Trailing petunias are compact, rambunctious plants that work well as a ground cover, or in a hanging basket, where the colorful miniature blooms will cascade gracefully over the side of the container. Saving seeds from trailing petunias is an easy process, and the seeds can be started indoors the following spring. Keep in mind that the blooms may not match the colors of the blooms on the parent plant.
Tie a colorful piece of yarn around the stems of a few healthy trailing petunias. Allow these petunias to die back naturally until they are brown and wilted.
Hold a large paper bag under each spent bloom, then snip off the bloom and let it fall into the bag. Put the paper bag in a cool, dry place for two weeks, shaking the bag occasionally. If you're collecting more than one type or color of trailing petunia, be sure to label the paper bag.
Remove the trailing petunia blooms from the bag and locate the seed pod at the base of the dry bloom. Split open a pod, and remove the small, brown seeds that will look like tiny balls. The trailing petunia seeds should be dry and hard, but if not, return the bag to the cool, dry place for a few more days, and check again.
Remove the dry seeds from the pods, and put them in a labeled white envelope. Store the envelope in a dry, cool place until spring.