Beginner Gardening: New House, Clean Slate!, 1 by Diana_K

Diana_K wrote:
Research the plants.

California's central valley gets it rain in the winter. No rain in the summer, and 100*F days.
Things like Dianthus, most Clematis and Hydrangea are not drought tolerant under those conditions.

Look into plants that are native to Mediterranean climates such as California (but the right areas, not the mild north coastal zones), South Africa, certain parts of Australia, Chile and of course the Mediterranean itself.
These plants can be very showy, fragrant and lush looking without the water demands of many plants that came from wet summer areas.

For example, the Spanish Lavender (L. stoeches), many Phlomis, Buckwheat (Eriogonum) and Cistus (rock rose) are high on my list of plants that thrive with less summer water, and still can look really nice. Ornamental grasses can work, too. Especially look into some native Sedges like Carex testacea, and the native bunch grass Festuca californica 'Serpentine Blue'. Larger shrubs like Leonotis leonuris, Leptospermum and Cistus are good background plants. The cultivated forms of Rhamnus such as R. californica 'Eve Case' take a little more water than the original species, but are still a lot better than most of the plants used where summer water is available.
It won't be an English Cottage Garden, but a California Cottage Garden.
Achillea, Coreopsis, Lupinus, native Penstemon, Catmints, Thyme, and many more are good perennials for such a setting.

For dry part shade look into Mahonia, Nandina, Euonymus fortunei, Coprosma, or Arctostaphyllos. Some of these are more drought tolerant than others. The native Ribes, Rhamnus and Arctostaphyllos are good with no summer water.

Plant the most thirsty plants next to the lawn where the sprinkler over spray will help.
Lay out the lawn in a pattern that the sprinklers will cover with the least waste. This is squares, rectangles. Then take a sort of bite out of the edge of the lawn and plant thirsty flowers in there.
Here is a VERY simplified concept. Obviously you would want a much nicer layout, but the concept is valid.