The two most popular types of phlox are a tall, graceful variety, Phlox paniculata, and a low spreading type, Phlox stolonifera. You can propagate either of these with little difficulty in growing zones across North America. Follow these suggestions to successfuly propagate your phlox flowers.
Phlox Paniculata (Fall Phlox)
These phlox grow up to 4 feet in height and can extend across 3 feet of garden area. Their blooms are usually pinkish-purple and will flower from late June until September. To maintain abundant mature growth and profuse blooming, divide these phlox at the rootball at 4-year intervals. Propagate by dividing flowers in the early fall while still flowering. Take care when digging up clumps of phlox paniculata to prevent dislodging other plants in the area. Plant in a spot that gets full sunshine for 6 or more hours daily. A slightly sandy soil with consistent drainage is best for fall phlox. Water when the soil dries slightly. Over-watering is harmful to Fall phlox, as it can encourage mold growth at the roots. This phlox will flower just once but hold its delicately scented blooms for several weeks between July and the end of August.
Phlox Stolonifera (Creeping Phlox)
Creeping Phlox grow up to only 6 inches above the ground surface, and spread laterally to nearly 2 feet across. Their flowers range in color from pale lavender to a strong violet in spring to early summer. An evergreen plant which grows by sending out runners, you can propagate it successfully from stem cuttings. Take cuttings 6 inches long in the early spring from a lateral shoot near the tips. Gently pull off leaves from the bottom third of the cutting. This portion will go into the ground. Creeping Phlox do well in partial shade, but ensure the soil has adequate drainage. Add sand or fine gravel if the clay content is high. Dip the stem tip in a rooting fertilizer, and plant it in the ground about 4 inches below the surface. Water sparingly so the fine root filaments will stretch out deeper to get water.
Phlox drummondii (Annual Phlox) blooms from midsummer into fall when deadheaded regularly. Some varieties grow to 18 inches in height while others are creepers. Take cuttings to propagate this phlox indoors in the early fall, just as blooming begins to slow. Propagate a few tips as the success rate for these is just average. Strip off flower buds and leaves from the stem, and treat the rooting end with a root-promoting fertilizer. Use a potting soil that has both peat and vermiculite to help with drainage and provide organic nutrients. Plant in 8-inch deep pots, halfway down in the pot. Press soil in firmly to support the stem cutting. Water with a sprayer and keep the roots from getting too wet to forestall mold growth. Keep in a sunny south or west window, until the plant has grown full-sized leaves. Plant outdoors in sandy soil with good drainage in the spring.
Phlox attract butterflies with their bright foliage and nectar, so make room for some in your garden.