, are perfect for bouquets. Full, deep-green foliage and strong stems support the large flower heads. (Phlox paniculata)
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Watering: Although you’ll need to water young plants regularly until they become established, phlox in general do not require much water. During seasons with regular rainfall, your phlox should not need any extra water from the gardener. This drought-tolerant perennial will struggle with water-logged soil, so practice restraint with your hose!

<strong<Fertilizing:An application of general garden fertilizer each spring or spreading a fresh layer of compost or fine mulch over the garden each spring is about all these delightful plants need.

Mulching: The low-growing Creeping phlox emerges around the same time as the Garden phlox, but its whole mat starts to show little green shoots which quickly grow to produce early greenery in the garden. Even in areas where the plant does not go completely dormant, you’ll see bright new growth emerge. For this reason, mulch very lightly, so as not to smother out its needle-like foliage.

Phlox: End of Season Care

Trimming & Pruning: Deadheading the spent flowers of the summer blooming perennial keeps the plants healthy, and snipping off the flowers of the ground cover form keeps it looking neat. If you don’t have time or forget to deadhead or trim, the plants will forgive you and continue to bloom anyway. Each fall, after the frost has killed the top growth of your Garden phlox, trim the top dead growth and add that to the compost pile.

Trim the Garden phlox flowers and put into a vase on the table where they will hold up quite well for four or five days.

Dividing & Transplanting: Divide Garden phlox every 2-4 years in spring, to keep plants healthy and vibrant. Separate plants into sections, roots intact, with at least 3 active offshoots for replanting. Transplant with crowns one inch below the soil surface and eyes (offshoots) facing the sky.

Pests & Disease: Older varieties of Garden phlox can get mildew issues particularly in areas with warm, humid summers. Plants growing in part shade are more likely to get issues than those in full sun, but even full sun locations cannot stop the mildew appearing on the plant. If you're not planting a mildew-resistant variety, your first line of defense against powdery mildew is to properly space your plants in order to allow for good air circulation. Use a botanical fungicide if the problem is persistent (and/or read the article below). Creeping phlox does not usually have fungal issues.

Learn how to control powdery mildew on garden phlox.

Grow Phlox: Design Advice

pink phlox and white bee balmpink phlox and white bee balm
Phlox is a great companion, pairing nicely with many other flowering perennials. Here it is with Bee Balm.

Garden phlox is a perfect addition to any perennial garden - even a native garden, as most phlox have not been bred too far away from their native roots. Plant taller varieties toward the back of the garden bed where their height will not block you seeing smaller plants. They are perfect behind early blooming perennials such as Peonies which hide the early growth of the phlox stems. Phlox pairs nicely with contrasting flower types, such as spiky Russian Sage and the daisy-shaped blooms of Aster and Black Eyed Susan.

Plant small spring-blooming crocus bulbs close to the creeping phlox and as the phlox spreads the bulbs will continue to emerge through the green mat for added spring delight.

  1. Scarlet Flame Creeping Phlox, Phlox subulata

    'Scarlet Flame' Creeping Phlox ushers in spring vibrantly with its star-shaped, magenta-pink blooms. A drought-tolerant evergreen, this perennial groundcover creates a dense mat of 6...

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    Scarlet Flame Creeping Phlox Scarlet Flame Creeping Phlox Phlox subulata Scarlet Flame
    As low as $11.98 Sale $5.99
    Per Plant - 3" Pot
    'Scarlet Flame' Creeping Phlox ushers in spring vibrantly with its star-shaped, magenta-pink blooms. A drought-tolerant evergreen, this perennial groundcover creates a dense mat of 6 inch blooms atop needle-like foliage. Plant 'Scarlet Flame' in tricky areas like steep banks and rock walls to watch its flowers skillfully spread. Very cold hardy. (Phlox subulata)
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  2. Creeping Phlox Emerald Blue, Phlox subulata

    'Emerald Blue' Creeping Phlox is a fast-spreading, low-growing perennial groundcover that creates a carpet of pale lavender-blue flowers in spring. Extremely easy to grow, its early ...

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    Emerald Blue Creeping Phlox Emerald Blue Creeping Phlox Phlox subulata Emerald Blue
    As low as $11.98 Sale $5.99
    Per Plant - 3" Pot
    'Emerald Blue' Creeping Phlox is a fast-spreading, low-growing perennial groundcover that creates a carpet of pale lavender-blue flowers in spring. Extremely easy to grow, its early season blooms last for weeks and attract butterflies. Deer resistant and drought tolerant once mature. (Phlox subulata)
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  3. Purple Beauty Creeping Phlox, Phlox subulata

    'Purple Beauty' Creeping Phlox creates a mat of bright purple blooms paired with deep violet center eyes and grass-like foliage. This 4-6" tall spreading perennial flowers in the spr...

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    Purple Beauty Creeping Phlox Purple Beauty Creeping Phlox Phlox subulata Purple Beauty
    As low as $12.98 Sale $6.49
    Per Plant - 3" Pot
    'Purple Beauty' Creeping Phlox creates a mat of bright purple blooms paired with deep violet center eyes and grass-like foliage. This 4-6" tall spreading perennial flowers in the springtime under full sun, but can be planted under trees that leaf out and create shade later in the season. Drought-tolerant and deer-resistant, 'Purple Beauty' carries a sweet fragrance that attracts butterflies. (Phlox subulata)
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  4. Amazing Grace Creeping Phlox, Phlox subulata

    Amazing Grace Creeping Phlox welcomes spring with a flush of white blooms bearing a vibrant magenta eye. Petals may take on a flush of pink to complement the rosy highlights. Needle-...

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    Amazing Grace Creeping Phlox Amazing Grace Creeping Phlox Phlox subulata Amazing Grace
    As low as $11.98 Sale $5.99
    Per Plant - 3" Pot
    Amazing Grace Creeping Phlox welcomes spring with a flush of white blooms bearing a vibrant magenta eye. Petals may take on a flush of pink to complement the rosy highlights. Needle-like, evergreen foliage forms a dense mat making a lush groundcover perfect for cascading over walls or across slopes. Flowers attract butterflies to the garden. (Phlox subulata)
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