Plant chrysanthemums in the spring to ensure the flowers develop a strong root system before winter, and allow potted mums that are purchased in the fall to remain in their containers until spring. Plant mums in a location with at least three hours of direct sun daily. Mums thrive in slightly acidic, well-worked soil that contains organic matter. Use a combination of standard fertilizer and super phosphate, and prune the plants regularly throughout the growing season to encourage ample blooms.
After planting mums in the spring, water the flowers to a depth of 1 inch per week, and water the flowers more frequently as temperatures increase over summer. To produce short, bushy mums, prune the top 1 inch off the plant in the spring when it reaches 6 inches in height. Continue pruning the top 1 inch of the plant for every 6 inches of growth until the beginning of August.
After the first frost, cut the plant back to ground level, and cover it with a thick layer of mulch. Rake the mulch back in the spring after the danger of frost has passed.
Store mums that are purchased in the autumn in their containers in a protected location that is cool and dry. After the first frost of the season, cut the foliage off to soil level. Mist the roots lightly throughout winter, and do not allow them to freeze. Plant the flowers in the garden the following spring.