Sedum, commonly known as stonecrop, is a perennial succulent celebrated for its ability to thrive in poor soils and tolerate drought. Whether this resilient plant dies back in winter depends on its specific growth habit, as the genus includes hundreds of species with differing survival strategies. Understanding the distinction between the two primary types of stonecrop is key to knowing what to expect during the cold months.
Distinguishing Between Sedum Varieties
The majority of garden Sedums fall into two categories: upright and creeping, and their visible winter behavior is dramatically different. Herbaceous, upright varieties, such as the popular ‘Autumn Joy’ or Hylotelephium spectabile, appear to die back completely above ground. These taller stonecrops develop brown, dried flower heads and stems after the first hard frost. The dried stalks and spent flowers often provide structure and texture to the winter landscape, a feature many gardeners choose to preserve.
Conversely, the evergreen, creeping varieties, which include plants like Sedum acre or ‘Angelina,’ maintain their foliage throughout the winter. These low-growing stonecrops form dense mats across the soil, typically only growing a few inches tall. While the leaves remain on the plant, their color often deepens, shifting to shades of bronze, red, or orange in response to cold temperatures and reduced light. This color change is a visible sign of the plant’s physiological adjustment.
The Biology of Winter Dormancy
The dieback observed in upright Sedums is a deliberate biological process known as dormancy, not actual death of the plant. As temperatures fall and daylight hours shorten, the plant receives environmental cues to begin cold acclimation. This involves drawing nutrients and energy reserves from the above-ground stems and leaves down into the crown and the root system for storage.
This translocation of energy ensures the survival of the plant’s living core, which is the root ball and the apical meristem just beneath the soil surface. To prevent internal freezing, the plant actively adjusts the chemical composition within its cells. This process includes reducing the water content in tissues and increasing the concentration of dissolved sugars and proteins, which collectively act as a natural antifreeze. The plant crown and roots are generally hardy and protected by a layer of soil, effectively waiting out the winter until warmer temperatures trigger new growth in the spring.
Preparing Sedum for Cold Weather
Taking a few simple steps in the fall can help support the Sedum’s natural process of hardening off for the winter. Reducing the frequency of watering in late autumn is beneficial, as it encourages the plant to dry slightly, which aids in the necessary reduction of water content within its cells for cold hardiness. Excess moisture around the crown during the winter can lead to rot.
The timing of pruning for the upright varieties is a common point of discussion among gardeners. Some prefer to cut the dead stalks down to the ground after the first hard frost in late fall to prevent pests from overwintering in the debris. However, many choose to leave the spent flower heads standing throughout the winter because they offer visual interest and provide a food source for birds, delaying the cutback until early spring just before new growth emerges. For newly planted or borderline-hardy varieties, a light layer of mulch can provide additional thermal insulation for the root zone. Snowfall can also act as an excellent natural insulator, protecting the plant crown from extreme temperature fluctuations.