Nothing beats the appeal of garden phlox plants. These tall, eye-catching perennials are ideal for sunny borders. In addition, the large clusters of pink, purple, lavender or white flowers bloom for several weeks in summer, and make excellent cut flowers. Growing hardy garden phlox is simple and so is its general care.
| Common name | Autumn Phlox, Cross-leaved Phlox, Fall Phlox, Garden Phlox, Perennial Phlox, Summer Phlox, Tall Phlox |
| Botanical name | Phlox paniculata |
| Family | Polemoniaceae |
| Species | paniculata |
| Origin | Eastern United States |
| Life cycle | Perennial |
| Plant type | Herbaceous Perennial |
| Hardiness zone | 4, 5, 6, 7, 8 |
| Sunlight | Full Sun |
| Maintenance | Medium |
| Soil condition | Clay |
| Soil ph | Acid |
| Drainage | Well-Drained |
| Growth rate | Medium |
| Spacing | 12 in. – 3 ft. |
| Harvest time | Fall |
| Flowering period | Summer |
| Height | 2 ft. – 4 ft. |
| Width | 2 ft. – 4 ft. |
| Flower color | Blue |
| Leaf color | Green |
| Flower benefit | Fragrant |
| Garden style | Butterfly Garden |
| Uses | Patio |
I. Appearance and Characteristics
Phlox paniculata is a species of flowering plant in the phlox family (Polemoniaceae). It is extensively cultivated in temperate regions as an ornamental plant and has become established in the wild in scattered locales in other regions. Common names include fall phlox, garden phlox, perennial phlox, summer phlox, and panicled phlox.
Fall phlox is native to parts of the central and eastern United States. It occurs as an introduced species in other parts of the United States, Canada,, Europe, and Asia. In the Chicago Region it is questionably native, or native populations may have all been destroyed: “populations in our area appear to be escapes from gardens to nearby woods and waste ground, which no doubt accounts for all collections since 1945”.
In its natural range, it grows along streambanks and in moist wooded areas.
Phlox paniculata is an erect herbaceous perennial growing to 120 cm (47 in) tall by 100 cm (39 in) wide, with opposite, simple leaves on slender green stems. The flowers are 1.5–2.5 cm (0.6–1.0 in) in diameter, often strongly fragrant and borne in summer through fall (autumn). The flowers are grouped in panicles (with many branching stems), hence the specific epithet paniculata. Typical flower colors in wild populations are pink or purple (rarely white).
Phlox paniculata is grown largely for its showy fragrant flowers in high summer. It requires a sheltered spot with full sun or partial shade, in fertile moist soil. Plants may be propagated by division or root cuttings in autumn, or by basal cuttings in spring.
Plants make excellent cut flowers. In hot, dry areas they are sensitive to powdery mildew, and affected stems should be removed immediately.
II. How to Grow and Care
Considering the value that garden phlox flowers add to a landscape, the care that they need is minimal. If located in a sunny spot and provided with a soil that drains well, they should thrive and come back year after year. Even their biggest problem, a disease known as powdery mildew, is rarely fatal but it can spoil their looks a bit.
Deadhead the spent flowers on garden phlox to prolong the blooming period. Regularly weed around your plant so that weeds do not sap its strength or rob it of the water it needs to get through the summer. Garden phlox attracts bees and other pollinating insects to the yard so you want to avoid spraying with insecticides or herbicides that can kill them.
Sunlight
Grow garden phlox in full sun in the North and partial sun in the South.
Temperature and Humidity
Garden phlox does not like hot, humid summers, so it is not a good choice for gardeners in the Deep South. You can mitigate problems of heat and humidity by adding mulch to keep the root zone cool.
Watering
Garden phlox should not be watered from above, but at the base or root zone. Watering from above can cause damage to the foliage. Furthermore, watering Garden phlox in the morning will help to keep its foliage healthy. Be sure to keep the soil moist and water regularly through dry summers.
Soil
Garden phlox does best in fertile , moist soil with the biggest requirement being good drainage.
Fertilizing
It is not essential to fertilize garden phlox. However, adding compost, manure, or peat moss will increase the fertility of the plant’s soil. Slow-release fertilizers are often thought to be best. Use it once in the spring and once in the late summer.
Pruning
This plant doesn’t need pruning in normal circumstances.
However, if there is a need to delay the bloom period, and if bushier foliage is required, cut back or pinch the stems back between one-third and one-half during the early summer.
Spend time deadheading spent flowers to extend the bloom time, which will also reduce the amount of unwanted reseeding.
When the plant experiences its first frost, it is ideal to cut the stems back just around the soil line and eliminate the foliage.
Propagation
Propagate phlox plants by dividing them in early spring. Dig your phlox plant out of the ground and split it into smaller clumps using a sharp knife. Then replant these clumps. You can also direct sow seeds in spring as soon as the ground can be worked. Cover seeds lightly with 1/8 inch of soil. Germination should occur in 5 to 10 days.
Potting and Repotting
If you plan to grow garden phlox in a container, you will need to pot it properly to provide the plant with optimal growing conditions. The best soil to use in a container is a potting mix, since this product drains well. Avoid using garden soil, which is likely to become compacted in a container. The result of compacted soil will be root rot caused by inadequate drainage, which can be fatal to your plant. Due to its height, garden phlox grown in pots may need staking or some other form of support.
Pests and Diseases
The major issue for the Phlox plant is the powdery mildew fungus which attacks the leaves of this plant and causing them to turn gray and become shriveled.
This disease problem is most common during high humidity in muggy hot summer days.
Spider mites are a problem in hot, dry conditions.
The plants placed under partial shade are also vulnerable to experience powdery mildew.
This issue is prevented by good air circulation by selectively thinning the stems of this plant to give it sufficient spacing and planting mildew-resistant cultivars.
While thinning the plant during the early spring, it is best to leave behind four to five strong stems.
III. Varieties of Phlox
There are many varieties of phlox, although people generally think of either the commonly-grown creeping phlox (Phlox subulata) or garden phlox (Phlox paniculata). Phlox subulata stays short and creeps, while the garden phlox is tall and upright. These two varieties serve different purposes in the garden. Creeping phlox is a ground cover, whereas garden phlox, with its greater height, is more likely to be found in the middle or back row of a flower bed.
Another difference between the two is that creeping phlox is a spring bloomer, while garden phlox is a summer bloomer. Furthermore, Phlox subulata have needle-like leaves, some of which remain green throughout the winter, while the leaves of garden phlox are much larger and die back at the end of the growing season; they are narrow at both ends and flare out in the middle.
Other types of phlox include:
- Drummond phlox (Phlox drummondii) is an annual species.
- Woodland phlox (Phlox divaricata): This perennial shares the feature of blooming in spring with creeping phlox, but its size is more reminiscent of garden phlox.
- Spotted phlox (Phlox maculata) is a perennial similar to garden phlox both regarding bloom time and appearance. It has less of a problem with powdery mildew than does Phlox paniculata.
IV. Uses and Benefits
- Ornamental uses
The garden phlox is commonly used in cottage, native, butterfly, and pollinator gardens as a border plant. Garden phlox is prized for its showy, bright fragrant flowers with a range of color combinations that bloom throughout summer to fall. This plant does particularly well in perennial borders as either a single specimen or in groupings. It is commonly planted alongside Black-eyed susan, Globe thistle, Red hot poker, and Coneflowers.
- Medicinal uses
The plant has been used medicinally, with the leaf extract serving as a laxative and to treat boils.
Find Where to Buy the Best Garden Phlox (Phlox paniculata)
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