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Growing healthy seedlings

M. Grabowski, UMN Extension Educator
M. Grabowski, UMN Extension

As the growing season approaches, many gardeners are starting seeds indoors and making plans for direct seeding in the garden. Unfortunately, damping off, a common disease of seedlings, can dampen dreams of garden fresh produce by killing plants before they get started. Here are a few critical steps that gardeners can take to ensure a healthy crop of sturdy seedlings ready to face the growing season.

  1. Use clean pots. It is o.k. to reuse old pots and trays but wash them first. Scrub out any old soil and plant roots. Soak the pots in solution that is one part bleach and nine parts water for 10-30 minutes. Then rinse in clean water. 
  2. Purchase new potting mix designed for seed starting. Potting mix that has been previously used often contains low levels of plant pathogens. Newly emerged seedlings have little to no natural defenses and quickly succumb to these pathogens. 
  3. Warm the soil with a heating mat designed to go below planting trays. If seeding directly into the garden, wait until the soil temperature has warmed to the optimal temperature for germination (70 F or greater for most vegetables). 
  4. Keep soil moist but not soggy. Seedlings need moisture to germinate and grow but too much water will encourage damping off pathogens. Use a potting mix that drains well. Pots should have drain holes that allow excess water to drain off.
  5. Water with warm water. Cold water slows plant growth and keeps seedlings in a vulnerable stage for a longer period of time. Warm water to 68-77 F before watering plants.

The key to success is to provide seedlings a clean environment and optimal conditions for growth to help them quickly grow out of the vulnerable seedling stage and into a study healthy transplant.

Learn more about Starting seeds indoors
Learn more about Damping off of seedlings

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