The Q&A Archives: White "Stuff" on Seed Starting Mix

Question: About a month ago, I started 8 flats of flowers from seed in my basement using seed starting mix, bottom watering, fluorescent lights, and Burpee seeds. The seeds include delphinium, statice, impatiens, gloriosa daisy, coreopsis, and others. The germination rate has been excellent and the seedlings look healthy so far. My concern is that the top of the seed starting mix is turning white. I remove the plastic covers from my seed trays as soon as germination occurs. What is causing this and should I be concerned? This happened last year also. Thanks for any advice - this is a great resource! Diane Robinson Simsbury (aka Tariffville),CT

Answer: If you are fertilizing and watering from the bottom, then the white stuff would be a buildup of fertilizer. Water from the top until water runs out the bottom of the flat. This flushes the soil of any fertilizers that may have built up in the media. Another explanation may be that you are overwatering and mold is growing on the surface of the soil. Let the soil dry out somewhat between waterings. Stick your finger in the soil. You can feel the moisture. The soil doesn't have to be soaking wet. Anyway...remember that roots need oxygen and too much water will inhibit growth and eventually kill the seedlings!

« Click to go to the homepage

» Ask a question of your own

Q&A Library Searching Tips

  • When singular and plural spellings differ, as in peony and peonies, try both.
  • Search terms are not case sensitive.

Today's site banner is by cocoajuno and is called "Here's looking at you."