How do I stop powdery mildew?

Ensure good air circulation and water at the base of the plant.

Yes, deadheading encourages a second flush of blooms.

Plant guide

Garden Phlox.

Phlox paniculata

Pronounced floks pan-ik-yoo-LAY-tuh

Also known as Fall Phlox, Fall-pink, Garden Phlox, Panicled Phlox, Perennial Phlox, Perennial-pink, Phlox, Summer Phlox

fall phlox — Photo by Tom Scavo (CC BY) via iNaturalist

Garden phlox is a classic perennial that brings height and fragrance to the summer garden. It produces large, showy clusters of flowers in shades of pink, purple, and white. These plants are favorites for attracting butterflies and hummingbirds to your yard.

At a glance

Care level: Moderate
Plant type: Herbaceous perennial
Light: Full sun to partial shade
Indoor light: Bright indirect
Water: Every 3 to 7 days
Mature size: 2 to 4 feet tall
Growth rate: Medium
Hardiness: USDA 4 to 8
Bloom time: Mid to late summer

Care

Plant in a spot with good air circulation to prevent powdery mildew on the foliage. Keep the soil consistently moist but not waterlogged to support healthy blooms. Watch for yellowing leaves or white dusty patches, which often signal moisture stress or fungal issues.

Watering: Water deeply at the base of the plant to keep the soil evenly moist during the growing season.
Feeding: Apply a balanced fertilizer once a month during the spring and early summer.
Pruning: Cut the stems back to the ground in late autumn after the foliage has died back.
Repotting: Divide the clumps every few years in spring to maintain plant vigor and prevent overcrowding.
Soil: Rich, moist, well-draining soil
Soil pH: 6.0 to 7.0
Temperature: -30 to 35°C
Humidity: 40 to 70%
Drought tolerance: Moderate
Lifespan: Perennial, typically 5 to 10 years.
Fragrance: Strong
Deer and rabbits: Low

Signs it needs repotting

Roots growing out of the drainage holes.
Water sitting on the surface of the soil for too long.
The plant stops growing even during the active season.

Safety

People: The plant is generally considered non-toxic, but ingestion is not recommended.
Pets: This plant is generally considered non-toxic to cats and dogs.
Children: The stems and leaves are not poisonous, but they are not meant for consumption by children.
Contact allergens: Some individuals may experience mild skin irritation from handling the foliage.
Airborne allergens: The pollen can be a minor irritant for those with severe seasonal allergies.
Edibility: This plant is not considered edible and should not be consumed.

How to identify it

Large clusters of fragrant tubular flowers
Opposite lance shaped green leaves
Sturdy upright stems reaching several feet
Distinctive eye in center of petals

Height: 0.6 to 1.2m
Spread: 0.45 to 0.9m
Leaves: green, deciduous
Flowers: pink, purple, white, red, 2 to 3cm

Problems to watch for

Powdery MildewCommon
Spider MitesCommon
Leaf ScorchUncommon
Leaf SpotUncommon
Stem RotUncommon
Root RotRare

By symptom

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Growing it

Propagation: division, cuttings, seed
When to plant: spring, autumn
Overwintering: Cut the stems back to the ground after the first hard frost to prevent disease overwintering. Apply a light layer of mulch if you live in a very cold climate.
In containers: It can grow in large pots, but ensure the container is at least 12 inches wide to accommodate the root system.

Division

Dig up the clump in early spring or fall.
Use a sharp spade to divide the root ball into smaller sections.
Replant the divisions at the same depth they were previously growing.

Planting in groups improves air circulation and creates a stronger visual impact.

Grows well with

Coneflower — They share similar light and moisture requirements.
Daylily — The contrasting foliage textures look lovely together.

Similar species

Creeping Phlox — It is a low growing groundcover version of the genus.

Science

Family: Polemoniaceae
Genus: Phlox
Order: Ericales
Class: Magnoliopsida
Native range: Eastern and central North America.
Conservation: This species is common and not of conservation concern.

It thrives in moist, fertile meadows and open woodlands where it competes for light.

Value to wildlife: nectar source
Pollinators: bees, butterflies, moths, hummingbirds
Uses: ornamental border, cut flowers, pollinator gardens

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Soil reaction: 6/9
Light: 7/9
Temperature: 5/9
Moisture: 6/9
Salinity: 1/9
Nutrients: 6/9

Taxonomy resolved against GBIF.

Questions people ask

How do I stop powdery mildew?: Ensure good air circulation and water at the base of the plant.
Should I deadhead?: Yes, deadheading encourages a second flush of blooms.

Where the name comes from

Phlox is Greek for flame, referring to the vibrant flower colors, while paniculata describes the panicled flower clusters.

Good to know

The name Phlox comes from the Greek word for flame.
These flowers are famous for their sweet, clove-like scent.
They are a favorite choice for traditional cottage gardens.

Keep your garden phlox growing

This page is a general guide. Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked.

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This guide was generated with AI and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.