Should I cut off all the spotted leaves?

Yes, it is best to prune away heavily spotted fronds to prevent the fungus from moving to healthy parts of the plant.

Can I use a fungicide on my fern?

It is usually better to fix the environment first. If you must use one, choose a mild organic copper fungicide and test it on one leaf first.

Rattlesnake fern: spots, causes and fixes

Check these first

Inspect the undersides of the leaves for fuzzy growth.
Check if the soil is waterlogged or swampy.
Ensure the plant is not crowded by other foliage.

Likely causes

Fungal leaf spot
Most likely
How to tell: Small dark or black spots appear on the fronds, often with a yellow halo. This happens when the foliage stays wet for too long.
What to do: Remove the affected fronds immediately to stop the fungus from spreading. Improve air circulation around the plant and avoid misting the leaves directly.
Overwatering
Possible
How to tell: The soil stays soggy and the spots may feel soft or mushy. This creates the perfect humid environment for fungal spores to thrive.
What to do: Allow the top inch of soil to dry out slightly before watering again. Ensure your pot has drainage holes so excess water can escape.

Leaf spots on other plants

Find out what's wrong with your rattlesnake fern

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

Worry if the spots are spreading rapidly across multiple fronds. A single spot on an old leaf is usually nothing to panic about.

Stopping it coming back

Water only the soil at the base of the plant rather than pouring water over the fronds. Keep the area well ventilated.

Rattlesnake fern: spots? Check yours with a photo

Every plant is a little different. Take a photo of your rattlesnake fern 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 cut off all the spotted leaves?: Yes, it is best to prune away heavily spotted fronds to prevent the fungus from moving to healthy parts of the plant.
Can I use a fungicide on my fern?: It is usually better to fix the environment first. If you must use one, choose a mild organic copper fungicide and test it on one leaf first.

Guides to these causes

Leaf Spot

Why does my Rattlesnake fern have dark spots on its leaves?