When Is The Best Time To Divide Phlox In Your Garden?

Garden phlox (Phlox paniculata), with its alluring blooms, is a popular choice among gardeners seeking to add vibrancy and fragrance to their outdoor spaces. But as these herbaceous beauties mature, they tend to outgrow their allotted spaces, which results in them competing with other plants for nutrients and resources. Moreover, such overpopulated garden beds run the risk of developing diseases, further necessitating division. While dividing phlox in your garden can be a rejuvenating exercise for your perennial, timing it right is essential to promote healthier growth and blooming.

Generally, phlox can be divided either in the spring or the fall, with some believing fall to be the better alternative as the plant has finished blooming for the season. Such propagation must be carried out every two to four years if the phlox exhibits strong growth. Remember, the division by roots method must include at least three to five shoots with their roots intact to ensure successful transplantation and long-term vitality.

The right time to divide phlox

It isn't uncommon for perennial plants, such as phlox, to show several tell-tale signs when dividing them. Some of the common symptoms include the plant beginning to bear fewer blooms or exhibiting sparse foliage. Alternatively, some phlox plants may begin growing in a circle with a bald middle patch. Perennial plants requiring staking to keep their stems together can also be a signal for division. However, waiting until your phlox starts failing may not be the right choice. Instead, it is ideal to start dividing the moment the diameter of your plant's diameter equals its height unless the phlox has already started overcrowding.

To successfully propagate phlox, target dividing the plant during the fall after it has bloomed completely. Alternatively, phlox can also be divided in the spring before it grows new shoots. Moreover, it's best to divide phlox when the temperature is cooler, as the stressed plant can dry up during sunny days because of heat. You must split the plant at least four to six weeks before the season's first frost.

How to divide phlox

The process of dividing and replanting phlox varies slightly across the spring and fall seasons. But no matter which season you start, all division processes must be preceded by deeply watering the phlox plant at least 24 hours before the split.

During early spring, start by digging up the phlox in its entirety and then cutting it with a sharp knife into multiple sections. Each section must hold its share of the root system, paired with two or three shoots. These clumps should be replanted immediately by spacing them at least 6 inches apart to allow proper aeration.

The early fall phlox division will follow a similar pattern, with the only difference occurring during the replanting stage. The divided plant sections will require a mulch layer of 4 to 6 inches of pine needles and straw to prevent the soil from freezing and inhibiting the phlox's new growth. You can later remove this layer once the spring season sets in.