The garden mum (Chrysanthemum spp.) is a popular member of the daisy family that typically blooms in late summer and autumn. Appearance varies wildly depending on the variety, although the plants are characterized by dark green, aromatic leaves that are deeply lobed. Mums require a location in the garden that receives sun for at least part of the day.
A native of Japan and Asia, mums may be grown in the home garden in U.S. Department of Agriculture hardiness zones 5 to 9. They are tolerant of mild frosts. Mums do best when grown in a sunny location in the garden, ideally one that offers direct sunlight for the majority of the day. Mums grown in partial shade have weaker stems; produce leggier, taller growth; and bloom later in the season than plants grown in all-day sun.
Mums may be planted in the spring or the fall, although plants grown in the fall are more likely to succumb to frost damage than those that have had time to establish strong root systems. Enhance the soil before planting, mixing in organic matter such as compost or peat moss. Space plants between 18 and 24 inches apart. Do not plant mums near a streetlight or other light that operates at night, as this may disrupt flower production.
Garden chrysanthemums are tolerant of a range of soil types as long as soil is well draining. A slightly acidic, moist soil enhanced with plenty of organic matter is ideal. Water regularly to encourage healthy flower growth, especially as new buds are forming. Fertilize mums that have been planted in the spring with a water-soluble plant food. Fertilizing these mums once a month helps promote flowering throughout the growing season, even in beds that do not receive full sun.
Mums grown with insufficient sunlight are more likely to attract damaging fungal diseases and may fail to flower. Plants that are not watered and fertilized regularly, or are losing nutrients to competitive weeds, may also fail to flower. Prevent weeds by applying a thin organic mulch such as grass clippings or shredded leaves across the soil. Space plants widely enough to allow proper air circulation, which dries out trapped moisture that can attract disease.