Are these spots a fungus?

Usually, these spots are caused by environmental stress rather than a fungal infection. Keeping the water clean and fresh is the best way to prevent them.

Should I use fertilizer to help?

Avoid fertilizing if you see spots, as excess nutrients in the water will only make algae grow faster. Focus on cleaning the water first.

Why are there spots on my Juncus bulbosus? Causes and fixes

Check these first

Inspect the water for any green slime or film.
Look for white or crusty residue on the lower stems.
Check if the water smells fresh or stagnant.

Likely causes

Algal Overgrowth
Possible
How to tell: Green, slimy film covers the base of the stems and the water surface. This blocks light and oxygen, leading to discolored, spotted patches on the lower stems.
What to do: Empty the container and scrub it thoroughly with mild soap and water. Rinse it well and refill with fresh, clean water to keep the stems healthy.
Mineral Buildup
Possible
How to tell: It is less common for this plant to get spots from minerals, but it happens when using hard tap water that leaves white or brown crusty deposits on the stems. These deposits can eventually cause the tissue underneath to brown or spot.
What to do: Switch to using distilled or rainwater for your rush. Flush the container every 2 weeks to prevent mineral salts from accumulating around the base of the plant.

Leaf spots on other plants

Find out what's wrong with your bulbous rush

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

If the spots are spreading rapidly and the stems are turning mushy, the plant is struggling with severe water quality issues. A few small marks are usually just a sign that the water needs a quick refresh.

Stopping it coming back

Change the water regularly every 3 to 5 days to prevent algae and mineral buildup. Keep the container out of direct, intense heat to slow down algal growth.

Bulbous rush: spots? Check yours with a photo

Every plant is a little different. Take a photo of your bulbous rush 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

Are these spots a fungus?: Usually, these spots are caused by environmental stress rather than a fungal infection. Keeping the water clean and fresh is the best way to prevent them.
Should I use fertilizer to help?: Avoid fertilizing if you see spots, as excess nutrients in the water will only make algae grow faster. Focus on cleaning the water first.

Guides to these causes

Salt Stress

Why are there spots on my Juncus bulbosus?

Check these first

Not sure what's wrong with your bulbous rush?