Potted Florist Mums
Potted florist mums typically hit the market in late summer or early fall already in full bloom and ready for display. These mums have been forced into bloom and do not require fertilizer to keep them looking good. Florist mums are typically discarded after they finish blooming.
Mums Planted in the Spring
Mums planted in the spring need a good fertilizer routine to promote healthy growth and blooming in late summer or early fall. Granular fertilizer, such as 15-10-10 applied at a rate of 2 to 3 pounds per 100 square feet, give your mums a good start when incorporated into the soil before planting. Beginning approximately two weeks after planting, water-soluble fertilizer with a formula of 15-30-15, mixed to a rate of 1 tablespoon per gallon of water, can be applied every seven to 14 days until the buds set and your mums begin to bloom.
Mums in the Perennial Bed
Perennial mums die back to the roots in the fall and produce new growth in the spring. Like other perennials, mums benefit from an application of fertilizer in early spring when new growth appears. Water-soluble fertilizer 15-10-10 applied at a rate of 1 tablespoon per gallon of water every seven to 14 days until the perennial mums begin to set buds and bloom keeps them healthy and promotes abundant blooming.
Garden mums are known to be unreliable when it comes to recommended hardiness zones, as how well they overwinter depends on the weather and the cultural care they have received before you purchased them. Plants that have been pampered, even if labeled as hardy in your planting zone, may not overwinter well. Florist mums are best discarded after blooming, as they seldom overwinter well. However, if you enjoy a challenge, go ahead and plant mums purchased in pots in the fall. Allow at least six weeks before the first frost so the plants can develop a strong root system and you may be rewarded with new growth in the spring.