Annual phlox is an early-season bloomer that makes a great addition to containers or entryway plantings where its sweet fragrance can be enjoyed. The mounding, low-growing plant blooms in cheerful and bright shades of purple, pink, red, and white. Native to Texas, the plant attracts early pollinators such as bees, butterflies, and hummingbirds that are active during cooler weather.
Newer annual phlox cultivars bloom from early spring right through the heat of summer and then bloom again when temperatures drop in the fall.
Annual Phlox Overview
Where to Plant Annual Phlox
Plant annual phlox in a location that gets full sun, or mostly sun with some afternoon shade. The soil should be well-drained and slightly acidic to neutral.
Low-growing phlox forms a tidy mound of color at the feet of lofty spring bulbs so it is a good choice to pair it with other springtime bloomers such as tulips and daffodils. However, you can count on phlox to continue blooming long after the flowering bulbs drop their petals.
Another option is to plant it as a companion for spring-flowering shrubs. It quickly covers the soil around the shrubs with a splash of color, complementing the blooms overhead. Dwarf fothergilla, azalea, rhododendron, flowering quince, deutzia, and forsythia are some excellent spring shrub companions.
Annual phlox is a perfect addition to butterfly and hummingbird gardens.
How and When to Plant Annual Phlox
Start annual phlox from seed or buy starter plants at a nursery and plant them after there is no more danger of frost. Dig a hole about twice the diameter of the pots and about the same depth. Water the plants well in their pots and let them drain before placing them in the hole and backfilling with the original soil. Gently tamp down the soil and water well.
Space the plants 8 to 12 inches apart.
Annual Phlox Care Tips
Annual phlox is, just like its perennial cousin, an easy-care plant.
Light
Annual phlox blooms best in full sun. For varieties whose bloom extends into the summer, partial shade in the afternoon is beneficial.
Soil and Water
Annual phlox is not too finicky about soil but it needs to be well-drained, with a soil pH between 6.8 and 7.2.
While some varieties are moderately drought-tolerant, keeping the soil evenly moist ensures continuous bloom. Water when the top inch of soil is dry. Applying a 2-inch layer of mulch around the base of the plants helps conserve soil moisture.
Temperature and Humidity
Annual phlox blooms in the spring and fall when temperatures are cooler but there are new cultivars that have been bred with more resistance to heat; they bloom almost non-stop from spring through fall. The plant is not winter-hardy.
Fertilizer
In addition to amending the soil with lots of organic matter, fertilize the plants with an all-purpose slow-release fertilizer in the early summer to encourage extended flowering. For the amount to use, follow product label directions.
Pruning
Annual phlox typically doesn't require pruning. However, removing spent flowers (deadheading) encourages the plant to produce more blooms. This is also recommended if you do not want the plant to self-seed itself.
Potting and Repotting Annual Phlox
Select a pot with large drainage holes and fill it with well-draining potting mix. Keep in mind that potted plants need more frequent watering and fertilization than plants in the landscape. Water them at least daily in hot summer weather.
The lifecycle of annual phlox ends in the fall so it won’t require repotting.
Pests and Problems
Annual phlox is most affected by powdery mildew, leaf spot, and root rot, especially in a hot, humid climate. The plants can attract spider mites and the phlox plant bug. It has moderate resistance to deer browsing.
How to Propagate Annual Phlox
Annual phlox often reseeds itself, so it may not be necessary to replant it each year. Otherwise, direct seed annual phlox outdoors, which is the preferred method because the plants don’t transplant well. After the last spring frost when daytime temperatures reach at least 62 degrees F—or, if you live in a warm climate, in the fall—sow the seeds in a weed-free area. Cover the seeds with 1/8 inch of fine soil and keep the soil evenly moist. As the seedlings grow, thin them 8 to 12 inches apart.
Types of Annual Phlox
'Gisele' Series
This series withstands heat and has excellent drought tolerance. The plants of this series grow 12 inches tall and 18 inches wide.
- 'Gisele White' has clusters of pure white flowers in spring, summer, and fall.
- 'Gisele Pink' is a light pink flowering variety with a dark pink flower center.
- 'Gisele Hot Pink' has almost neon-pink blooms.
- 'Gisele Light Violet' is heat-resistant and blooms all summer.
'Popstars' Series
This series was also bred for its heat tolerance. The plants, which grow 12 inches tall and 16 inches wide, sport finely cut, star-shaped flowers.
- 'Popstars Red' has bright red blooms with crisp, pointed petals.
- 'Popstars Blue' has a mounding habit and purple flowers.
- 'Popstars Bright Rose with Eye' has pink flowers with a bright white center.
- 'Popstars Purple with Eye' has purple flowers with a bright white center.
Annual Phlox Companion Plants
Tulip
Early tulips, fringed tulips, species tulips, double tulips... there is no shortage of choices when it comes to these beloved spring bloomers. Critters like tulips just as much as humans do but other than protecting your precious bulbs with a fence, they are fairly low-maintenance plants. Zone 3-7
Daffodil
One of the easiest spring-blooming bulbs you can grow, daffodils are sturdy plants that bounce back after snowfalls and some also thrive in hot climates. And once you plant daffodils, they will reliably come back every year and multiply. Zone 3-9
Deutzia
In the spring, this shrub is covered with gorgeous, mostly white flowers (there are some pink-flowering cultivars as well). The many options for deutzia include small cultivars that fit even in the smallest of gardens, such as 'Chardonnay Pearls', which only grows 3 feet tall and 2 feet wide. Zone 5-8
Frequently Asked Questions
- How long does it take for annual phlox to bloom?Annual phlox starts blooming 50 to 65 days after the seeds germinate, which takes about 5 to 10 days after planting.
Annual phlox starts blooming 50 to 65 days after the seeds germinate, which takes about 5 to 10 days after planting.
- Is annual phlox toxic?Annual phlox is not toxic to humans and pets. However, it should not be consumed; it is not an edible flower.
Annual phlox is not toxic to humans and pets. However, it should not be consumed; it is not an edible flower.