Garden mums (Chrysanthemums) are popular and recognizable flowers that provide a burst of color when most other plants fade in the fall. These hardy perennials can return to the garden year after year with proper care. Understanding their cultural needs is key to enjoying their vibrant autumn display. This guide details the steps necessary to cultivate healthy, full, and long-blooming garden mums.
Establishing Mums: Site Selection and Planting
Selecting the correct location is foundational for ensuring mums thrive and return each season. Chrysanthemums perform best in full sun, meaning at least six hours of direct sunlight daily. Insufficient light leads to weak, “leggy” growth and fewer flowers.
The soil composition is equally important, requiring a rich, well-draining environment to prevent root rot. Mums are intolerant of standing water, so amend heavy clay soil with organic matter like compost or aged manure to improve drainage and fertility. The optimal time for planting perennial mums is in the spring, giving the plant an entire growing season to establish a robust root system before winter. While fall planting is possible for immediate decoration, it provides less time for perennial establishment in colder climates. Space individual plants 18 to 24 inches apart to ensure good air circulation and prevent fungal diseases.
Routine Maintenance: Watering and Feeding
Consistent moisture is necessary for mums throughout the growing season because their shallow root systems dry out quickly. The goal is to keep the soil consistently moist but never waterlogged. Water deeply, aiming to penetrate about six inches down, which encourages the development of strong roots.
Check the top inch of soil to determine if watering is needed; if it feels dry, water. Always direct water at the base of the plant to avoid wetting the foliage, as moisture on the leaves encourages powdery mildew and leaf spot diseases. During high heat or drought, established in-ground mums may require water two to three times per week, and container mums may need daily checks.
Mums are heavy feeders and benefit from regular fertilization starting in the spring once new growth emerges. Apply a balanced, slow-release granular fertilizer early in the season for sustained nutrition. Alternatively, use a monthly application of a liquid, balanced fertilizer until mid-July. Ceasing fertilization by mid-summer is important because it allows the plant to shift energy from vegetative growth to setting flower buds for the autumn display.
Shaping and Encouraging Blooms
The process of “pinching” controls the plant’s shape and maximizes flower production. When new stems reach about six inches in height, remove the soft, tender growing tip. This breaks the plant’s hormonal dominance in the central stem, forcing the development of two new side shoots from the leaf nodes below.
Repeat pinching every two to four weeks through late spring and early summer to create a dense, multi-branched plant. This structure yields the characteristic round, mounded shape and profusion of fall blooms. The final pinch must be performed by early to mid-July, as later pinching risks removing developing flower buds. Once blooming begins, deadheading (removing spent flowers) helps maintain a tidy appearance and directs energy toward producing remaining flower buds.
Preparing Mums for Winter Survival
Successfully overwintering garden mums ensures their perennial return, especially in cold regions. After the first hard frost causes the foliage to turn brown, leave the dead stems and leaves intact. This dead growth provides an insulating layer that protects the plant crown and roots from temperature fluctuations.
Applying a thick, protective mulch is the most important winter preparation task. Once the ground has frozen solid in late fall, apply a four to six-inch layer of straw or pine needles over the plant crown. This mulch prevents the soil from repeatedly freezing and thawing, which causes frost heaving. A deep watering just before the ground freezes is also beneficial. In the spring, once the threat of severe frost has passed, cut back the old stems to allow new growth to emerge.