Lettuce seeds are small and must be separated from the chaff when they are harvested. Once you have harvested your lettuce seeds, you will need to properly store them for the next growing season. Once that season arrives, you will need to prepare your lettuce seeds for planting. This is fairly easy to do, even if you are not an expert gardener.
Set your lettuce seeds on a paper towel for two to three days to dry them out.
Place the lettuce seeds in an envelope, and seal it shut.
Put your dry milk in a cloth bag and place it in an airtight container. Place your envelope filled with seeds on top of the cloth bag, and seal the container shut.
Store the seeds in the refrigerator until you are ready to plant them.
Remove the seeds from the refrigerator, and plant the seeds in tilled soil that has been mixed with manure. You should place 10 lettuce seeds every 12 inches into a hole that is half an inch deep.