Seeds should be properly labeled and stored in a cool, dry location. Seeds can be kept in the refrigerator and then left out to warm up gradually to room temperature before planting.
Before storing seeds, determine if they are desiccation-intolerant or desiccation-tolerant. Seeds that are desiccation-intolerant usually die if they are allowed to dry out and are more complicated to store. These seeds are typically for trees, plants with large seeds and aquatic plants. Desiccation-intolerant seeds must be kept damp and cannot be stored for a long period of time.
Desiccation-tolerant seeds can generally be stored properly for months or years. These seeds need to be dried out without removing all of the moisture. If the seeds have too much moisture, there is a high risk of mildew growing and killing the seeds. Moisture can be regulated by storing the seeds with milk powder, rice or silica gel packets. These seeds need to be kept at a constant temperature and only altered gradually to cool for storage and warm prior to planting.
Different seeds have a range of storage lifespans when stored properly. Onions can be stored for one year. Garlic cannot be stored. Other seeds can be stored for up to three years.