Garden Phlox Care Guide: How To Grow Phlox Plants For Billowing Plumes Of Fragrant Flowers

Nothing beats the appeal of garden phlox plants. These tall, eye-catching perennials are ideal for sunny borders. In addition, their large clusters of pink, purple, lavender, or white flowers bloom that make excellent cut flowers.

These elegant plants begin blooming in early summer and reward gardeners with a profusion of flowers that last well into fall. Growing hardy garden phlox is simple and so is its general care, so they're a great low-maintenance option for unfussy gardeners.

Common garden phlox one of our experts' favorite plants as well as one of the all-around best perennial flowers you can grow. Follow this complete care guide to learn how to grow garden phlox for yourself.

Is Garden Phlox Like Other Phlox Types?

Before learning how to grow phlox plants, gardeners will need to differentiate between some of the most common phlox varieties. How to grow tall phlox varies from how to grow creeping phlox. Cultural conditions also play a role for those hoping to learn how to grow annual phlox, as well as perennial types.

This can be especially confusing to new growers, or those simply making use of the plants’ common name. The specific needs and requirements for growth of Phlox paniculata can be found below.

Garden Phlox Care

Garden phlox (Phlox paniculata), also called summer phlox, is a sun-loving perennial with a long flowering season. Large clusters of flowers, called panicles, sit atop stems that grow 3 to 4 feet (0.9-1.2 m) tall. This knockout native flower thrives in USDA plant hardiness zones 4 to 8.

Let's take a look at how what your garden phlox needs to grow in more detail.

Light

To perform their best, phlox will require full sun throughout the day. This means that plants should receive at least 6-8 hours of direct light. Several garden varieties will benefit from partly shaded conditions, in which flowers are sheltered throughout the hottest parts of the afternoon.

Temperature & Humidity

Tall phlox prefer cool growing temperatures. This is especially true in spring and early summer as the plants prepare to flower. Warmer temperatures will slow growth, sometimes resulting in stress should they climb.

High humidity may also be of special cause for concern. Growing hardy garden phlox is a challenge in hot, humid areas because the plant is sensitive to powdery mildew.

Water

Water garden phlox plants weekly for the first few weeks and then often enough to keep the soil lightly moist thereafter. Garden phlox respond well to consistent irrigation. Experienced growers suggest watering at a rate of 1 in (2.5 cm. per week through summer.

Though routine watering is essential during periods of drought or especially warm weather. Keep the foliage as dry as possible by applying the water to the soil rather than the foliage.

Spread a 2 to 3-inch (5 to 7.5 cm) layer of mulch around the plants to help the soil hold moisture.

Fertilizer

Fertilize phlox with a shovelful of compost for each plant or a light application of 10-10-10 fertilizer at planting time, and again just before the flowers open. Experts suggest the use of a well-balanced, slow-release feed in spring, like this Espoma organic fertilizer from Ace Hardware. Feeding at this time will aid in the growth of foliage as well as the production of flowers.

Routine feeding can extend beyond bloom. If you fertilize once more after the flowers fade, you may get another flush of flowers. Fertilizing later will also help plants establish a strong root system in preparation for winter.

Soil & Compost

Garden phlox will grow best when planted into neutral or slightly acidic soils. Nutrient-rich beds should drain well, allowing water to move freely. The use of a high-quality compost and other amendments at planting time can further help to improve drainage and the overall soil composition of garden beds. Work some homemade compost into the soil before planting.

Propagation

Garden phlox can be propagated in a number of ways. If you are interested in how to grow phlox from seed, the process is relatively simple. You can find tons of beautiful varieties of phlox seeds from Eden Brothers or grow seeds you collected from your own plants. Though plants from your own seeds may not grow true. Since garden phlox plants are generally hybrids, the seedlings that result from dropped seeds won't resemble the parent plants.

Start seeds in early spring, sowing them into indoor trays approximately 6-8 weeks before the last predicted frost date. As the seed will require darkness to germinate, each should be covered well. Warm conditions and consistent moisture will aid in germination, occurring within one week of planting.

Garden phlox are also commonly propagated by cuttings or division. Stem cuttings can be taken in spring, with the removal of several short segments. Once prepared, the cuttings are placed into a moist medium. Rooting plant cuttings should be prompt, taking place in as little as 1-2 weeks.

Divide phlox plants in spring, just before growth resumes for the season. At this time, clumps are lifted from the soil and separated. Divisions are replanted directly, or may be potted into their own individual containers.

Pruning

Proper care of your plants also includes deadheading phlox plants after the flowers fade. This keeps the plants looking tidy and also prevents the flowers from dropping seeds and spreading.

Further trimming will not be required until fall, when the plant has died back as the result of frost. It is at this time you can cut plants back to the ground, with making certain to remove all dead or decaying plant matter from beds.

Many people wonder how to grow tall garden phlox and pruning can help with this as well. To get the maximum height from tall garden phlox, clip the weakest stems from the plant when they are about 6 inches (15 cm) tall, leaving only five or six stems on the plant. Pinch out the tips of the remaining stems to encourage a tall, bushy growth habit.

Problems, Pests & Diseases

Garden phlox are especially susceptible to common fungal diseases. Rot and powdery mildew is a concern where growing conditions are less than ideal. Good drainage and air circulation among plants will be key in their prevention.

Give the plants plenty of room, especially in hot, humid areas where air circulation around the plant will help keep powdery mildew to a minimum. Use the recommended spacing on the plant tag, which is usually 18 to 24 inches (46 to 61 cm).

Pests like mites and aphids may also frequent the plant, feeding on the sap of tender foliage.

Where to Grow Garden Phlox

Tall varieties of phlox are well-suited to the landscape. Plants will be most at-home when used in perennial flower beds and mixed borders. Large plantings are especially attractive, offering growers impressive swaths of seasonal color.

Blooming in abundance, flowers are favored by gardeners hoping to attract pollinators, as well as cut flower growers. Smaller cultivars also thrive when grown in containers, making them an excellent addition to porches and patios.

Varieties

• 'Jeana' has sweetly scented lavender-pink blooms that hummingbirds and butterflies adore. Get 'Jeana' in the Gardening Know How Shop.
• ‘Bright Eyes’ is known for its highly attractive blooms. Large flowers open in shades of pink with dark centers. Tall plants make for exceptional cut flowers, serving as a focal piece within mixed beds.
• ‘David' phlox plants will produce an abundance of pristine white florets, arranged across large heads. Plants are a welcomed addition to the mid-summer garden, blooming when little else is in-bud.
• ‘Laura’ is yet another traditional garden variety, ‘Laura’ phlox are beloved for their vibrant purple tones. Ideal for use in perennial borders, the variety is equally at-home when used in pots and containers.

Frequently Asked Questions

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