Choose seeds that are appropriate for the environment of your rock garden, such as full-sun or part-shade. Rock garden plants tend to be low-growing, drought-tolerant perennials and shrubs that grow well in a rocky environment.
A low-cost way to access rock garden seeds is through collecting them from a rock garden or wild area. Collect no more than 10 percent of the available seed at a given time so as not to disturb the plant population. Unless the plants belong to you, collecting requires permission. In the case of public lands, seed collection permits are mandatory.
Seed exchanges are a way to trade seeds with other gardeners. Organizations such as the North American Rock Garden Association facilitate large-scale seed exchanges that are excellent sources for obtaining rock garden seed varieties, from the common to the rare and unusual.