Are these spots contagious to other plants?

If the spots are fungal, they can spread through water splashes or wind. Keep infected plants isolated until the issue is resolved.

Do I need a fungicide?

Usually, improving airflow and removing infected leaves is enough. Only use a fungicide if the infection is severe and spreading rapidly.

Poison hemlock: spots, causes and fixes

Check these first

Inspect the underside of the leaves for small insects.
Check if the leaves are staying wet for long periods after rain or watering.
Look for signs of mold or fuzzy growth on the spots.

Likely causes

Fungal leaf spot
Most likely
How to tell: Small dark or discolored spots appear on the leaves, often with a yellow halo. These spots may grow larger if the foliage stays wet for too long.
What to do: Remove the affected leaves immediately to stop the spread. Improve air circulation around the plant and avoid overhead watering to keep the leaves dry.
Aphid damage
Possible
How to tell: Tiny yellow or pale spots appear where aphids have been feeding on the sap. You may see small insects clustering on the undersides of the leaves.
What to do: Spray the plant with a gentle stream of water to knock the aphids off. For heavier infestations, apply insecticidal soap according to the label instructions.

Find out what's wrong with your poison hemlock

The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.

When to worry

Spots can spread quickly and weaken the plant if left untreated. It is normal to see minor cosmetic blemishes on older leaves as the season progresses.

Stopping it coming back

Water at the base of the plant to keep foliage dry and ensure there is plenty of space between plants for air to move.

Keep your poison hemlock healthy from here

Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked. Identification and a health check are free.

Get the app · Or check it from a photo now, free

Questions people ask

Are these spots contagious to other plants?: If the spots are fungal, they can spread through water splashes or wind. Keep infected plants isolated until the issue is resolved.
Do I need a fungicide?: Usually, improving airflow and removing infected leaves is enough. Only use a fungicide if the infection is severe and spreading rapidly.

Why are there spots on my poison hemlock leaves?