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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>Wendy</span> Sun, 04/03/2022 - 12:00
I would love to know how to keep the tall wisps of grass out of my creeping phlox, too. Last year, I tried Preen Weed Preventer, but that didn't stop the growth of the grass.
<span>Em</span> Sun, 07/24/2022 - 09:06
The use of chemicals to kill noxious weed is both bad for our important insects and bad for our soil. I use landscape fabric or pieces of cardboard and then mulch on top of that. It’s far safer for our environment. Try it and you will be amazed while helping our earth at the same time! Happy gardening.
<span>Judy</span> Sun, 06/26/2022 - 11:15
Preen only kills weed seeds…not established plants. I believe there is a product called grass be gone by Ortho. Find that and read the bottle as to what it says about the using around your flowers..
<a title="View user profile." href="/author/editors">The Editors</a> Wed, 04/20/2022 - 11:26

Hi Wendy, thanks for writing in. We understand your frustration with the grasses that emerge through your beautiful groundcover. It certainly can be a nuisance. As an alternative to herbicides, which can be harmful to the plants you want to keep, we suggest adding a thin layer of compost and a new 2-inch layer of mulch around the plants in the spring to help control some of the grasses growing through. As the growing season continues, keep a watchful eye for grasses that do get through and remove them early.

 <span>Tom Backer</span> Wed, 05/05/2021 - 18:33
The plants are pretty big and I thought since it is end of blooming season here in Long Island NY, I can split them up in two, but not sure it can be done without killing them. They have very extensive roots, and are creeping phlox.
<span>Op</span> Thu, 04/15/2021 - 16:31
We did not prune our creeping phlox after last blooming season. left it as is & now after a cold winter ( not as much snow. but there were some cold days), the leaves are brown in most places. There is green sprouting here and there but not all over ( This is stretching over like say 12 feet - green shows up here and there) . Should we prune the brown ? It looks sad & I am not sure if it will grow green leaves in these spots. Any advise please
<span>Anne</span> Sun, 04/03/2022 - 11:33
pruning plants; I've heard Ralph Snodsmith; Horticulturist say; "anytime u have brown leaves or stems; prune the brown leaves and stems back";
<span>Patricia J Hunt</span> Wed, 03/31/2021 - 10:08
to start creeping phlox to spread, do I start at the top or middle of the area I want it to spread.
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 04/05/2021 - 14:14

Creeping phlox will creep towards sunlight. On a sloped or vertical surface, plant creeping phlox at the top so that it can hang and creep with the aid of gravity. 

 <span>Kathy R Purdum</span> Tue, 09/08/2020 - 12:24
I have several phlox on the east side of house. Have noticed that there are a couple areas where the phlox have turned completely brown . Should I completely dig those up or wait until next spring. We have not had much rain at all in our area. I have not separated them for a few years also. Please advise.