Can Ziploc bags preserve seeds effectively?
Written by
Benjamin Miller
Reviewed by
Prof. Charles Hartman, Ph.D.Freezer-grade Ziploc bags give minimal protection to seeds when used with desiccants, and are only practical for 1-2 years. I have been able to store bean and pea seeds in plastic bags, but I learned the hard way just how temporary this method of storage is, as my seeds molded. However, with proper procedure, this method can be effective. This will vary from success to moldy failure and loss of valuable seed.
Preparation Essentials
- Select only freezer-grade bags (3+ mil thickness)
- Dry seeds thoroughly to 8-10% moisture content first
- Double-bag for extra protection against punctures
Desiccant Management
- Use 2 silica packets per quart-sized bag
- Check monthly for color change indicating moisture saturation
- Replace annually regardless of visible changes
Storage Protocol
- Remove air completely using straw suction method
- Store flat in cool, dark locations below 70°F
- Avoid temperature fluctuations exceeding 10°F
Moisture intrusion is the downfall and Achilles heel of Ziploc bags. Even with silica packets in my bags, after just a few months during humid summers in the Midwest, I would eventually (months) develop internal condensation in bagged food. Glass jars handle those same summers and stay dry for years. Freezer bags inhibit vapor transmission, but they don't stop it completely, unlike airtight containers.
Implement monitoring routines for seeds stored in Ziplock bags. Conduct germination tests every six months using 10 seeds on a damp paper towel. Observations indicate that viability decreases approximately 15-20% faster in bags than in jars. For essential varieties, such as family heirlooms, consider converting to glass within the first year.
Ziploc bags aren't great for decades of storage, but they work fine for short-term projects. They are great for Ohsomano seed swaps or to store trial varieties. For your main seed collection, combine it with desiccants and replace the bag annually. This strategy saved my experimental melon hybrids until I got proper jars.
Strategically use Ziplock bags, rather than relying solely on them. More specifically, I reserve them for temporary storage of high-germination seeds. I transitioned to glass containers to preserve varieties that would never have survived in plastic. Gardening success lies in striking a balance between convenience and protection.
Read the full article: 5 Essential Tips: How to Store Seeds Properly
