Mums, or chrysanthemums, are the undisputed royalty of the fall garden. Their vibrant blooms provide a crucial pop of color when most other plants are winding down for the season. However, these hardy perennials require specific care to survive the winter and return with even more vigor the following year. Understanding how to winter mums is the difference between losing these beautiful plants and enjoying a stunning display season after season.
Preparing Mums for the Cold
The journey to successful winter survival begins well before the first frost. Throughout the growing season, focus on building a strong foundation for your plants. This means regular watering, especially during dry spells, and deadheading spent blooms to encourage new growth. Feeding your mums with a balanced fertilizer in early summer provides the necessary nutrients, but stop feeding by mid-summer to prevent new, tender growth that would be vulnerable to frost damage.
Planting and Soil Considerations
Location plays a critical role in winter hardiness. Plant your mums in a spot that receives at least six hours of direct sunlight daily. Good air circulation is essential to prevent fungal diseases, so avoid cramming them into tight corners. The soil itself should be well-draining; soggy soil around the roots is a primary cause of root rot during the cold months. If your soil has poor drainage, consider creating a raised mound or incorporating organic matter like compost to improve the structure before planting.
Mulching for Insulation
The Importance of a Protective Layer
Once the ground begins to cool in late fall, apply a generous layer of mulch around the base of the plants. This layer acts as insulation, protecting the crown of the plant—the point where stems meet roots—from damaging freeze-thaw cycles. Use an organic material such as shredded bark, straw, or leaf mulch. Apply the mulch after the ground has frozen to prevent rodents from nesting in the warmth near the roots.
Watering Through the Season
Even though the days get shorter, mums still require adequate moisture to survive the winter. Before the ground freezes, give your plants a deep watering. This helps them store water and prevents dehydration caused by winter winds and sun. Avoid watering the foliage in the evening, as this can promote disease. Instead, water the soil directly during the warmer parts of winter if there is no rainfall and the ground is not frozen.
Pruning Timing
To Cut or Not to Cut
Pruning mums is a topic of debate among gardeners, but timing is key. In the fall, you should cut the stems down to about 4 to 6 inches above the ground after the first killing frost. This removes the unsightly dead growth and helps the plant conserve energy for root development rather than maintaining long, dead stems. However, avoid heavy pruning in late summer or early fall, as this can remove the flower buds you want to enjoy.
Dividing for Long-Term Health
If your mum plant has become crowded—usually evident in the center of the plant dying out—it is best to divide it. The ideal time for division is in the spring, just as new growth appears. Dig up the entire clump, separate the healthy outer sections, and replant them immediately. Dividing rejuvenates the plant, improves airflow, and prevents the center from becoming hollow, ensuring a healthier plant that can better withstand winter stress.
Regional Considerations
The specific winterizing steps can vary depending on your climate zone. In colder regions (zones 4 and 5), a thicker mulch layer or additional protection like burlap wraps around the pot may be necessary. Gardeners in milder climates (zones 7 through 9) might simply need to ensure good drainage and perhaps a light trim. Always check the specific hardiness rating of your mum variety to understand its natural tolerance to cold temperatures.
