What's Eating Your Hellebore?

Strong water blast every 2 to 3 days for 2 weeks

Hold a hose nozzle 12 inches from the affected flower stalks and spray at moderate pressure. Hellebore stalks are sturdy and tolerate a firm rinse without bruising the blooms. Most aphids dislodge and don't make it back. Repeat every 2 to 3 days for 2 weeks. Wear gloves while you work because every part of the plant is toxic to skin.

Insecticidal soap on stalks and bloom backs, weekly

Spray ready-to-use insecticidal soap (Safer Brand, ~$10) directly on the colonies coating the flower stalks and the underside of the petals. Spray at dusk so the soap doesn't dry too fast in sun. Repeat weekly for 3 weeks to catch newly hatched nymphs. Avoid open flowers when pollinators are visiting.

Wear gloves and snip the worst stalks

If a few flower stalks are completely coated, cut them off at the base and bag them. Always wear gloves when handling any part of a hellebore. The cardiotoxic alkaloids in the sap can irritate skin and are dangerous if they reach your eyes or mouth. Removing the worst stalks reduces the colony quickly without spraying near the rest of the bloom.

Iron phosphate bait around the clump

Scatter iron phosphate slug bait (Sluggo or Garden Safe, ~$12) in a thin ring on the soil 6 inches out from the crown. Refresh after rain. Iron phosphate is safe for pets, birds, and beneficials, which matters near a plant whose own toxicity is the only thing keeping deer and rabbits at bay. Avoid metaldehyde baits because they're dangerous to dogs.

Hand-pick at dusk and after rain

Pull mulch back from the crown in spring

Hellebores like a cool root run, but a thick mulch ring pushed right against the crown gives slugs a perfect daytime hide. Pull mulch back 3 to 4 inches from the base of the clump as growth resumes in late winter. The exposed soil dries out faster between rains and slugs avoid the dry zone.

Water deeply and shade the clump

Spider mites on hellebore are almost always a symptom of heat and drought stress, not a pest problem on their own. Soak the root zone deeply once a week through any summer dry spell. Shade-loving woodland conditions are what hellebores want anyway. Fix the underlying stress and the mites usually clear without spraying.

Rinse leaf undersides weekly for 3 weeks

Spray cool water on the underside of every leaf with a hose nozzle for 30 seconds per clump. The thick leathery hellebore leaves tolerate a hard rinse well. Mites can't reattach quickly and the rinse humidity slows survivors. Repeat weekly for 3 weeks.