One trade secret of landscape designers is knowing which plant combinations grow well and look good together. Grouping plants according to their sun/shade and water requirements is the first step. A shortcut is to look at plant communities.
For example, the coastal sage scrub plant community is especially adaptable to garden conditions. Coastal sage scrub plants grow in well-drained loose soils in full sun on the coast, where they are sculpted by the wind into rounded shapes and absorb moisture from the fog. They have tenacious root systems that are great for stabilizing slopes and controlling erosion.
In inland gardens, coastal sage scrub plants will grow in denser soils, especially if planted on mounds to ensure excellent drainage, but often are shorter-lived than on looser soils. In general, they prefer afternoon shade, or in full sun can tolerate some water.
Sages, sagebrushes and wild buckwheat are characteristic of this plant community. Plant flowering sages for bees and buckwheat for butterflies.
My favorite is Cleveland sage (Salvia clevelandii), which has a wonderful sweet sagey fragrance and gray-green leaves. It grows 3 to 5 feet, forming a mounded shape, and in the spring sends out masses of lavender flowers.
Bold, vertical white sage (S. apiana) has a basal rosette of silvery white leaves, with dramatic flowering stalks and a strong pungent fragrance.
With whitish gray leaves and rosy pink flowers, purple sage (S. leucophylla) is the biggest shrubby sage, growing 4 to 7 feet tall and wide.
California sagebrush (Artemisia californica) has fine, soft foliage and a strong sagey fragrance. A smaller plant better suited to most gardens is David's Choice sandhill sagebrush (A. pycnocephala "David's Choice").
A refined plant, Santa Cruz Island buckwheat (Eriogonum arborescens) forms a neat spreading mound usually 2 to 3 feet high, with white to pink flat-topped flower clusters that fade to brown in the fall.
Needlelike leaves distinguish California buckwheat (E. fasciculatum), which is smothered in white flowers from spring to summer, fading to rust or brown in the fall.
The biggest and boldest buckwheat is Saint Catherine's lace (E. giganteum), which has bigger leaves than the others as well as huge creamy flower sprays.
Red-flowered buckwheat (E. grande rubescens) is one of the easiest to grow, staying a foot or two tall and wide, and spreading through the garden.
Finally, sulfur buckwheat (E. umbellatum) is a reliable small plant with vibrant yellow flowers.
Two public gardens where you can see coastal sage scrub plants are Native Hill at Foothill College in Los Altos Hills, next to Parking Lot 5-A (bring 8 quarters for parking), and the California Garden on the Stanford campus, at the corner of Lomita Drive and Roth Way (free parking on weekends).