Coral Bells (Heuchera species) are popular ornamental plants, prized for their colorful foliage that remains attractive throughout the growing season. While these perennials are often promoted as naturally resistant to many common garden pests due to astringent compounds, they are not immune to damage. When a healthy plant suddenly declines or the leaves become tattered, identifying the specific culprit is the first step toward recovery. Damage can originate from ground-level feeders, subterranean attackers, or larger grazing mammals, each leaving distinct signs.
Primary Invertebrate Pests
The most common and visible damage to coral bells is inflicted by surface-dwelling invertebrates, specifically slugs, snails, and the adult black vine weevil. Slugs and snails are soft-bodied mollusks that feed primarily at night or during damp weather, chewing ragged, irregular holes, often toward the center of the leaf. Their definitive indicator is the silvery, dried slime trail left behind on the leaves or surrounding soil.
Damage from the adult black vine weevil (Otiorhynchus sulcatus) is highly characteristic, appearing as small, semicircular notches neatly cut out of the leaf edges. These flightless beetles are nocturnal feeders, hiding in debris during the day. Although the leaf damage is mostly cosmetic and rarely harms the plant, its presence warns of a more serious threat lurking beneath the soil surface.
Occasional Mammalian Browsers
Coral bells are often listed as deer and rabbit resistant because their foliage contains bitter tannins. However, this resistance is not absolute, and browsing occurs when food sources are scarce or when young growth is present. Damage caused by larger mammals differs significantly from insect damage due to their dental structure.
Deer lack upper incisors, causing them to tear the foliage when they feed, resulting in ragged, unevenly broken stems and leaves. They often remove a large amount of material in a single grazing event, typically from the top of the plant or new flowering stalks. Rabbits possess sharp incisors that allow them to make clean, 45-degree angled cuts through stems close to the ground. They tend to target younger Heuchera specimens, often consuming entire shoots or leaves.
Subterranean Root and Stem Eaters
The most serious threats to coral bells are pests that attack the plant below the soil line, leading to sudden wilting or complete collapse. The larvae, or grubs, of the black vine weevil are the most devastating subterranean feeders. These creamy-white, legless grubs curl into a distinct C-shape and feed on the fine feeder roots, root crowns, and the plant’s base. If a Heuchera wilts despite adequate watering, or if the crown is easily lifted because its roots have been severed, weevil grubs are the likely cause.
Another underground pest is the cutworm, the larval stage of certain moths, which attacks young plants. These pests wrap around the stem at or just below the soil surface, chewing through it completely and causing the seedling to be cleanly severed. Voles, which are small rodents, may also contribute to root damage by tunneling and gnawing on the fleshy roots and crowns.
Identifying Damage and Implementing Control
Accurate diagnosis requires observing both the damage pattern and the timing of the injury. If you notice semicircular notches on leaf edges, inspect the soil at night with a flashlight to hand-pick adult black vine weevils and reduce egg-laying. If a plant suddenly wilts or is easily pulled from the ground, immediately investigate the root zone for the characteristic C-shaped weevil grubs. The most effective control for weevil larvae is the application of beneficial nematodes, such as Steinernema or Heterorhabditis species. These should be watered into the soil when temperatures are appropriate for nematode activity.
For slug and snail damage, look for the pests under leaves or debris during the early morning. Use iron phosphate pellets, which are safer for wildlife than traditional baits. Exclusion is the best strategy for mammalian browsers, often involving fencing or the use of taste-based repellents. Repellents containing ingredients like putrescent egg solids or capsaicin must be re-applied after rain. Maintaining good cultural practices, such as removing fallen leaves and garden debris, helps eliminate the moist hiding places that many invertebrate pests prefer.