Chrysanthemums, often called Mums, are a highly popular perennial flowering plant whose vibrant, dense blooms symbolize the autumn season. These members of the Asteraceae family are short-day plants, meaning they naturally flower when daylight hours decrease in late summer and fall. Successfully cultivating these plants requires a deliberate, year-round approach to ensure they develop the robust structure and energy reserves necessary for a long display of color and return with greater vigor each subsequent season.
Essential Location and Soil Needs
A proper planting location is the foundation for a healthy chrysanthemum, as they require a minimum of six hours of direct sun daily to thrive. Plants grown in insufficient light will become weak, spindly, and produce fewer flowers. Mums are photoperiodic, meaning the length of darkness determines their bloom time, so position them away from bright streetlights or porch lights to prevent confusing their natural flowering cycle.
The soil composition must promote excellent drainage, as chrysanthemums are highly susceptible to root rot in waterlogged conditions. Amending the planting area with organic matter, such as compost or peat moss, improves the soil’s structure and fertility, allowing it to retain moisture while letting excess water escape. When planting, ensure that individual plants are spaced approximately 18 to 36 inches apart. This adequate spacing provides the air circulation necessary to prevent common foliar diseases.
Seasonal Watering and Feeding Regimens
Consistent moisture is necessary for chrysanthemums to produce a continuous supply of flowers. It is best to water deeply and infrequently, aiming to saturate the soil about six inches down to encourage strong, deep root systems. Always direct the water at the base of the plant and avoid wetting the foliage, as moisture on the leaves creates an environment where fungal diseases like powdery mildew can establish.
Check the soil moisture by sticking a finger an inch deep; if the top inch feels dry, it is time to water again. Adjust the frequency based on weather and whether the plant is in the ground or a container. Fertilization should begin in the spring as soon as new growth appears and continue through mid-summer to fuel vegetative growth. During this early period, a balanced fertilizer, such as a 20-20-20 NPK ratio, applied every three to four weeks supports strong stem and leaf development.
Once flower buds begin to form, typically in July, cease the application of nitrogen-heavy fertilizer to shift the plant’s energy toward bloom production rather than leaf growth. Some growers switch to a high-potassium formula to enhance the color and strength of the developing flowers. Stopping all feeding by late summer is important because encouraging new, tender growth late in the season interferes with the plant’s natural preparation for dormancy.
Shaping Blooms Through Pinching and Pruning
To achieve the dense, mounded shape and prolific flowering display, the technique known as pinching is required during the growing season. Pinching is the removal of the top half-inch to one inch of the new stem growth, typically done just above a leaf node. This process interrupts the plant’s apical dominance, forcing the development of lateral shoots instead of growing tall and straight.
Start this shaping process when the plant reaches a height of six to eight inches in the spring, and repeat the pinch whenever the new shoots have grown another six inches. The repeated removal of the growing tip causes the plant to become significantly bushier, dramatically increasing the number of potential flowering stems. This practice must be stopped around the 4th of July in most regions to allow sufficient time for the remaining stems to set buds and develop into mature flowers before the autumn bloom.
Pinching serves the purpose of shaping and increasing flower count, distinct from the final cutback. Any pruning after mid-summer risks removing the developing flower buds, which would significantly delay or eliminate the fall floral display. The plant should be allowed to grow unhindered from July onward, focusing all its energy on the final display.
Winterizing for Perennial Survival
Protecting the plant’s crown and shallow root system during the dormant period is necessary for perennial survival, especially in colder climates. After the first hard frost kills the foliage, resist the urge to immediately cut the stems down. Leaving the dead top growth intact acts as a natural layer of insulation, protecting the crown from freeze-thaw cycles.
In late fall, once the ground has frozen, apply a thick layer of loose, organic mulch, such as straw, pine needles, or shredded leaves, around the base of the plant. This mulch insulates the root zone, preventing the soil from repeatedly freezing and thawing, which can heave the plant out of the ground. The old, dead stems should only be cut back to a few inches in the early spring, just as new green shoots begin to emerge.
For container-grown chrysanthemums, overwintering requires moving the pot to a cool, dark, and frost-free location, such as an unheated garage or basement. The temperature should remain consistently between 32 and 50 degrees Fahrenheit throughout the winter to maintain dormancy. During this time, water sparingly, only enough to prevent the soil from becoming completely dry, as the plant is not actively growing.