Hardy mum flowers, also known as garden mums or hardy chrysanthemums, are genetically capable of surviving the winter, as opposed to non-hardy mums. However, they can still die if they aren't given the proper care, maintenance and winter preparations. Healthy mums will bloom in early through late fall, usually August through mid-November. Hardy mum flowers in colors of white, yellow, orange, bronze, pink and red are common in fall gardens throughout the country.
Plant hardy mums in spring, in a sunny well-drained area of the garden. Use a garden tiller to mix organic compost into the first six inches of the soil before planting. Plant container mums at the same depth they were previously growing, and rooted cuttings so the roots are just covered with soil. Space mum plants 18 to 24 inches apart to allow room for root growth.
Add a four-inch layer of heavy bark mulch to the soil around hardy mum plants. Replenish the mulch each year in the fall for the first two years to protect the roots from harsh winter temperatures. After this, the plants should be established enough to survive winter without the added protection, although continued mulching can prevent weeds and retain moisture.
Water hardy mum flowers immediately after planting, and then twice per week during spring, summer and fall, soaking the soil to a depth of one inch. They will tolerate light drought conditions, but will perform better when regular watering is provided.
Fertilize hardy mums once per month during spring and summer using a complete water-soluble 20-20-20 NPK fertilizer. Follow the instructions on the packaging for proper dosage and application. Water immediately after application to prevent wilting or root burn, and to distribute the nutrients throughout the soil.
Pinch hardy mums to remove the growing tips, once when the plant is about six inches tall and again when the shoots have grown an additional six inches. Pinch off the growing tip of each shoot with your fingers, which will promote branching and compact growth habits, and lead to more blooms in the fall.