Phlox Care: Growing Garden Phlox, Creeping Phlox, and More
Phlox is a beloved genus of North American natives offering a variety of growth habits and bloom times, making them versatile garden performers. From the tall, fragrant flower heads of summer-blooming Garden Phlox to the ground-hugging mats of spring-blooming Creeping Phlox and the delicate beauty of Woodland Phlox, these plants provide vibrant color and often attract pollinators. Understanding the needs of the specific type you are growing is key, especially regarding light, moisture, and disease prevention.
Common Types of Phlox
Different species have quite different appearances and needs:
Tall Garden Phlox (P. paniculata)
- Classic border perennial (2-5 ft tall) with large, fragrant flower clusters in summer (pink, purple, white, etc.).
- Prefers full sun/light shade, moist, fertile, well-drained soil. Needs good air circulation to prevent powdery mildew. Hardy Zones 4-8.
- Examples include: 'David' (white, resistant), 'Jeana' (lavender-pink, highly resistant), 'Laura' (purple/white eye).
Creeping Phlox (P. subulata)
- Low, mat-forming groundcover (4-6 inches tall) with evergreen needle-like foliage. Masses of small spring flowers (pink, blue, white).
- Thrives in full sun and sharply drained, average/lean soil. Drought-tolerant once established. Hardy Zones 2-9.
- Examples include: 'Emerald Blue', 'Candy Stripe', 'Fort Hill'.
Woodland Phlox (P. divaricata) & Creeping Phlox (P. stolonifera)
- Woodland Phlox (P. divaricata): Loose clusters of fragrant, lavender-blue/white spring flowers. Prefers partial shade, moist rich soil. Native. Zones 3-8.
- Creeping Phlox (P. stolonifera): Similar habitat (moist shade). Spreads by stolons. Spring flowers (purple, pink, white). Zones 5-9.
Planting Phlox
Site selection depends heavily on the type being planted.
When to Plant
- Spring or Fall: Good times for planting perennial types.
Ideal Growing Conditions
- Light: P. paniculata: Full sun (best) to light shade. P. subulata: Full sun essential. P. divaricata / P. stolonifera: Partial to dappled shade.
- Soil: P. paniculata: Rich, moist, well-draining. P. subulata: Average/lean, sharply drained. P. divaricata / P. stolonifera: Moist, humus-rich, well-draining.
- Spacing: P. paniculata: 18-24 inches. P. subulata: 12-18 inches. Woodland types: 12 inches. Ensure good air circulation for P. paniculata.
Planting Technique
Match species to light/soil conditions.
Amend soil as needed for the specific type (compost for moist types; sharp drainage for creeping).
Dig hole slightly wider/same depth as root ball.
Gently remove from pot. Place in hole level with surrounding soil.
Fill hole, firm gently. Water thoroughly.
Good air circulation is vital for preventing powdery mildew on Tall Garden Phlox. Avoid crowding plants and consider thinning stems in spring.
Watering Phlox
- Tall Garden Phlox (P. paniculata): Requires consistent moisture throughout the growing season. Water deeply when top inch feels dry. Water at base.
- Creeping Phlox (P. subulata): Water regularly until established. Then quite drought-tolerant. Water only during prolonged drought. Needs excellent drainage.
- Woodland Phlox (P. divaricata/stolonifera): Prefers consistently moist soil in shade.
Fertilizing Phlox
- Tall Garden Phlox: Apply compost or balanced fertilizer in early spring. Light feed mid-season optional.
- Creeping Phlox: No fertilizer usually needed. Thrives in lean soil.
- Woodland Phlox: Appreciates rich soil. Top-dress with compost in spring.
Maintenance and Care
Thinning (Tall Garden Phlox)
- In spring (stems 6-8 inches), remove weaker stems from clump center, leaving 5-7 strong stems. Improves air circulation, reduces mildew.
Deadheading / Shearing
- Tall Garden Phlox: Deadhead spent clusters promptly for potential rebloom.
- Creeping Phlox: Shear entire mat back lightly after spring bloom to tidy and promote density.
- Woodland Phlox: Generally no deadheading needed.
Division
- Tall Garden Phlox: Divide clumps every 3-4 years (spring/fall) to maintain vigor.
- Creeping Phlox: Divide as needed if center is bare or to propagate (spring/fall).
- Woodland Phlox: Divide clumps spring/fall if desired.
Cleanup
- Cut back dead stems (Tall/Woodland) late fall or early spring. Creeping Phlox needs minimal cleanup.
Troubleshooting Common Problems
Powdery Mildew (Primarily P. paniculata)
Symptoms and Management
White powdery coating on leaves/stems, especially in humidity/poor circulation.
- Prevention: Resistant cultivars, full sun, air circulation (spacing, thinning), water at base.
- Control: Remove affected leaves if mild. Fungicides (horticultural oil, etc.) preventatively or at first sign if severe.
Spider Mites (Can affect P. paniculata in hot, dry conditions)
Symptoms and Management
- Tiny pests causing stippled leaves, fine webbing.
- Control: Water sprays, insecticidal soap/horticultural oil (cover undersides).
Root Rot (Especially P. subulata in wet soil)
Symptoms and Management
- Mushy crown, wilting, death.
- Cause: Poor drainage.
- Prevention: Provide sharply drained soil. Avoid overwatering.
Conclusion
Phlox offers diverse options for garden color from spring through summer. By selecting the right species for your site and practicing good cultural techniques like thinning (for Tall Garden Phlox) and shearing (for Creeping Phlox), you can enjoy these beautiful North American natives. Remember mildew prevention for Tall Garden Phlox is key!
