The Q&A Archives: Mildewing Soil And Seeds

Question: I started seeds indoors (broccoli, lavender, collard greens and a few others). I covered them with plastic just like the package instructed, then checked on them around 5 days later and there was mildew on the soil. What can I do? What did I do wrong? Also can I salvage the seedings? HELP! I put so much work into getting them started.

Answer: It sounds like your seedlings are "damping off". Lifting the plastic once each day to provide fresh air would discourage fungal growth. Here are a few methods you can try, to help you avoid the problem in the future. Remove any seedlings that are diseased, to keep the problem from spreading to the other plants.

Since the fungus enters the plant at the soil line you can try to make an inhospitable environment for the fungus. When the seeds are planted, but before they germinate, cover the soil with a fine layer of "play sand" (this is sand that has been sterilized; you should be able to find it at a hardware store or lumberyard). This provides a sterile, dry -- and therefore unfavorable to the fungus -- surface at the point it usually enters the stem. Provide good, very good, air circulation (a fan blowing gently in the room--but not directly on plants--is one way), and be sure not to overwater. Another trick is to hold off on fertilizing the seedlings until their second set of leaves appear.

If you use a sterile medium (and it's a good idea to do so), sterilize your pots before planting with a 10 percent bleach solution, and follow the above steps, you should not need to apply a fungicide.

Also, once the plants have germinated, it's best keep them under the lights for about 16 hours per day. Keep the lights close to the tops of the seedlings--just an inch or two above the tips.

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