Dampening Damping-Off: Tips on Seed Starting to Avoid Disease

Image of nearly dead seedling
Damping off can kill your seedlings

By Brian Hudelson, Plant Disease Diagnostic Clinic

After a long, cold winter, it’s time to start growing plants from seeds for the upcoming growing season. Damping-off is a common disease that can prevent seed-starting success. Here are tips that can help prevent damping-off from being a problem.

Buy high quality seed from a reputable source. High quality seeds are less likely to carry damping-off organisms.

Use pasteurized soil. Pasteurized soil has been steam treated to kill pathogens.

Use clean pots/containers. Store new pots or flats in sealed plastic bags to prevent possible pathogen contamination prior to use. When reusing pots, soak them in 10% bleach (1 part of a disinfecting bleach, 9 parts water) for 30 minutes, then rinse well to remove bleach residues.

Plant seeds at the proper depth. This will promote quick germination and rapid growth of seedlings out of the early stages of growth when they are most susceptible to damping-off.

Start seeds at higher temperatures. This will again help plants grow out of their susceptible phase quickly. Consider using a seed-starting heat pad (available at your local garden center), particularly if you start seeds in a colder part of your home (e.g., a basement).

Don’t overwater! Damping-off organisms are more active in wet soils. Water enough to keep seedlings alive, but keep plants a bit on the dry side to slow development of damping-off pathogens.

Seed starting can be a fun way to start the gardening season. With just a little extra effort, you can prevent damping-off from dampening your gardening efforts.

For more information on damping-off and its management, check out University of Wisconsin Garden Facts XHT1124 (Damping-Off), available at https://pddc.wisc.edu/fact-sheet-listing-all/ or https://hort.extension.wisc.edu/articles/damping/.

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