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Planting and Growing Phlox

white phlox flowers
Image Credit:
Pixabay
Botanical Name
Phlox
Grown as
Perennial
USDA Zones
3a
3b
4a
4b
5a
5b
6a
6b
7a
7b
8a
8b
Toxicity
Non-toxic
Sun Exposure
Full Sun
Partial Sun
Shade
Water Needs
Moderate
Height
1–3 feet
Spread
1–3 feet
Soil pH
Neutral
Bloom Time
Spring
Summer
Flower Color
Blue
Pink
Purple
Red
White
Special Features
Container-Friendly
Cut Flower
Erosion Control
Fragrant
Long Blooming
Low Maintenance
Attracts Butterflies
Attracts Hummingbirds
Attracts Pollinators
Resilience
Clay Soil Tolerant
Cold Hardy
Plant Type
Flowers
Written By: Catherine Boeckmann Executive Digital Editor and Master Gardener

Looking to add a pop of color that butterflies love but deer won’t touch? Meet phlox—your new favorite flowering perennial. Whether it’s the candy-colored carpet of creeping phlox in early spring or the fragrant, tall blooms of garden phlox in summer, this versatile bloomer brings beauty to beds, borders, and everything in between. Ready to grow a garden showstopper that doesn’t mind a little shade or sun? Let’s dig into how to plant, grow, and care for phlox!

Bees, butterflies, and pollinators also adore phlox. And fortunately, phlox is deer-resistant, as deer do NOT like smelly flowers!

Planting

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.

Where to Plant Phlox

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. 

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.

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.

White, pink, and purple phlox flowers.

Growing

Watering

If you receive less than 1 inch of rain a week, remember to regularly water your plants throughout the summer.

Mulching

Each spring, put a thin layer of compost and a 2-inch layer of mulch around the plants to help keep the soil moist and control weeds.

Deadheading

Remember to remove the dead/faded flowers so that your plants can rebloom. Try out the Chelsea Chop!

Seasonal Care

If you have tall phlox, cut the stems back to about 1 to 2 inches above the soil after the first killing frost in the fall. (See local frost dates.) Divide tall garden phlox every 2 to 3 years to ensure healthy and disease-free plants.

Pests and Problems

Phlox Problems

Phlox is a colorful, pollinator-friendly perennial that is generally easy to grow. However, poor air circulation, overcrowding, and excess moisture can lead to disease problems, especially during humid weather.

Powdery mildew is one of the most common issues affecting phlox. Providing proper spacing, avoiding overhead watering, and cutting back stems after flowering can help reduce its spread. Choosing mildew-resistant varieties is also helpful.

Phlox Pests

Phlox may occasionally be affected by a few common garden pests.

Stem nematodes can damage stems and foliage, causing distorted growth.

Leaf miners tunnel through leaves, leaving visible trails and weakening plants.

Caterpillars may chew holes in foliage and flowers.

Phlox Diseases

Phlox can be affected by several fungal and soil-related diseases, especially in damp or crowded conditions.

Powdery mildew is common and appears as a white, powdery coating on leaves and stems; it is especially common during humid weather. Keep proper air circulation in mind when spacing out plants and avoid getting excess water on the foliage. Cutting back stems after flowering can also help to reduce the spread of powdery mildew, as can choosing mildew-resistant varieties.

Stem canker can cause dark lesions on stems, leading to wilting and dieback.

Rust causes orange or brown pustules on foliage and may weaken plants over time.

Southern blight is a soil-borne disease that can cause rapid wilting and collapse near the base of the plant.

Leaf spot diseases create dark spots or blotches on foliage, reducing the plant’s overall appearance and vigor.

Types

These perennials sport copious star-shaped, colorful flowers from spring through summer, depending on the variety. Because there are so many types (many of which are native to North America), you can find a phlox for almost any garden. Truly, their versatility can’t be overstated. 

  • Low-growing creeping phlox works great as ground cover in sunny yards.
  • Ankle-high woodland phlox is perfect for dappled, shady beds.
  • Medium-height garden phlox is often the “backbone” of the perennial garden, providing a layer of color midway through the garden and filling in gaps.
  • Tall garden phlox is excellent as a colorful backdrop, with large, often-fragrant flower clusters.

 

Wit and Wisdom

  • April’s Full Moon has traditionally been called the “Full Pink Moon” because it heralded the appearance of the “moss pink,” or wild ground phlox—one of the first spring flowers.
  • Medium and tall phlox are good companions for summer perennials such as lilies, bee balm, rudbeckia, Shasta daisies, yarrow, and clematis.

 

Flowers

About The Author

Catherine Boeckmann

Catherine Boeckmann

Executive Digital Editor and Master Gardener

Catherine Boeckmann loves nature, stargazing, and gardening so it’s not surprising that she and The Old Farmer’s Almanac found each other. She leads digital content for the Almanac website, and is also a certified master gardener in the state of Indiana.

Read more from Catherine Boeckmann

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Comments

<span>Lynnc</span> Sun, 05/06/2018 - 07:46
I also would like to know if I can control the height of phlox by trimming it a few times in May and early June. I live in NJ
<a title="View user profile." href="/author/editors">The Editors</a> Tue, 05/08/2018 - 10:53

Phlox is pruned back AFTER spring blooming season to help maintain the form you prefer. This is generally late May (after flowering).You want to make sure there are no buds left to open before you begin this process. Using garden shears, cut back the plant by a third or half. Do this annual after each spring blooming season and you'll get back on track.

 <span>Mary</span> Thu, 04/19/2018 - 13:45
I live in the Shenandoah Valley. My phlox gets 5 feet tall. Right now (4/18/18j it is around 6 to 8 inches. Can I cut them back to try and decrease the height?
<span>Brenda</span> Fri, 05/25/2018 - 21:31
We're in the Northeast. It's late May and phlox is already about 27-30 inches high no buds yet . Last year they got too tall. Should we cut back now to contain them.flowers were lovely but the height was unattractive.
<span>Kelly</span> Thu, 04/12/2018 - 14:06
I live in Ohio, it is mid-April, I never cut my Garden Phlox back. I see tiny buds on the plant...should I just leave it since it is already budding or should I cut it back? Thank you!
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 04/16/2018 - 17:07

Cut back phlox after bloom. Make sure all buds have bloomed. Generally, the time to cut back is late May (after bloom) to mid-August. 

 <span>Jeremy</span> Sun, 03/04/2018 - 19:54
I live in the Shenandoah Valley in Virginia. When can I plant Creeping Flock?
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 03/07/2018 - 16:05

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! 

 <span>Paula</span> Sat, 08/26/2017 - 22:48
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!
<a title="View user profile." href="/author/editors">The Editors</a> Thu, 08/31/2017 - 12:45

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.