Start with a very clean vase. Fill it about halfway with fresh, cool water; add the included cut-flower food to the vase. Hold each stem next to your vase to gauge how much you'll need to trim. Remove any foliage (leaves) that will fall below the waterline; submerged foliage can rot and encourage bacteria that shorten bloom life. Fill a sink with cool water. Using a sharp knife or floral shears, cut stems underwater at a 45-degree angle. This prevents them from sitting flat in the vase and allows for better water absorption. Arrange the flowers in the vase.
Chrysanthemums' foliage deteriorates more quickly than the flowers themselves. Remove the foliage as soon as it begins to droop. Chrysanthemums are susceptible to stem blockage, so recondition them daily: Cut the stems, change the water, and add nourishment. Use the extra pack of cut-flower food with your first change of water. Later, use a solution of one teaspoon sugar and two drops liquid bleach per gallon of water. Keep your flowers in a cool room, away from sources of heat and drafts. Chrysanthemums release a relatively high amount of ethylene, a natural gas emitted by plants. This is damaging to other flowers, so chrysanthemums are best kept to themselves in arrangements.