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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

<a title="View user profile." href="/author/editors">The Editors</a> Tue, 09/08/2020 - 15:37

If they normally perform well in those spots, it's likely just the lack of water that's causing issues. If you're able, give them some supplemental waterings in order to get them through autumn. Hopefully, next year will bring a bit more rain and they're spring back to life!

 <span>Renee</span> Fri, 08/21/2020 - 15:25
My tall phlox is spreading everywhere. Does it spread thru seed or through the root system? I have let some go in places I don’t want it and want to get rid of it but it’s trick in the rock landscape.
<a title="View user profile." href="/author/editors">The Editors</a> Mon, 08/24/2020 - 15:12

Tall garden phlox tends to spread by seed. To prevent this in the future, remove flowers once they've started to fade and before seeds are produced. If you pull out the unwanted phlox and are able to get most of the root system, it should not return.

 <span>Rita Rogers</span> Wed, 07/22/2020 - 23:13
Old remedy is to save your eggshells, of course rinse them off let them air dry, put them in a brown paper bag or a sandwich bag, whatever, and crush them up with a rolling pin or side of a glass. Sprinkle them around the base of your plants and the sharp edges of the eggshells will cut the snails. Yes, I know that sounds cruel but what do you want? That's how we grow down here in Texas.
<span>Rita Rogers</span> Wed, 07/22/2020 - 22:51
If you have used fertilizer, you added too much or it could be run off from fertilizing another plant but I've seen that with my cosmos. I fertilize something else and it ran off into my cosmos and that's how they looked. I betcha that's it. That's how it grows down here in Texas.
<span>Rita Rogers</span> Wed, 07/22/2020 - 22:45
To answer the question about flox in a container, knowing how fast those roots travel, my guess would be the flox are crowded.
<span>Debby</span> Sun, 06/28/2020 - 19:25
I live in Maine, by the ocean. This is the second year something has eaten the top of my Phlox. What is doing it?
<span>Laurel</span> Mon, 06/08/2020 - 20:40
Barry. Many of my phlox also don't have the bottom leaves. I suspect it is either slugs or black vine weevils, both of which come out at night. Slugs in particular munch the whole leaf away. I hunt them with a headlight at night, and capture them in folded up landscape material in the day.
<span>Barry Keller</span> Sun, 06/07/2020 - 13:38
One of my phlox plants, growing in potting soil in a large pot, each year loses its lower leaves. The leaves turn yellow and fall off. A plant pathologist could not identify any insect or mildew affecting the plant. I have tried to limit watering, sprayed with insecticde/fungicide, and divided the plant. The plant has been growing in partial shade but now moved now to full sun. The plant has been blooming but on largely leafless stems. Any thoughts?
<span>Joanne</span> Wed, 05/27/2020 - 14:28
I have phlox and I find stems laying on ground