As cold weather sets in and winter approaches, Iowa State University Extension and Outreach horticulturists share tips on how to prepare garden supplies for the season. Leftover flower and vegetable seeds can be stored for two to three years and still be viable. They should be kept in a cool, dry place and it is generally best to keep them in their original packets. The packets should then be placed in a tightly sealed jar or plastic lidded coffee can. Then place a small envelope with one to two tablespoons of powdered milk in the container to absorb moisture from the air. The container should be stored in a cool location, such as a refrigerator.