Should I use a fungicide?

Fungicides are rarely necessary for Siberian Irises. Good garden hygiene and proper spacing are much more effective.

Can I compost the spotted leaves?

No, do not compost them. The fungal spores can survive the composting process and spread back to your plants.

Siberian iris: spots, causes and fixes

Check these first

Examine the leaves for small brown or black lesions.
Check if the foliage remains wet for long periods after rain.
Look for signs of overcrowding that block airflow.

Likely causes

Fungal Leaf Spot
Most likely
How to tell: Small brown or black spots appear on the leaves, sometimes with a yellow halo. In severe cases, the foliage may die back prematurely.
What to do: Remove and destroy all infected leaves to prevent the fungus from spreading. Improve air circulation around the plants by thinning out nearby vegetation.
Poor Air Circulation
Possible
How to tell: The foliage stays wet for long periods after rain or watering. This creates the perfect environment for fungal spores to thrive.
What to do: Avoid overhead watering to keep the leaves dry. Space your plants properly when planting to allow breezes to dry the foliage.

Leaf spots on other plants

Find out what's wrong with your siberian iris

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

Small spots are common in late summer and are usually not fatal. Worry only if the entire plant turns brown or the spots appear early in the spring.

Stopping it coming back

Clean up all dead foliage in late autumn to remove fungal spores that overwinter in the garden debris.

Siberian iris: spots? Check yours with a photo

Every plant is a little different. Take a photo of your siberian iris and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.

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

Questions people ask

Should I use a fungicide?: Fungicides are rarely necessary for Siberian Irises. Good garden hygiene and proper spacing are much more effective.
Can I compost the spotted leaves?: No, do not compost them. The fungal spores can survive the composting process and spread back to your plants.

Guides to these causes

Leaf Spot

Why are there spots on my Siberian Iris leaves?

Check these first

Not sure what's wrong with your siberian iris?