The most common problems with heuchera are crown rot, frost heaving, powdery mildew, rust, and black vine weevils. Crown rot kills more coral bells than everything else on this list. It almost always comes from soil that stays too wet around the base of your plant. Getting ahead of these issues starts with knowing what to look for.
I've dealt with most heuchera diseases in my own garden over the past six years. The hardest part was telling the difference between crown rot and frost heave damage in spring. Both make the plant look dead, but the cause and fix are different. Crown rot shows up as a mushy, brown base with a bad smell. Frost heave pushes the whole plant out of the ground with the crown and roots sitting on top of the soil. I lost four plants one spring before I learned to check for these clues.
Crown rot comes from a water mold called Phytophthora that thrives in wet soil. NC State Extension calls it the number one killer of coral bells in home gardens. If your plants wilt even though the soil feels moist, pull one up and check the roots. Healthy roots are white and firm. Rotted roots are brown, soft, and break apart when you touch them. Once rot takes hold, you can't save that plant. Pull it out and fix the drainage before you put a new one in.
Powdery mildew and rust are the other heuchera diseases you'll run into most often. Mildew shows up as a white dusty coating on the leaves during humid weather. Rust creates small orange or brown bumps on the undersides of leaves. Both spread fast in crowded beds with poor air flow. Space your plants 14 to 18 inches apart and avoid wetting the leaves when you water. If mildew hits, a basic fungicide spray clears it up within a week or two.
The coral bells pests that cause the most damage are black vine weevils. You'll spot their work by the half-circle notches they chew into leaf edges at night. The adult beetles do some harm, but their larvae do the real damage by eating roots under the soil. I found weevil grubs in the soil around a dying coral bell two years ago. The roots were chewed down to almost nothing. Treat infested soil with beneficial nematodes in late summer to kill the larvae before they destroy your plants.
You should also watch for Japanese beetles, mealybugs, and foliar nematodes on your coral bells. Japanese beetles chew holes in the leaves during summer, and you can pick them off by hand or use traps. Mealybugs show up as white cottony masses on stems and leaf bases. A strong spray of water knocks them off, or you can treat them with neem oil. Catching any pest problem early gives you the best chance of saving your plants from serious harm.
Most of these problems come back to two basic rules. Keep your soil well-drained and give your plants enough space for good air flow. I check my coral bells every week during the growing season, and that quick look catches problems before they get out of hand. A five-minute walk through your garden with a sharp eye is the best tool you have against every issue on this list.
Read the full article: Coral Bells: How to Grow and Care Guide
