Chrysanthemums, commonly known as mums, are perennial flowering plants belonging to the Asteraceae family. These plants are broadly categorized into two main types: garden mums, which are bred for hardiness and ability to survive cold winters, and florist mums, typically sold in pots for temporary indoor or patio display. Understanding the differences between these types and providing appropriate care ensures their longevity and maximum flowering potential, allowing enthusiasts to enjoy these resilient flowers year after year.
Caring for Newly Purchased Potted Mums
Mums purchased are frequently florist varieties, bred for immediate visual impact rather than long-term garden survival. These container plants often arrive heavily root-bound. Place the pot in bright, indirect light to maintain flower color and prolong the bloom period. Direct sunlight can rapidly dry out the soil and potentially scorch the petals.
The watering needs of these densely packed plants are often high; check soil moisture daily by inserting a finger about an inch deep. When the top inch feels dry, water slowly and deeply until water flows freely from the drainage holes. Never allow the container to sit in standing water for more than an hour, as this quickly causes root rot.
To encourage continued flowering, deadheading is recommended. Pinching or snipping off spent flower heads prevents the plant from diverting energy into seed production. Removing old blooms redirects resources toward developing unopened buds, extending the display’s life. Once the blooming cycle is complete, these florist types are typically discarded unless they are hardy garden varieties.
Site Selection and Planting for Garden Mums
For mums intended as permanent landscape features, selecting the proper site is foundational for long-term health and abundant flowering. Garden mums require a minimum of six hours of direct sunlight daily to support the energy demands of producing fall blooms. Insufficient light results in weak, leggy stems and fewer flower buds, compromising the plant’s structural integrity.
Soil composition is equally important, as chrysanthemums are highly susceptible to root rot in poorly drained conditions. Loamy soil that retains moisture without becoming saturated is ideal, maintaining a slightly acidic to neutral pH (6.0 to 7.0). Amend heavy clay soils by incorporating organic matter, such as compost or peat moss, to enhance porosity and aeration.
The optimal time for planting hardy mums is during the spring, after the last hard frost, allowing the root system an entire growing season to establish. Dig a hole slightly wider than the root ball, setting the plant at the same depth or slightly higher than it was in its nursery pot. Adequate spacing (18 to 36 inches apart) promotes air circulation, which helps prevent humidity buildup and suppresses fungal diseases later in the season.
Routine Seasonal Care and Overwintering
Once established, a consistent care regimen ensures the development of robust plants capable of heavy flowering. Established garden mums benefit from deep, infrequent watering, which encourages downward root growth and resilience to dry spells. Keep the soil consistently moist, especially during active growth and bud development, but never allowing the area around the base of the plant to become waterlogged.
Fertilization should begin early in the spring as new shoots emerge. A balanced, slow-release granular fertilizer (e.g., 10-10-10 formulation) provides necessary nutrients for foliage, root, and flower development. Cease all fertilizer applications by mid-July, as continued feeding promotes soft growth susceptible to early frost damage and reduces the plant’s natural hardening process.
The most important cultural practice for shaping a mum and maximizing its bloom density is called “pinching.” Starting in the spring when the new shoots are about six inches tall, the top half-inch of the stem should be removed using fingers or small shears. This action eliminates apical dominance, forcing the plant to produce side branches, resulting in a dense, dome-shaped habit.
This pinching process must be repeated every two to four weeks until approximately the end of June or the first week of July, depending on the cultivar’s bloom time. Stopping the pinching at this time allows the plant enough time to set flower buds for the autumn display. Mums that are not pinched often grow tall and leggy, resulting in fewer, smaller flowers and a greater tendency for the stems to flop over.
Preparing hardy garden mums for winter requires specific protection. After the plant finishes flowering and the foliage is killed by frost, the dead stems should generally be left standing. These stems help trap insulating snow and organic debris, offering natural protection to the crown.
Once the ground has frozen solid, apply a thick layer of dry, loose mulch (straw or shredded leaves) over the crown area to a depth of four to six inches. This mulch helps maintain a consistent cold temperature and prevents damaging freeze/thaw cycles that can heave the plant out of the soil. Cutting the stems back to four to six inches is typically reserved for early spring before new growth begins.
Identifying and Treating Common Problems
Mums are generally robust, but they can occasionally encounter specific pests and fungal diseases that require intervention. Small, soft-bodied insects like aphids frequently congregate on new growth and flower buds, sucking the plant’s sap and weakening the stems. Similarly, spider mites thrive in hot, dry conditions, often evidenced by fine webbing on the undersides of the leaves.
The initial treatment for both these pests involves applying a targeted stream of water to dislodge the colonies or using a horticultural oil or insecticidal soap spray. Fungal problems, such as powdery mildew, appear as a white, powdery coating on the leaves, usually resulting from high humidity and poor air circulation. Leaf spot, characterized by dark lesions on the foliage, is another common infection.
Managing these fungal issues primarily involves improving the plant’s environment by ensuring adequate spacing and avoiding overhead watering, especially late in the day. If the infection is severe, removing and destroying the visibly affected leaves can slow the spread. Applying an approved garden fungicide according to label directions may be necessary to protect the remaining healthy foliage during sustained periods of wet weather.