Disease organisms (fungi and/or bacteria) may kill seedlings during germination. Thus the medium, container, tools, and even the seed should be sterile. Commercial media are usually sterile when purchased.

The following suggestions should help prevent disease problems:

1. Use seed treated with fungicide. Seed packets are usually clearly marked when seeds have been treated with fungicides. Treated seeds are generally brightly colored (pink, purple, green).
2. Do not plant seeds deeper than necessary.
3. Keep temperature constant.
4. Provide seedlings with adequate ventilation.
5. Avoid overwatering.