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Canna lily · Canna × generalis

Why does my Canna lily have orange spots on its leaves?

Those little orange dots are a classic sign of Canna rust, a fungal infection that loves humid conditions. Check the undersides of your leaves to see if the spots are powdery or raised.

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spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Inspect the underside of the leaves for orange dust.
  2. Check if the plants are crowded together.
  3. Look for signs of moisture sitting on the leaves.

Likely causes

  1. Canna Rust

    Most likely

    How to tell: You will see small, bright orange or rust colored pustules on the leaf surface. These often appear when the plant is crowded or the air is very humid.

    What to do: Remove and destroy the infected leaves immediately to stop the spread. Improve air circulation around the plant by spacing them further apart. Avoid overhead watering to keep the foliage dry.

  2. Fungal Leaf Spot

    Possible

    How to tell: These spots are usually darker, often brown or black with a yellow halo. They appear when the foliage stays wet for too long.

    What to do: Prune away the affected leaves to prevent further spread. Apply a copper based fungicide if the issue persists. Always water at the base of the plant to keep leaves dry.

Leaf spots on other plants

Find out what's wrong with your canna lily

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.

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When to worry

If the spots cover more than half the leaf surface, the plant will struggle to photosynthesize. It is normal to see a few spots on older, lower leaves as the season ends.

Stopping it coming back

Space your plants well to ensure good airflow and always water the soil directly rather than spraying the leaves.

Canna lily: spots? Check yours with a photo

Every plant is a little different. Take a photo of your canna lily 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.

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Questions people ask

Will these spots kill my plant?
Usually no, but they can weaken it significantly. If left untreated, the plant may lose its vigor and produce fewer flowers.
Can I compost the infected leaves?
No, do not compost them. The fungus can survive in the pile and spread back to your garden next year.

Guides to these causes

More problems with Canna lily

Back to the Canna lily guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.