The passion flower vine (passiflora) is an exotic old-fashioned beauty that will happily climb over a trellis, fence or wall. Although the passion flower vine is a warm-weather plant, it can be grown as an indoor plant in climates where winter temperatures regularly fall below freezing. Although passion flower vine is usually propagated by stem cutting, it can easily be grown from seeds.
Wait until the passion flower vine produces fruit in late summer. The fruit will be oval-shaped and 1-1/2 to 3 inches in length and will have a smooth, waxy covering. Harvest the fruit when it's completely ripe and nearly ready to fall from the vine.
Slice the passion flower fruit in half with a sharp knife. The rind will be tough. Scrape out the seeds and pulp with a spoon and place them in a fine sieve. Each fruit can have up to 250 small, round black or brown seeds.
Rinse the passion flower seeds with warm running water, removing as much pulp as possible. Cover a tray or a baking sheet with waxed paper and spread the seeds on the tray.
Place the passion flower seeds outdoors in a shady spot and allow the seeds to dry completely. When the seeds are dry, they will be hard and brittle.
Store the passion flower seeds in a paper envelope. Label the envelope and place it in a cool, dark well-ventilated spot until spring.