Colorful and versatile, phlox is a lovely perennial that looks great anywhere you use it. It’s equally great in the cutting garden as it is in the front of the border. Bringing vibrancy to gardens in spring and summer, the sweet-smelling blossoms are perfectly charming. 

There are several types of phlox. The creeping varieties are a lovely ground cover in low-traffic areas. The taller varieties are wonderful for floral arranging. They come in a wide range of colors, and pollinators are always happy to see them. 

In general, most types of phlox are late spring and early summer bloomers. This is always the case for creeping types. However, with the proper care, some varieties, especially the taller ones, can rebloom in the fall. With their low-maintenance nature, it’s actually quite simple. 

Phlox prefer plenty of sunlight to do their best blooming. To keep those plants healthy and robust, they like fertile, well-drained soil and the right amount of nutrients. If you want to coax your phlox to bloom again in the fall, there are some surefire ways to create the ideal circumstances.

Cherry Caramel Phlox Seeds

The Premium Seed Starting Kit

The Premium Seed Starting Kit

Grandiflora Starry Eyes Blend Phlox

Grandiflora Starry Eyes Blend Phlox Seeds

Step 1: Deadhead Right Away

Cutting spent stems redirects energy toward abundant side shoots.

Deadheading is an important habit to get into if you want your phlox to bloom again. As with all plants, phlox puts a lot of energy into its ample flowers. Once pollinated, the flowers begin to fade, and the plant puts energy into producing seeds. 

If you want to collect seeds, it’s fine to let this happen. However, setting seeds also demands significant energy from the plant. If you remove the spent flowers, the plant can then divert its energy to forming new ones!

When it comes to phlox, similar to snapdragons, a stem you cut will not grow back and flower again. Rather, the stem will begin to produce side shoots. These side shoots will each form flowers at the top. 

The result is that they don’t simply bloom again. They produce more flowers than they did the first time. Now, this next flush may produce smaller flower clusters, but they will be abundant. If you continue to remove the spent flowers, you will continue to redirect energy into new ones. 

In addition to making your phlox bloom again, deadheading serves another important function. Removing the spent flowers will make your beds appear neater and more orderly in general. 

Step 2: Fertilize 

Feeding after blooms encourages the next round of flowers.

Fertilizing after the first flush of blooms is another step towards getting your phlox to bloom again. Once you’ve deadheaded the spent flowers, a light application of fertilizer will give the side shoots a boost. These small branches will become the next round of flowering stems. 

You can choose a balanced fertilizer (a 10-10-10 formula will work for general feeding). However, if flowers are your focus, look for a bloom-boosting formula. This is typically going to have more phosphorus compared to nitrogen and potassium. Look for a formula with a larger third number, like a 5-5-10.

Only give a light application this time of year. You don’t want to push a ton of leafy growth. Use about half the amount you would usually use, or that the instructions call for. Water in your fertilizer well. If you want to give an extra boost and improve soil structure while you’re at it, add some compost on top. 

Step 3: Water Consistently

Weekly watering prevents weak, spindly growth problems.

Consistent watering is as important as the other steps for making your phlox bloom again. These perennials need consistent soil moisture to produce flowers. A lack thereof will result in weak, spindly side shoots. If your phlox dries out, it may stop blooming from the stress or produce smaller, weaker flower heads.

The ideal amount of water for these plants is about one inch per week. You may get this amount in regular rainfall, in which case you don’t need to supplement. Any time there is a stretch of several days with no rain, it’s a good idea to give them a decent soaking. 

Be sure to water at the ground level. Overhead watering deposits moisture on the leaves, and that leads to powdery mildew. Water in the morning so that the surface of the soil and the foliage have time to dry before night.

Step 4: Maintain Ventilation

Crowded foliage invites disease and weakens flower production.

Proper ventilation is also important if you want your phlox to bloom again. When airflow is poor, phlox is more susceptible to powdery mildew. This fungal disease coats the leaves in a white mold, and it weakens the plant. 

Different types of fungus can interfere with photosynthesis, leaving your plants weak and sickly. A diseased plant will put its energy into survival. Remember that plants need energy to produce flowers again. If it’s pumping a ton of energy into survival, there won’t be as much left for blooming. 

To maintain proper ventilation, make sure to space your plants properly. Plant them about 18-24 inches apart, so they have room to spread out. Around midsummer, thin out the foliage by removing any weak or spindly stems. This will allow more air to circulate between the plants. 

Step 5: Prune Lightly

Remove one-third of the old stems after blooming.

One of the best ways to encourage your phlox to bloom again is with a light pruning. Deadheading isn’t always enough to make your plants redirect enough of their energy into forming new stems. Trimming them back a bit farther will do the trick.