Phlox are garden plants known for vibrant flower clusters and appealing fragrance. These versatile perennials offer diverse heights and bloom times, extending the flowering season from spring through late summer.
Planting and Care
Phlox cultivation begins with selecting the right location. Most varieties, including garden phlox (Phlox paniculata) and creeping phlox (Phlox subulata), thrive in full sun (at least six hours daily) for abundant blooms. Woodland phlox (Phlox divaricata) prefers partial shade. Adequate air circulation is important to prevent issues.
Phlox flourishes in moist, well-draining soil. Amend with organic matter like compost or aged manure before planting. Though adaptable to soil pH 6.0-8.0, a slightly acidic to neutral pH is ideal for creeping phlox.
Consistent watering is important to maintain moist soil. Phlox needs about one inch of water per week. Apply water directly to the base in the morning to reduce fungal disease. Established varieties show some drought tolerance, but regular moisture promotes best performance.
Phlox does not require heavy fertilization. Incorporating compost or a balanced slow-release fertilizer at planting is sufficient. For established plants, a light application of balanced fertilizer in early spring encourages vibrant blooms. A light feeding after the first flush of flowers can promote a second bloom.
Phlox Varieties
Phlox includes three main types: creeping phlox (Phlox subulata), garden phlox (Phlox paniculata), and woodland phlox (Phlox divaricata). Each offers distinct growth habits and bloom times.
Creeping phlox (Phlox subulata), or moss phlox, forms a dense, low-growing mat, 4 to 6 inches tall and spreading up to 2 feet wide. It produces a profuse display of flowers in shades of pink, purple, white, and blue, blooming for three to four weeks in mid to late spring. This variety is used as groundcover, in rock gardens, or spilling over walls.
Garden phlox (Phlox paniculata) is an upright perennial, growing 2 to 4 feet tall with a 2 to 3 foot spread. Its large, fragrant flower clusters bloom from mid-summer into early fall in white, pink, red, lavender, and purple. This type is used in borders and as a cut flower.
Woodland phlox (Phlox divaricata) prefers shadier conditions. It grows 1 to 1.5 feet tall, producing fragrant blooms in shades of blue, violet, and white in early spring. This phlox is suited for woodland gardens or naturalized areas with dappled sunlight and moist soil.
Pruning and Maintenance
Pruning and maintenance promote prolonged phlox blooming. Deadheading, removing spent flowers, encourages new blooms. This extends the flowering season, particularly for garden phlox, sometimes yielding a second flush. Snip spent blooms just above a healthy leaf joint or bud.
Pinching back stems in spring encourages bushier growth and more flower heads. This technique involves cutting back stems by one-third to one-half in late spring to early summer. This can delay flowering. For creeping phlox, prune after the main spring bloom to maintain shape and encourage rebloom. In late autumn or early winter, cut back perennial phlox stems to a few inches above ground to conserve energy and reduce fungal diseases.
Common Challenges
Phlox can encounter issues, mainly fungal diseases. Powdery mildew, a white, powdery coating on leaves and stems, is prevalent in humid conditions or with poor air circulation. This disease rarely causes plant death but can lead to leaf yellowing and premature drop. Adequate spacing and watering at the base rather than overhead prevent it.
Leaf spot, another fungal issue, appears as small, discolored patches on foliage. Remove affected leaves to limit its spread. Spider mites are common pests that infest phlox, causing stippled leaves with yellow or red spots. Addressing these challenges with proper care or treatments maintains plant health.