Clouds of bright jewel-toned flowers and an easy-maintenance growth habit make garden phlox a favorite. This clump-forming perennial has upright stems clad in dark green, lance-shaped leaves. A mid- to late-season bloomer, garden phlox reaches its blooming peak in late summer and flowers into early autumn.It bears large, rounded-pyramidal clusters of fragrant, colorful flowers, often with contrasting central eyes. Flower colors include white, lavender, lilac, pink, rose, cherry red, and salmon.
Common name: Garden phlox
Botanical name: Phlox paniculata
Plant type: Herbaceous perennial
Zones: 4 to 8
Height: 2 to 4 feet
Family: Polemoniaceae, phlox family
- Sun: Full sun.
- Soil: Good garden loam with ample organic matter.
- Moisture: Evenly moist but not soggy. Water garden phlox at soil level to help prevent powdery mildew on foliage.
- Mulch: None, or a light 1-inch layer of organic mulch such as compost or shredded leaves.
- Pruning: Deadhead (remove fading flower clusters) regularly to encourage prolonged bloom and eliminate seed development. Cut plants back to the ground in late fall.
- Fertilizer: Fertilize annually with a balanced garden fertilizer.
- Divide clumps of garden phlox in early spring as new growth starts.
- Propagate root cuttings in a peat/perlite mix.
Pests and diseases
- Powdery mildew can be a serious problem on garden phlox. It appears as fuzzy white spots on the foliage. Minimize this fungal disease by selecting mildew-resistant cultivars, planting in sites with full sun and plenty of air circulation, and thinning the number of stems per plant.
- Root rot can develop in poorly drained soils.
- Garden phlox provides great color after early-summer bloomers like iris and delphiniums have finished flowering.
- The flowers of garden phlox add wonderful color to bouquets. Cut stems early in the morning, strip off leaves, and place in a container of warm water with floral food added. Let the flowers sit for an hour or more, then arrange in a vase.
- Seedlings that grow from cultivars usually revert to the magenta-purple flower color of the species, so deadhead regularly or pull out volunteer seedlings.
- ‘Bright Eyes'-light pink flowers with red eyes
- ‘David'-pure white flowers, moderate mildew resistance
- ‘Eva Cullum'-bright pink flowers with reddish eyes, fair mildew resistance
- ‘Franz Schubert'-light lilac flower
- ‘Laura'-bright reddish purple flower with white central star, moderate mildew resistance
- ‘Katherine'-lavender flower with white eye, good mildew resistance
- ‘Norah Leigh'-unique cream and green variegated foliage, lavender flowers
- ‘Prime Minister'-white flowers with red eye, good mildew resistance
- ‘Starfire'-bright cherry red flowers, fair mildew resistance
All in the family
- There are about 70 species of phlox, including annuals, perennials, and deciduous and evergreen types. Most are native to North America.
- Most popular phlox types for garden use include moss phlox (P. subulata), creeping phlox (P. stolonifera), woodland phlox (P. divaricata), and annual phlox (P. drummondii).
(Text by Nancy Rose, photo by Eric Agneessens)