Portulaca are profuse little summer bloomers, hard to miss in bright neon hues of yellow, salmon, red, rose, pink, orange and white. Sturdy plants that thrive in bright sunlight, portulaca grow in nearly any well-drained soil, in rock gardens, on difficult slopes, along a garden path or flower bed border or a patio container. It isn't difficult to harvest seeds from healthy portulaca at the end of the growing season. Plant the seeds for a new display of color next year.
Allow a few portulaca blooms to wilt naturally on the plant at the end of the blooming season. Choose blooms from the healthiest plants. Leave the blooms on the plants as long as possible, until they die and turn brown. Keep a careful watch on the blooms, as waiting too long will mean the seeds may be expelled onto the ground.
Harvest the wilted blooms on a dry day, and never harvest damp seeds. Cut the blooms and drop them in a paper sack. Close the top of the sack and place the seeds in a warm room for one to two weeks.
Empty the contents of the bag into a strainer. Shake the strainer over a mixing bowl to separate the tiny seeds from the plant debris. The seeds should be hard and brittle. If necessary, leave the seeds in the bowl for a few days until the seeds are completely dry.
Place the seeds in a small paper envelope. Label the envelope so you'll know the type and color of the plant and the date the seeds were harvested. Store the seeds in a cool, dry place until spring.