Saving leftover purchased seeds or saving your own seeds from the garden is a viable alternative to buying fresh seeds each year. Many seeds remain viable for up to five years if they are stored in the refrigerator or freezer and are kept dry. In order to successfully plant stored seeds, germination viability must be checked first. Otherwise, you may end up wasting time planting seeds that will not sprout. Testing and planting seeds after freezer storage requires only a little more time than getting started with newly purchased seeds.
Stack two paper towels on top of each other and then moisten them until they are damp but not dripping wet. Place 10 to 20 of the stored seeds on the paper towel. Fold the towel in half so the seeds have contact with the damp towel on both sides.
Place the towels and seeds into a plastic bag and seal it closed. Set the bag in a warm, 65 to 70 degree F room. Check the seeds after seven days and count how many have begun to sprout. If at least 70 percent have sprouted, the seeds are viable. If less than 70 percent have sprouted, leave the seeds alone for an additional seven days, and then check again. If it's still less than 70 percent, purchase new seeds.
Fill seed starting pots with clean potting mix. Sow seeds to a depth of twice their width and water thoroughly. Plant two seeds per pot unless you are attempting to grow stored seeds with poor germination rates. In that case, plant three to four seeds per pot.
Cover the pots with a plastic bag and set them in a warm, 65 to 70 degree F room to germinate. Most seeds germinate within seven to 14 days.
Remove the plastic bags once sprouts emerge and move the plants to a sunny window sill. Keep the soil moist but not soggy at all times.
Thin each pot to one plant once the seedlings produce their second set of leaves and are 2 to 3 inches tall. Cut off the weaker plants at soil level to remove them.
Transplant the seedlings to the garden after the last expected spring frost or when recommended for the particular plant type. Place seedlings outdoors for a few hours a day starting one week before transplanting to get them accustomed to outdoor temperatures.