How to Avoid Damping-Off

Damping-off causes seedlings to collapse soon after they emerge from the soil.
Damping-off causes seedlings to collapse soon after they emerge from the soil.

Damping-off is the term gardeners use to describe the wilting and death of seedlings just before or just after they emerge from the soil. 

Seedlings that suddenly collapse or fall over or bare spots in containers or in the garden where seeds were sown but never appeared are signs of damping-off.

Emerging seedlings
Emerging seedlings before they were attacked by damping-off.

Damping-off is not caused by one specific organism–as is the case with most plant diseases. Rather damping-off is caused by one of several fungi that live in the soil very close to the surface. The fungi most often enter the seed or plant in soil moisture. The fungi inhibit the uptake of moisture causing plant cells to rot.

Seedlings attacked by damping-off usually shrivel and their stems become dark and water-soaked. Seeds attacked by damping-off rot.

There is no cure for damping-off. Seeds or seedlings attacked by damping-off can not be saved.

Prevention is the only way to prevent damping-off for infecting seeds or seedlings. If a part of a seedbed is infected with damping-off, stopping the spread of the disease is possible.

Ways to Prevent Damping-Off

Here are ways to prevent damping-off:

  • Use a commercial sterile potting mix that contains no soil. Soilless starting mixes are available at garden centers.
  • Use new containers to start seeds or disinfect used containers before sowing seeds. Soak used containers for at least 15 minutes in a solution that is 1 part bleach and 9 parts water.
  •  Do not plant seeds in cold, moist garden soil. Make sure the soil is well-drained.
  • Make sure there is good air circulation where seeds are started. Still air and humidity can encourage the growth of fungi.
  • Maintain proper spacing between seedlings. This will allow for good air circulation and plenty of light.
  • Let the seed starting mix or soil just dry out at the surface between waterings.
  • Bottom water seed starting containers. Do not water overhead. Make sure seedlings started in the garden dry out before nightfall.
  • Avoid touching the stems of seedlings when transplanting. Use a small spoon to lift and move seedlings. Try not to disturb rootballs; transfer seedlings with as much starter planting mix as possible.
  • If damping-off is in a garden bed, remove infected plants immediately. Heat horticultural sand and sprinkle between seedlings to help prevent the spread of the fungus.

More articles on plant diseases at Diseases Category.






Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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