According to the Local Seed Network Manual produced by The Seed Savers' Network, to ensure longevity of a variety, they recommend:
What factors affect the length of time seed stays viable in storage?
The ideal conditions are:
1. A dark, dry environment - Seeds absorb moisture in humid environments and dry out in dry atmospheres. This results in a variety of problems including insects becoming active and reproducing (at 8-9% moisture); fungi growing on and in the seed (at 12-14% moisture); heating occurring (at 18-20% moisture); and at 20%+ moisture, seeds may start to germinate.
The manual says: "High seed moisture is the most common single cause of loss of viability and of vigour in storage." So how do you avoid this?
Tip: Store properly dried seed in moisture-proof containers and add rice or gel sachets to absorb any excess moisture.
2. Pest free - Select a secure storage space that rodents and insects for example can't access. Managing moisture will also avoid the rapid build up of insect populations. Weevils and other insects can be excluded by removing moisture and oxygen from your storage container.
Tip: To ensure weevils are not already present in your seeds before storing, add thoroughly dry seeds to the freezer in a sealed container for 2 days - this should kill most weevils and eggs.
3. Cool AND constant temperature - Seed vitality is best, the cooler the temperature. At 5 degrees centigrade and below, insects are inactive. So if you are storing seeds in your fridge, be aware that large fluctuations in temperature can reduce the seed viability.
Tip: Store in a cool environment like your fridge but try to avoid taking the seed in and out of it as maintaining a constant temperature is just as important to seed viability.
Hope these tips help you store your seeds successfully.
By Anne Gibson