Potted mums are usually treated as annual flowers because they cannot tolerate the cold conditions during the winter months. Most potted varieties are known as florist's mums since they are sold as a living seasonal bouquet. A different mum variety, called hardy mum, is typically grown as a bedding plant. Tender, potted mums can survive the winter months with proper care and protection from frost, providing you with a second year of flowering the following fall.
Remove the mums from the pot they came in once flowering completes. Divide the roots of the separate plants. Most purchased mums come three or more plants to a pot.
Replant the mums into 6-inch diameter pots filled with standard potting soil, planting one plant per pot. Plant the mums at the same depth they were growing at in the previous pot.
Cut back the old flower stems on each mum plant. Trim the stems after the foliage begins to die back naturally.
Bring the mums indoors once the outdoor temperature drops below 15.6 degrees C. Place the mums in a sunny window. Leave mums outdoors in areas with warm winters.
Water the mums when the top of the soil begins to feel dry. Provide enough water to moisten the soil but avoid overwatering, which can cause soggy soil conditions.
Pinch off the top inch of each shoot once the shoots are approximately 6 inches long. Pinching causes lateral branching and further flower bud formation. Continue to pinch the plants until late July.
Move the plants outdoors once nighttime temperatures are regularly above 15.6 degrees C in spring. Bring the plants indoors temporarily if a late season frost is expected.
Mums go dormant in the winter, even when kept indoors. The plants produce new growth in the spring.
Mums may not flower as well the second year, even with proper winter care.