Garden phlox
Phlox paniculata · Polemoniaceae Popular
Tall, often fragrant clusters of flowers that carry colour through the height of summer. Choose mildew-resistant cultivars and give plants good airflow.
- Size
- 3½ ft tall, 24 in wide
- Zones
- 4 to 8
- Light
- Full sun to part sun
- Flowers
- Mid July to early September
- Pets
- No toxicity recorded
- Job in a bed
- Drift
A bed built around garden phlox
The planner designed this bed around garden phlox when this page was made: a 12 × 6 ft (3.7 × 1.8 m) naturalistic planting in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why garden phlox stands where it does.
The plants
- 1 Garden phlox × 3, pink
- 2 Winter heath × 8, white
- 3 Dwarf lady's mantle × 9, green
- 4 Brown-eyed Susan × 3, yellow
- 5 Silver sage × 1, silver leaves
- 6 Quaking grass × 6, tan
- 7 Ornamental onion 'Purple Sensation' × 3, purple
- 8 Darwin hybrid tulip × 7, red
Why this plant
- The only dense clusters. The others are bells, airy sprays, daisies and others. Shape reads at a distance, where colours blur.
- The only pink.
Why here
- Anchors a back corner. At 3½ ft it is among the tallest plants here, and the tallest close the ends of the bed, where they stand in front of nothing.
- A step in the back row. Next to quaking grass (24 in): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for 8 weeks. From mid July to early September.
- Fills a gap. For one of those weeks nothing else on the plan is in flower.
Planned as a naturalistic planting: low grasses and groundcovers, the matrix, make up 42% of the planted ground. Cool colours (pink and purple) set against hot ones (yellow and red), with white, green and tan to calm things between them. The bed is tied together by its repeats: two kinds come round again along it, dwarf lady's mantle and winter heath.
The planner's own design check: 10 Excellent, 7 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where garden phlox goes in a border
At 3½ ft it belongs at the back of a bed. In the planner's ten height classes it is moderately tall (3 to 4 ft).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
Big domed heads give the border weight in high summer, and the scent carries in the evening. Its lower stems go bare, so plant something knee-high in front. Good air flow and a mildew-resistant cultivar keep the leaves clean.
- Height and scent at the back of a summer border
- Cottage gardens
- Cut flowers
What to plant with garden phlox
Plants recorded as good partners for it, and what each pairing does:
- Bee balm: in flower together for four weeks, from mid July; happy in the same moist soil.
- Daylily: purple against yellow, opposite each other on the colour wheel, if you choose those colours, in flower together for four weeks.
- Purple coneflower: in flower together for eight weeks, from mid July.
Questions about garden phlox
Does garden phlox need sun or shade?
Garden phlox grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).
It wants soil that stays evenly moist, rich in organic matter, and a good soak in dry spells.
What zones does garden phlox grow in?
USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does garden phlox flower in my zone?
In zone 5 it flowers mid July to early September. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 4 | Late July to early September |
|---|---|
| Zone 5 | Mid July to early September |
| Zone 6 | Mid July to early September |
| Zone 7 | Mid July to early September |
| Zone 8 | Mid July to early September |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should garden phlox be planted?
24 in (60 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.
It grows 3½ ft (100 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many garden phlox plants do I need?
At 24 in apart, set out in staggered rows:
- 3 to fill 10 square feet (about 1 m²)
- 6 for a single row 10 ft (3 m) long
- 10 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used three in one group.
Is garden phlox poisonous to dogs and cats?
No toxicity is recorded for dogs, cats, horses or people, according to NC State Extension.
"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.
Do deer eat garden phlox?
They may. NC State does not list it as resistant to deer or rabbits. Where they visit, protect it, or plant it among ones they avoid.
What flowers after garden phlox?
Garden phlox is over by early September. These start as it finishes and carry the same spot on, so it never goes flat:
- Garden chrysanthemum: from mid September to late October, 24 in tall, to stand in front of it and cover its fading stems.
- Blue mistflower: from late August to mid October, 2½ ft tall, to stand in front of it and cover its fading stems.
- Blue-stemmed goldenrod: from early September to mid October, 2½ ft tall, to stand in front of it and cover its fading stems.
What does garden phlox look like in winter?
Garden phlox dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
Is garden phlox good for bees and butterflies?
Garden phlox is visited by pollinators, bees, butterflies and hummingbirds.
It is native to the United States.
More Phlox
- Creeping phlox Phlox subulata
- Creeping phlox 'Candy Stripe' Phlox subulata 'Candy Stripe'
- Creeping phlox 'Emerald Blue' Phlox subulata 'Emerald Blue'
- Creeping phlox 'Sherwood Purple' Phlox stolonifera 'Sherwood Purple'
- Creeping woodland phlox Phlox stolonifera
- Garden phlox 'Bright Eyes' Phlox paniculata 'Bright Eyes'
- Garden phlox 'David' Phlox paniculata 'David'
- Garden phlox 'Jeana' Phlox paniculata 'Jeana'
- Garden phlox 'Laura' Phlox paniculata 'Laura'
- Woodland phlox Phlox divaricata
- Woodland phlox 'Blue Moon' Phlox divaricata 'Blue Moon'
In these guides
- Plants that grow near black walnut
- Pet-safe plants for a sunny border
- Native perennials for pollinators
- Plants for hummingbirds
- Plants for butterflies
- Plants for bees
- Plants for a white garden
Every fact on record
- Type
- Perennial
- Size
- 3½ ft (100 cm) tall, 24 in (60 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back
- Flowers
- Mid July to early September; dense clusters; pink, white, purple
- Leaves
- Medium texture, herbaceous; green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 4 to 8
- Light
- Full sun, part sun
- Soil
- Rich, evenly moist
- Water
- Moderate
- Feeding
- Moderate, in spring
- Family
- Polemoniaceae
- Comes from
- Eastern United States
- Attracts
- Pollinators, bees, butterflies, hummingbirds
- Stands up to
- Black walnut
Checked against NC State Extension and VASCAN (plants of Canada). Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.