The best known of all phlox, the garden phlox, can be easily propagated by division with just a few strokes of the spade and kept healthy at the same time.
In late autumn, at the time of pause in vegetation, is the best time to propagate a phlox by division and thus rejuvenate the perennial at the same time. During its dormant period, the phlox copes particularly well with this measure, and in November the soil is usually not yet frozen. Otherwise, depending on the weather, you may have to wait until spring to divide until the ground has thawed again.
How to propagate phlox by division
Cut off the dead shoots about a hand width above the ground. This not only makes it easier to dig up and divide the plant afterwards, but is a recommended care measure for phlox (Phlox paniculata) after flowering anyway. Use the spade to dig into the soil around the shoots. Gently move the spade back and forth until you feel that the root ball is gradually coming out of the soil more easily. Lift the perennial with the spade. When the entire root ball can be removed from the soil, the perennial is ready for dividing.
Dividing is particularly easy with a narrow spade blade. Cut the rootstock in half first by piercing between the shoots and severing the root ball with a few strong strokes of the spade. Apply the spade a second time and cut the root ball in half across the two halves another time. The resulting quarters are large enough to sprout vigorously next year. If your plant is smaller, maybe only one division is necessary.
All sections are moved to their respective new places. Choose sunny locations with nutrient-rich soil. To prevent mildew or stem nematode infestation, do not plant phlox in the original growing location for the next six years. However, if a section is to remain there, replace the soil as a precaution. Choose the planting hole in the new location so that the phlox is not crowded by neighboring plants and the leaves can dry out well. Mix a little compost into the excavated soil and water the young plant well.