Mums (Dendranthema x grandiflora) need regular watering to provide an evenly moist soil during the growing season, but they need little or no water when dormant. Also called garden mums and chrysanthemums, mums are perennial plants that are often grown as annuals. They are hardy in U.S. Department of Agriculture plant hardiness zones 8 through 10a, and grow 1 to 2 feet tall and wide. Flowers colors include red, red-orange, yellow, pink, white and brown.
Mums can suffer from fungal diseases on their foliage. Water mums in the morning to allow wet leaves to dry by evening, and apply the water at the base of the plants.
Newly Planted Mums
Newly planted mums need frequent watering to grow quickly and become established. Water newly planted mums when the soil surface is dry to the touch, and apply enough water to moisten the soil to the depth of the mums' root balls. Don't water so much that the soil becomes soggy.
Mums that experience drought in the early stages of growth begin flowering too early, which reduces blooming later.
Established mums can tolerate some drought but perform best in evenly moist soil. The amount of water the plants need and how often they need it depends on the soil type and the weather. Mums growing in sandy soil may need water every day during hot, windy weather, but mums growing in clay soil might not need any water when there is rain every three or four days.
Signs of overwatered mums include yellow leaves that blacken over time and drop. Underwatered mums lose their lower leaves, and the stems grow tough and woody.
Water established mums when the soil is dry to a depth of 1 to 2 inches. Apply enough water to moisten the soil to the depth of the plants' root balls.
Container mums may need water every day. Water mums in containers when the potting soil surface is dry. You can quickly check whether potted mums need water by picking up the container. If the container feels heavy, the plant probably does not need water, but a light container needs a closer look.
Containers for growing mums must have drainage holes. Overwatered container mums develop root rots. Don't allow container mums to sit in water.
Pour water over the potting soil surface until it flows through the drainage holes. Wait until the water no longer drips from the holes before replacing the mums on the drip trays.
Dormant mums have stopped growing and so need very little water. When flowering is over, mums stop growing and become dormant. In cold zones the plants die down. Watering plants that aren't growing can drown their roots. Check dormant mums every one or two weeks, and water them only when the ground or potting soil is dry to a depth of 2 inches. When new shoots appear in spring, start up a regular watering schedule again.