Seeds Exposed to Mold

Fermentation

• Some seed-saving techniques actually involve mold in a positive way. Tomato (Solanum lycopersicum) seeds are surrounded by a thick protective gel, and fermentation breaks it down without damaging the seeds. Mold forms on the gel's surface as fermentation happens. Exposure to that mold won't harm the seeds if they are properly rinsed and dried afterward, but subsequent infections could ruin those seeds' viability.

Damage

• Both homegrown and commercially purchased seeds can develop mold after they are stored. Even if the mold appears to stay on the seeds' surface, it can damage the seeds' interior. Seeds with moisture lingering in their cores attract fungi that have evolved to grow there. Also, spores of molds that target them can enter a seed supply from insects or other pests.

Drying Procedure

• Drying seeds properly before putting them into storage is the main tactic to stop mold damage. When you gather seeds from a garden, start with ripe fruits and vegetables, and try not to let the specimens rot in the garden. Seed heads or seedpods from flowers should be well-dried before they are opened. Allowing peppers (Capsicum annuum) to dry in a moist climate, however, could lead to seeds with a coating of mold, according to a University of California Sonoma County Master Gardeners website article. Spread gathered seeds on paper towels or a mesh that will wick moisture from the seeds, and turn the seeds regularly to allow them to dry evenly.

Prevention

• Commercial seeds are well-dried, but they still can mold if stored improperly. Use paper envelopes to hold each seed variety because moisture can escape through the paper. A University of Nebraska-Lincoln Lancaster County Extension online article recommends placing seed envelopes in an airtight container with a material that absorbs moisture. The moisture-absorbing material can be silica gel, a different flower-drying medium or 2 heaping tablespoons of powdered, nonfat dry milk contained in a few layers of facial tissue. Dry seeds won't develop mold or germinate in the airtight container. Storing the container in a refrigerator or other location with a temperature below 60 degrees Fahrenheit but above freezing slows the development of mold.