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Bulb Rot

Disease

Bulb rot is a fungal or bacterial infection that attacks the underground storage organs of plants. It is a serious issue because it destroys the plant's ability to store energy and absorb water, which often leads to total collapse.

Symptoms by part

Roots

The bulb or corm feels soft or mushy to the touch and may emit a foul, swampy odor. You might see dark, sunken lesions on the outer scales or a white, fuzzy fungal growth covering the surface.

Causes

  • Poor soil drainage that leaves bulbs sitting in standing water.
  • Overwatering during the plant's dormant phase.
  • High humidity levels in storage areas.
  • Mechanical damage to the bulb during planting or digging that allows pathogens to enter.

Could be confused with

  • Bulb Mite infestation · Mites are tiny pests visible with a magnifying glass, whereas rot is a tissue breakdown often accompanied by a distinct smell.
  • Natural dormancy · Dormant bulbs remain firm and healthy, while rotting bulbs become soft and disintegrate.

Treatment

  1. Carefully dig up the affected bulb and inspect the extent of the damage.
  2. Use a sterilized knife to cut away any soft or discolored tissue until you reach firm, healthy material.
  3. Allow the remaining healthy portion of the bulb to air dry in a shaded, well ventilated spot for 2 to 3 days until the cut surface callouses over.
  4. Replant the bulb in fresh, fast draining soil in a new location.

Without chemicals

  • Improve soil drainage by adding grit or perlite to the planting hole.
  • Remove and destroy any bulbs that are more than half rotted.
  • Ensure proper spacing between bulbs to allow for better airflow.
  • Use a rain cover or cloche over susceptible plants during periods of excessive rainfall.

Preventing it

  • Always plant bulbs in soil that drains quickly.
  • Avoid watering bulbs while they are in their dormant stage.
  • Inspect bulbs for soft spots or damage before planting them.
  • Store harvested bulbs in a cool, dry, and well ventilated environment.

Season

The warm growing season, especially when soil temperatures are high and moisture is trapped.

Spread risk

Moderate

Severity

High

When to act

Act as soon as you notice wilting or soft growth above the soil line. If the entire bulb is mushy or smells strongly of decay, remove and discard the plant immediately to protect neighbors.

Think it's Bulb Rot?

This guide covers the general picture. Pocket Botanist looks at your actual plant from a photo and tells you what's really going on, how serious it is, and what to try first. Identification and a health check are free.

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Questions people ask

Can I save a bulb that has started to rot?
Yes, if you catch it early enough. If the rot has not reached the center or the basal plate, you can cut away the infected tissue and let the bulb dry before replanting.
Why do my bulbs rot even when I do not water them much?
The issue is likely the soil type. If your soil is heavy clay, it holds onto moisture for too long, creating the perfect environment for rot even without extra watering.

Plants it affects

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This guide was generated with AI and is general information, not horticultural advice. Read about how we build these guides.