Flower growing guide
Garden phlox
Phlox paniculata
Sun
Full sun
Season
Warm
Maturity
90 to 120 days
Water
Moderate
Soil pH
6.0 to 7.0
Spacing
18 to 24 in
Planting garden phlox
Plant divisions or nursery starts in spring or fall, spacing them generously for airflow. Seed-grown phlox takes a year or more to reach blooming size.
Planting details
- Spacing: 18 to 24 inches for air circulation
- Choose mildew-resistant cultivars in humid regions
- Divide every 3 to 4 years when centers thin out
Growing requirements
Garden phlox wants full sun and rich, evenly moist soil. Crowding and overhead watering invite powdery mildew, its main weakness, so give plants room from the start.
Harvesting and care
Deadhead for side shoots and a longer show. Thin clumps in spring and water at the base to keep mildew from starting on the lower leaves.
Common mistakes
- Crowding plants, which nearly guarantees mildew by July
- Watering overhead, which feeds the same problem
- Letting clumps go a decade without dividing, which hollows out the centers
Companion plants
Phlox stands beside bee balm, coneflowers, and daylilies in the midsummer border, where their heights and bloom times overlap.