Mammoth Mums are a type of chrysanthemum known for their large size, robust growth, and hardiness. Unlike many garden mums treated as annuals, these plants are reliable perennials, returning year after year with appropriate care. Mammoth Mums can grow into shrub-like forms, reaching 2 to 3 feet tall with a spread of 4 to 5 feet within three years. They offer abundant blooms, providing a vibrant display in late summer and fall. Their resilience and impressive size make them a rewarding addition to many gardens.
Growing Mammoth Mums
Successful growth of Mammoth Mums begins with careful site selection and proper soil preparation for robust growth. These plants thrive in full sun, receiving at least six hours of direct sunlight daily, though they can tolerate partial shade. Good air circulation is also important for their health.
Mums prefer well-draining soil rich in organic matter. A slightly acidic pH, between 5.8 and 6.8, is optimal for their growth. If your soil is heavy clay, incorporating compost or perlite can improve drainage and fertility.
Planting Mammoth Mums in the spring is recommended to allow root establishment before winter. When planting, ensure proper spacing. Plant them at the same depth they were in their nursery pot, ensuring the root ball integrates with the surrounding soil.
Mammoth Mums require consistent moisture, especially during dry spells, but avoid waterlogging. Water deeply and regularly, particularly after planting, to encourage strong root development. Wilting can inhibit growth, so avoid prolonged dry periods.
Fertilizing supports healthy growth and abundant blooms. A balanced NPK fertilizer can be applied in early spring when new growth emerges. Continue monthly applications until mid-July or bud formation. Switching to a lower nitrogen fertilizer as blooming approaches encourages flower production over leafy growth.
Unlike many other chrysanthemum varieties, Mammoth Mums are specifically bred to form a dense, mounded shape and produce abundant blooms without extensive pinching. While traditional mums often require pinching back stems to encourage bushier growth and more flowers, Mammoth Mums do not require this step. This simplifies their care, allowing them to grow naturally.
Mammoth Mums are relatively trouble-free, but can encounter pests and diseases. Common issues include aphids and spider mites, managed with insecticidal soaps or other treatments. Fungal diseases like powdery mildew, rust, and leaf spot may occur, especially in humid conditions or with poor air circulation. Good air flow and avoiding overhead watering help prevent these issues.
Ensuring Perennial Return
Specific care during the dormant season ensures Mammoth Mums return year after year. In late fall, after the first hard frost, allow the foliage to die back naturally. Do not cut back foliage immediately after blooming, as stems provide insulation for the plant’s crown during winter.
After the ground freezes, apply a protective layer of mulch, about 3 to 4 inches deep, around the base of the plants. Straw or shredded hardwood are suitable mulching materials to insulate roots from extreme cold and prevent frost heave. This protective layer is especially beneficial in colder climates or areas with inconsistent snow cover.
In early spring, gradually remove the winter mulch. This allows new shoots to emerge and prevents rot from trapped moisture. Clear away any old, dead debris from the previous season. Once new growth is visible and the threat of severe frost has passed, prune any remaining dead stems to just above ground level.
Troubleshooting Common Issues
If mums produce few or no blooms, several factors could be at play. Insufficient sunlight, less than six hours daily, can significantly reduce flowering. While Mammoth Mums do not need pinching, insufficient light can reduce flowering. Excessive nitrogen fertilizer also promotes leafy growth at the expense of flowers, so adjust the fertilizer ratio as blooming season approaches.
A leggy appearance in Mammoth Mums is linked to insufficient light, causing the plant to stretch in search of more sun. Although these mums are bred for a compact habit without extensive pinching, ensuring they receive full sun is important to maintain their dense shape. If a plant becomes leggy, increase light exposure for the following season.
Discolored leaves can indicate various underlying problems. Yellowing leaves suggest nutrient deficiencies, especially if fertilization is inadequate or soil pH is imbalanced. Overwatering can lead to yellowing and wilting, as roots become waterlogged and cannot absorb nutrients. Under-watering also causes leaves to wilt and turn yellow or brown. Pest infestations, such as aphids or spider mites, can also manifest as discolored or distorted foliage.