Year of the Phlox

Phlox is a wide-ranging North American native perennial and a common fixture in woodland, prairie, and meadow landscapes.

Overview and History

Phlox are an easy-to-find wildflower stretching from Florida and Quebec to Alaska. One of the classic American perennials, this was one of the earliest North American natives to enter cultivation. With vibrant flower colors and blooms lasting many weeks, it is easy to understand what caught the eye of so many gardeners through the years.

Although there is great variation within the genus, a tubular flower with five petals is common in all types. Flower color varies between white, pink, magenta, purple, and blue across the genus, with some species showing notable orange or red coloration. All species are popular with pollinators.

Basic Types and Variety Names

Phlox is a genus with a multitude of species, heights, bloom times, and garden applications. Many of these species are unrecognizable to the average gardener but becoming more common in newer varieties now available. Through all of the diversity, perennial Phlox can be loosely grouped into two types: spring bloomers and summer bloomers.

Spring Bloomers (Creeping/Groundcover types)

Phlox subulata (Creeping Phlox, Moss Pinks) and other early-spring blooming species are low-growing, ground-hugging plants. Typically native to rocky, well-drained environments, when put in a garden without restriction they become carpets of color. Most of these types tend to spread and work well as groundcovers.

Summer Bloomers (Tall Garden Phlox and related types)

When referring to Phlox, most first think of Tall Garden Phlox (Phlox paniculata). This clump-forming perennial blooms in midsummer and is among the tallest of this species. Also characteristic of Tall Garden Phlox are the perfectly formed large, rounded flower panicles that top each stem.

In addition to Tall Garden Phlox, summer-blooming species (including Phlox glaberimma and Phlox pilosa to name a few) are becoming more common, particularly in newer varieties. These newer garden varieties tend to bloom a bit earlier, have a more mounded shape, and have a stoloniferous habit. Also characteristic of summer bloomers is a propensity to rebloom after the first flush of flowers, particularly when trimmed back.

New Varieties and Series:

• LUMINARY™ Phlox paniculata – This mid-size series averages around 2½-3’ in height and shows excellent vigor and mildew resistance.
• Opening Act Phlox hybrid – A mid-height series of upright plants, averaging 2-2½’ tall. Excellent rebloom and mildew resistance.
• Fashionably Early Phlox paniculata – 2-3’ tall series bred for early & long-season of flower with rebloom in the fall.
• Jeana Phlox paniculata – A classic native selection with long panicles of compressed flowers; very popular with pollinators!
• Sweet Summer® Phlox paniculata  – Compact series of Tall Garden type at 1½-2’ tall with good mildew resistance.
• Super Ka-pow® Phlox paniculata – Early blooming compact series of Tall Garden Phlox at 1½’ tall with good mildew resistance.
• Woodlander – A series of low, spreading Phlox with large flowers.
• SPRING BLING™ Phlox subulata – This Creeping series has excellent garden resilience and a long season of bloom.
• ‘Drummond’s Pink’ Phlox subulata – An exceptionally vigorous Creeping series with large pink flowers.

How to Grow Phlox in the Garden

• The first thing to consider when putting a Phlox in your garden is the soil. All do well in sandy loam soil that has good drainage. Clay can be the kiss of death for Phlox as they struggle to root in heavy soils. One good workaround for clay soil is to build a raised bed and fill it with more neutral soil. The extra height will also improve the drainage and create an optimal growing environment.
• Consistent watering is helpful for plants trying to get established. Creeping varieties have low water requirements once settled in, only needing supplemental water when the days are at their hottest and longest in summer. Tall Garden types thrive with consistent watering. Adequate moisture will also help to prolong flowering and encourage rebloom.
• It is best not to overhead water your phlox plants. Overhead watering will increase the amount of moisture on the foliage, increase the humidity around the plants, and increase the presence of mildew affecting the plant. Mildew manifests as a white fuzz on the surface of the leaf that is both unsightly and will negatively affect the long-term health of the plant. Try to avoid wet foliage and water in the morning. It is best to water with a hose at the base of the plant or with drip irrigation. Drip irrigation helps to keep the soil wet and the foliage dry.
• Summer blooming plants can be encouraged to rebloom with consistent watering, adequate nutrients, and some deadheading. However, once Creeping Phlox (Phlox subulata) have finished flowering for the year, there isn’t anything you can do to get more flowers. Some of the spring species will have sporadic rebloom, but nothing close to when they were in peak.
• Full sun is the best growing environment for Phlox. With too much shade, Creeping varieties do not grow as dense and can melt away over time. Tall Garden types are more tolerant of light shade and do well in it, but when situated in full sun they tend to bloom more, have sturdier habits, and experience less powdery mildew.

10 Gardening Tips

1. Dividing the phlox every 3-5 years will help to reinvigorate the plant and improve garden performance.
2. With Tall Garden Phlox and other summer-blooming types, keep plants well-spaced to reduce issues with mildew.
3. Avoid overhead watering unless the plants will have a chance to dry out. An excess of moisture will increase the likelihood of powdery mildew.
4. Sandy loam is the preferred soil for all species, as it provides the good drainage these plants need to thrive.
5. More sun means more garden performance, both with increased floral production and sturdier, healthier habits.
6. Tall Garden plants thrive in rich soils and can be fertilized every other month if nutrition is a concern.
7. Deadheading Tall Garden plants will prolong the bloom time and prevent self-seeding.
8. Trim and clean up any dead foliage on your Creeping Phlox in early summer, just after they have finished blooming.
9. Fall is the best time to divide and replant Phlox.
10. Some species of Creeping Phlox are evergreen. On these plants, winter dieback should be cleaned up in spring, or early summer after they have finished blooming.

• How to Choose the Best Phlox by American Meadows
• Learn About Phlox by Burpee

Purchase Perennial Phlox at NGB Member Online Stores or Local Garden Centers

The National Garden Bureau recognizes and thanks Walters Gardens, an NGB member, as author and contributor to this fact sheet. 

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Each state in the U.S. has their own list of invasive species. Before trying a new plant in your garden, refer to the USDA’s National Invasive Species Information website or check with local agencies such as an Extension specialist.

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