Repetition of form and color in the garden
I thought I might link to a more recent photo of a garden I designed and installed back in October of last year, which has finally filled in to give the effects I visualized when I was first planting it. The photo illustrates how the various plants were used to complement each other with similar forms and a blend of similar colors as well. I started off with a setting that already had some mature specimens in it, including the orange blooming Pincushion Protea(Leucospermum) and the spikey Sotol(Dasylirion wheeleri, as well as the New Zealand Flax. The new design for this slope incorporated these existing plants as well as moving many others of the clients' existing succulent collection to mass them more effectively to provide better contrasts of form and color. Previously the very dominant rock outcrop was partially obscured by large Phormiums and other shrubs in the foreground, which I removed and replaced with smaller clumping succulent rosettes and trailing succulents to frame the rock rather than try to hide it. Temporary color in this setting comes from annuals such as the Sweet Alyssum and Sea Lavender(Limonium perezii), which are place holders until the slower growing specimen succulents achieve mature sizes.
Here is a link that might be useful: Plant massing to emphasize texture and color