Garden Phlox – Facts, Identification, Grow & Care

Garden Phlox is a herbaceous perennial wildflower native to Eastern North America that blooms from late summer to early Fall.  Scientifically known as Phlox paniculata, it grows 2-4′ tall in full sun and well draining soil. Blooming for six weeks in Summer to Fall, it attracts and array of butterflies, moths, and hummingbird moths.[1]

Garden Phlox begins blooming in Summer, but depending on conditions could still put out blooms into Fall. In fact that is how I first came across this species – it was still blooming in October in somewhat shady conditions.

 Facts

• The native range is from OK/NE, to Minnesota to Louisiana – and East to the Atlantic Ocean
• The Scientific Name of Garden Phlox is Phlox paniculata
• Also known as Fall Phlox or Tall Phlox, it is a perennial flower
• Blooms 1-2 months from late summer to Fall
• Garden Phlox is hardy from USDA zones 4-8, check you zone here
• Will attract late season butterflies, moths, and other small pollinators
• Tall Garden Phlox Attracts the Hummingbird Moths and Sphinx Moths! – It is always lots of fun to see those moths
• Not deer/rabbit resistant

Garden Phlox Reference Table
Common Name	Fall Phlox, Garden Phlox, Perennial Phlox, Tall Phlox
Scientific name	Phlox paniculata
Bloom Time	Late Summer / Early Fall
Bloom Duration	4-8 weeks
Color	Pink – Purple
Bloom Size	Clusters of flowers at the top of a stalk.  The cluster will generally be 4-6” tall and half as wide.
Characteristics	Individual flowers are about 3/4 “ wide (18 mm)
Height	2 to 4 feet tall (60-120 cm)
Spacing/Spread	2 to 3 feet (60-90 cm)
Light Requirements	Full Sun / Partial sun
Soil Types	Clay/Loam – just needs to drain well
Moisture	Moist to Medium, well drained
Maintenance	Deadhead flowers to prevent self-seeding
Typical Use	Manicured flower beds, woodland border, rain garden, near the edge of ponds.
Fauna Associations	Butterflies, moths, skippers, and other pollinators.  Deer/rabbits will browse Phlox
Larval Host	Several moth caterpillars feed on foliage
Sowing Depth	1/8” (3 mm)
Stratification	60 days cold stratification.  Or direct sow in Autumn/Winter – You need fresh seed!
Native Range	USDA Zones 4-8
Notes	This is a really pretty/petite fall flower

Garden Phlox Identification and Physical Description

Garden Phlox generally grows 2-4′ tall, depending on the conditions.  Studies have shown that the environmental conditions effect how Garden Phlox grows/flowers much more than its genetics.[2][3] I have around a half-dozen plants, and their colors go from white to dark magenta. They are all of similar height, but the sunlight conditions really effects when they begin flowering, as well as the number of blooms.

Stalk / Stem

It is erect and has no branching (most of the time) until the end, where the flowers will be located.  The stalk will be green, smooth and without hairs.

Leaves

Leaves are 3-6″ long and 1/2″-1.5″ wide and opposite.  They are lance shaped, or similar to a long tear-drop, with the leaf narrowing significantly as it approaches the tip.  There are generally veins on the surface.  The leaves are not serrated, but have extremely tiny hairs along the edges (ciliate) – but nowhere else. [4]

Flower

There will be a cluster, or pannicle of flowers at the top of the stalk.  Clusters will be anywhere from 2-6″ diameter, and kind of flat.  Individual flowers are pink with 5 petals and the center point of the flower will be tubular.  The number of petals is also a tell-tale identifier for this being a phlox, and not the dreaded invasive (but pretty) Dames Rocket. Colors can range from pale pink / white to dark pink / reddish or purple.

A couple of weeks after blooming seed capsules will form.  There will be about 3 leaves wrapping tightly around a small brown seed the size of a small pea.  Once it is dry enough, the capsule will kind of burst open and release the seed.

I’ve heard the capsules popping in brown bags I stored some seed heads in.  It is kind of funny when your are working on something in a quiet basement at 4 am, and all of a sudden you hear a random noise coming from a paper bag.

Once seeds are collected, they should be stored in a zip-lock bag in the refrigerator. I recommend winter-sowing the seed before the following Spring, as Phlox seed is notorious for being difficult to store for long periods of time. The viability doesn’t last as long as other types of flowers.

Root

Phlox paniculata has a taproot, and small rhizomes. It does not spread by rhizomes though, just increases itself in size a bit.

Garden Phlox Growing Conditions

Garden Phlox emerges in late Spring as just a tiny clump of leaves. Rabbits and deer will browse the plant at this stage, so consider protecting them with Liquid Fence (I use it, it works).

