Phlox
Phlox is a flower in the Polemoniaceae family. It grows best in full sun with medium moisture, and is listed for USDA zones 2-13. Plants reach maturity about 70–85 days after planting and sit about 6 inches apart.
Varieties
1 from True Leaf Market · sorted by days to maturity▸21st Century Mix70–85 days
Non-GMO; AAS Winner; Container; Annual
70-85 days. 21st Century Mix phlox seeds are an adorable, compact, and vibrant addition to grow in your garden. 21st Century Mix phlox is durable and easy to grow from seed, as a charming border around the flower bed. 21st Century Mix phlox seeds boast tidy 10-12 inch compact mounds covered in dazzling 1-2 inch simple blooms.
View on True Leaf Market ↗
Plant spacing
In a square-foot bed, space phlox about 6 in apart — that fits 4 plants in each 1-foot square (2×2). Wider rows or containers space the same.
Plan your phlox planting
Add phlox to a free GardenDraft plan and get sow, transplant, and harvest dates computed for your ZIP code — with a drag-and-drop bed layout and reminders when it’s time to plant.
Start your free plan →At a glance
Growing timeline
Care & troubleshooting— extension-sourced, with citations
When to feed, prune & water
Attract beneficial insects and protect pollinators
Protection- Routine carePlant insectary flowers and tolerate light pestsstrong evidence — extension confidence
Grow a diversity of flowering plants (including small-flowered umbels and asters) to feed predators and parasitoids, and tolerate low pest numbers so natural enemies have prey to stick around.
- Routine careNever spray open bloomsstrong evidence — extension confidence
Avoid insecticides on flowering plants and apply any needed sprays in the evening when pollinators aren't active, and favor selective products over broad-spectrum ones to spare bees and beneficials.
Something looks wrong?
Describe what you see on your phloxand we'll rank the likely causes — most likely first, least-invasive fix first.
Powdery mildew
Diseasemoderate- CulturalImprove airflow + remove worst leavesstrong evidence — extension confidence
Cut out the most heavily coated leaves and thin for airflow; avoid wetting foliage late in the day.
- OrganicPotassium-bicarbonate or sulfur - label use only· every 1 wk · ~4 wksmoderate evidence — extension confidence
Apply a labeled potassium-bicarbonate or sulfur fungicide weekly per the label. No sulfur within 2 weeks of oil or in high heat.
Spider mites
Pestmoderate- CulturalHose down and raise humidity· every 3 days · ~2 wksstrong evidence — extension confidence
Mites thrive in hot, dry, dusty conditions. Spray foliage (especially undersides) with water to dislodge them and reduce dust.
- OrganicInsecticidal soap or horticultural oil - label use only· every 5 days · ~2 wksmoderate evidence — extension confidence
Apply to undersides per label; mites resist many products, so soaps/oils are preferred. Not in extreme heat.
Aphids
Pestlow- CulturalBlast off with water· every 3 days · ~2 wksstrong evidence — extension confidence
Knock colonies off with a strong jet of water in the morning; repeat every few days. Light infestations rarely need more.
- OrganicInsecticidal soap - label use only· every 1 wk · ~3 wksmoderate evidence — extension confidence
For persistent colonies apply insecticidal soap to undersides per label. Avoid open flowers.