Nurseries, mail- order houses and specialized cactus societies usually have cactus seeds available at a relatively low cost. Seed may also be collected from any cactus plant that has flowered either in your home, or in nature, by simply removing the ripe pods. Fully mature pods should be cut open, and the seeds squashed out onto a piece of paper towel where they can dry at normal room temperature. Rapid drying of the seeds will reduce the chances of rot occurring. If you plan to store the seeds for any length of time, they must be fully air-dried before being placed in storage.
Early spring is the best time to sow cactus seed.
This is because seedlings that germinate in springtime have the benefit of summertime light levels in which to establish themselves. Whatever container is used, it should be filled nearly to the top with rich, free-draining cactus soil. After firming the growing medium, seeds can be evenly spread on top. The seeds can then be covered by sifting a very thin layer of sand over top of them. The layer of sand should be very thin, and should permit at least a small amount of light to reach the seeds.