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Onion · Allium cepa

Why are my spring onion roots rotting?

Root rot is a serious condition usually caused by soil that stays too wet for too long. Check the smell and texture of the roots to confirm this issue.

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root rot on a plant
Photo: Ninjatacoshell, CC BY-SA 3.0

Check these first

  1. Smell the soil for a foul, swampy odor.
  2. Gently pull the plant to see if the roots are mushy.
  3. Check if the pot has standing water in the saucer.

Likely causes

  1. Waterlogged Soil

    Most likely

    How to tell: The roots look brown and slimy instead of white and firm.

    What to do: Repot the plant into fresh, well draining soil. Trim away any mushy or black roots before replanting.

  2. Basal Rot

    Possible

    How to tell: The base of the bulb turns soft and brown, often accompanied by wilting leaves.

    What to do: Discard the infected plant and the surrounding soil. Do not reuse the pot unless it has been thoroughly sterilized with bleach.

Root rot in other plants

Find out what's wrong with your onion

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 entire bulb is soft and smells bad, the plant cannot be saved. It is best to discard it to protect other plants.

Stopping it coming back

Use a light, airy potting mix and ensure your container has plenty of drainage holes.

Onion: root rot? Check yours with a photo

Every plant is a little different. Take a photo of your onion 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

Can I save a plant with root rot?
If only a few roots are affected, you can trim them and repot. If the rot has reached the bulb, it is usually too late.
How often should I water to prevent rot?
Water every 2 to 7 days depending on heat. Always check that the top inch of soil is dry before adding more water.

Guides to these causes

More problems with Onion

Back to the Onion 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.