Sunlight requirements

Garden Phlox will thrive from full sun to partial sun, as long as it doesn’t dry out.  I have specimens in both, and they seem to grow to about equal height. Although if grown in full sun it will be showier and produce more flowers.

Soil/moisture conditions

Preferred soil types are anything with plenty of organic matter, however this particular species is tolerant of clay soil as well.  The key thing is that the soil should drain well, but not dry out. Garden Phlox is not drought tolerant and may require supplemental watering.

How to care for Garden Phlox

If you plant Garden Phlox in its preferred conditions, it should not require supplemental care.  You may need to apply liquid fence if deer/rabbits are a problem.  Other then that, just make sure the plant is spaced well to prevent powdery mildew from taking hold.  Because of the risk of powdery mildew, you should try to water Garden Phlox at the base on the plant, and not from overhead.

Maintenance

Deadhead flowers to prolong blooming and prevent self-seeding.  Or, don’t – it is up to you!  But if there isn’t much space between plants, and a lack of air movement, you can get powdery mildew on the leaves.

How to Establish Garden Phlox

If purchasing plants, just transplant it to the garden in an area that gets full sun to partial sun, and moist to medium soil moisture that drains well. A handful of compost added into the hole can help it establish more quickly.

If you have an area of the yard that is constantly wet, or puddles up after heavy rains, don’t plant it there! Keep an eye on the young plant for a week or two and make sure the soil stays at least somewhat moist.  After that, the plant should be good-to-go and take off on its own.

Purchase Seed

We have ordered a variety of native flower seeds from Everwilde Farms, which you can order right from Amazon through our link on our RECOMMENDED PRODUCTS PAGE. (We may earn a small commission when you purchase through our links, at no cost to you. This helps support our website.)

How to Grow Garden Phlox from Seed

To germinate seeds for Garden Phlox, you can do this fairly easily by just planting fresh seed about 1/8″ (3 mm) deep in the fall, directly where you want the plant to grow.  Just mark the location so you remember it in the Spring.

To start Garden Phlox from seed in pots, follow the steps below;

1. Get some Garden Phlox seed!  Gather fresh seed if you can.  Or, if purchasing seed online, store in the refrigerator in a sealed container if you aren’t stratifying it or planting it immediately.
   • If you don’t want to wintersow the seeds, then you must stratify them (simulating the winter).  To do this, store them in a moist paper towel in a zip-lock bag in the refrigerator for 60 days.  Alternatively you could use moist sand in a zip-lock bag.
2. Prepare pots for planting.  Fill pots with moist potting soil or seed starting mix up to about 3/4″ from the top (18 mm).
3. Plant Seed 3 mm deep.  Place seed on top of the soil, then cover seed with 1/8″ (3 mm) of soil.
4. Winter sow the seed.  Do this by covering the pot with a plastic dome or lid, with holes poked in it.  Set the pot outside in the winter.  Do this no later than January, as it generally needs 60 days of cold moist stratification.
5. Germination should occur in the Spring.  Grow and care for the young seedlings until they have a few sets of true leaves, and then plant out into the garden.  I’ve noticed that this germinated while temperatures were cold.

Garden Uses

Garden Phlox can make a great plant for a flower bed, moist wildflower garden or backyard micro-prairie.  The key thing is to plant it where it likes to live – full sun/partial shade and moist/medium, but well drained soil. 

It is tall, but not huge – which gives it some versatility in where you can plant it.  As a rule of thumb, it will stand out better if there are at least 3-5 plants in a cluster, spaced a couple feet apart.  Think of how much more dramatic a forest is rather than a single tree.

Click below to see our guide on making your own backyard micro-prairie!

Companion plants

Garden Phlox grows well with many different species of flower. Really anything that grows in full sun to partial shade and well-draining soil. If growing with taller species such as Joe Pye Weed or Ironweed, make sure the phlox is to the south of them so it doesn’t get shaded out.

For some companion plants that grow well with Garden Phlox:

• Cardinal Flower
• Blue Lobelia
• Black Eyed Susan
• White Turtlehead
• Mountain Mint
• Beebalm
• Bradbury’s Beebalm
• Wild Bergamot
• Self-heal

Fauna

Garden Phlox attracts a wide variety of pollinators, particularly butterflies and moths.[5]  Caterpillars from a couple of moth species will feed on the foliage, as well as some other specialty insects.

Pests and diseases

Deer and rabbits will eat the foliage.  So, it may be a good idea to spray with liquid fence if you notice any damage.

Powdery mildew has been documented to be a problem on this species.  Also, although leaf-spot fungus hasn’t been reported to be a common problem on this species, it has been documented to be susceptible to it.

Find more native plants here