Potted perennial plants face harsher winter conditions than those planted in the ground. Without proper care, their roots can be damaged or even killed. However, with a few simple steps, you can protect your potted perennials and enjoy them again in the spring.
The roots of most plants are less tolerant of cold than their stems and leaves. In the ground, soil acts as insulation, protecting roots from freezing temperatures. In contrast, the limited amount of growing media in pots cools down much faster, exposing roots to severe cold.
To increase the chances of overwintering success, select plants that can tolerate two hardiness zones colder than your region. For instance, if you live in zone 5, choose plants hardy to zones 3 or 4 for overwintering outdoors.
Tips for Overwintering Potted Perennials
- Prepare Plants and Pots
Before winter sets in, ensure the plants are well-watered and check them periodically. Evergreens, in particular, need sufficient moisture to prevent winter burn. Even after the plant’s visible growth becomes dormant, its roots will continue to absorb water. Keeping the growing media moist also slows the freezing process, offering added protection.
- Store Indoors
Move pots to sheltered areas like an unheated garage, shed, or cool basement. Maintain temperatures between 20°F and 45°F to allow plants to experience the cold dormancy needed for healthy growth and blooming.
- Sink Pots Into the Ground
Place pots directly into the ground and cover them with mulch. The surrounding soil provides insulation, protecting roots from extreme cold and temperature fluctuations. Once the frost risk passes, remove the pots and reposition them.
- Cluster and Mulch
If sinking pots isn’t possible, group them in a sheltered spot away from wind and direct sunlight. Cover the cluster with mulch made from straw, leaves, or wood chips for added insulation.
With these methods, your potted perennials can survive winter and thrive in the coming season.