Coral Bells (Heuchera) are herbaceous perennials known for their colorful foliage. Their root structures survive the winter months to regrow foliage in the spring. These plants are native to North America and are valued in gardens for their wide array of leaf colors, which range from lime green and amber to deep purple and nearly black. Their perennial nature makes them a reliable choice for adding interest to the garden.
What Makes Coral Bells Perennial
The ability of Heuchera to return annually is rooted in its biological structure. Unlike annuals, Coral Bells maintain a woody rootstock or crown at the base of the plant that remains alive beneath the soil surface, even if the foliage dies back in cold weather. This crown is the central point from which all new growth emerges each spring, allowing the plant to survive dormancy.
Coral Bells are generally hardy across USDA Hardiness Zones 4 through 9. This tolerance for cold temperatures is a hallmark of successful perennials. The plant enters a dormant state when temperatures drop, relying on stored energy in its crown to withstand the winter chill. It may remain evergreen in milder climates, while in colder zones, it acts as a semi-evergreen or deciduous perennial.
Protecting the Plant During Winter
A primary threat to the survival of Coral Bells during winter is poor soil conditions, not the cold itself. The plants require well-drained soil, as excessive moisture around the crown can lead to root rot, a common cause of plant loss. Amending heavy clay soil with compost or organic material before planting helps ensure proper drainage around the shallow root system.
Another danger is frost heaving, which occurs when repeated cycles of freezing and thawing push the plant’s shallow crown out of the soil. This displacement exposes the roots to drying winds and cold. Applying a protective layer of light, loose mulch, such as pine straw or shredded leaves, after the ground has frozen helps insulate the soil and stabilize its temperature. Avoid burying the crown itself under a thick layer of mulch, which can trap moisture and promote rot.
Renewing Older Plants
While Coral Bells are perennials, they are considered short-lived, often losing vigor after three to five years. This decline is due to “crown buildup,” where the woody rootstock elongates and begins to rise above the soil line. As the crown lifts, it becomes vulnerable to drying out during the summer and damage from winter heaving.
To maintain plant health, gardeners should rejuvenate the plants through division every few years. The best time for this renewal is typically in early spring or early fall, allowing new roots to establish before temperature extremes. The process involves digging up the clump, cutting away the woody center, and replanting the younger, outer sections of the crown. When replanting, the new crown should be set just at or slightly above the soil surface to prevent moisture accumulation and rot.