It will help your plants come back stronger in spring. · in the fall , after the growing season concludes, cutting back phlox is primarily done for tidiness and disease prevention. Powdery mildew thrives in the cooler, wet weather that comes along during the fall. When it comes to the best time to trim, you should cut back your phlox in the fall or early spring. Cutting back tall garden phlox in summer is generally not advised, as this can disrupt their blooming cycle. This is when the plant is beginning to go dormant, and pruning it can help stimulate new growth in the spring. · the timing of pruning depends on the type of phlox you are growing, but in general, the best time to cut back phlox is in late summer or early fall. Phlox are susceptible to powdery mildew, which is capable of overwintering and releasing spores come spring. · it is definitely recommended to cut back phlox after the end of their flowering season to benefit the health of the plant. · to prune tall phlox in fall , wait until a killing frost turns your plants brown, and then cut your plants off at the soil line. Cutting back in the fall encourages new growth and allows your plants to focus energy on their root system during the winter months. Phlox typically flowers in mid to late summer, and pruning them during this time can delay or diminish flower production. It’s best to cut back border phlox in the fall due to the plants being very susceptible to powdery mildew. This is critical if you want to keep mildew from spreading; After a killing frost turns the plants brown, tall phlox can be cut back to the ground or a few inches above the soil line.
