The zonal geranium (Pelargonium x hortorum) is an annual plant that produces brightly colored blooms in a profuse display from spring until fall. This versatile plant grows well in all U.S. Department of Agriculture plant hardiness zones when planted after the threat of spring's last frost. Its height varies by cultivar, reaching 6 inches to several feet tall. Wild geraniums (Geranium maculatum) are perennials in USDA zones 3 through 8. Collecting seeds from your favorite geranium, whether zonal or wild, allows you to plant that type of geranium again and to plant it indoors early in spring to get a head-start on blooms for hanging baskets, containers and window boxes.
Pour a small amount of isopropyl alcohol on a washcloth, dampening it. Open the blades of pruning shears, separating the two cutting surfaces. Wipe both sides of both blades with the washcloth, disinfecting them. Wait about one minute for the alcohol to evaporate.
Select a geranium flower in full bloom. Hold pruning shears in one hand, and use your other hand to hold a small container underneath the flower's seedpod. The seedpod is a swollen area at the bottom of the bloom, and it contains seeds. Cut the stem just below the flower and its seedpod. Collect additional blooms, including the seedpods at their bases, in the small container by using the same method, but disinfect the pruning shear blades with isopropyl alcohol between cuts.
Lay the blooms flat on a paper bag in a sunny, dry area, such as a windowsill. Allow each bloom to fade, and snip it from its seedpod, using newly disinfected pruning shears. Allow the seedpods to dry and shrivel for a few weeks. They will turn brown.
Roll the dry seedpods gently between your fingers over a sheet of white paper, such as notebook paper, to catch the seeds. Allow the seeds to continue drying for a few weeks.
Place the dried geranium seeds in a paper bag. Store the bagged seeds in the bottom of a refrigerator until you want to plant them next spring after the threat of the last frost has passed.