Companion plants for Grevillea

I'm removing my lawn and planting drought tolerant plants. I found this Grevillea but am not sure which shrubs or other plants would look good with it. It will be 2' tall x 10' wide eventually. Any suggestions?

Nice Grevillea!

Grevillea in general are drought tolerant, and prefer low phosphate fertilizers.
While the ultimate size may be 10' diameter, this first summer and probably next you can plant a lot closer to it to keep the area filled in.
Or, plant things wider spread out, mulch in between plants, and run a drip system so that each plant is water individually.

Companion plants for Grevillea in our zones (I do most of my landscape designs for zone 9, a bit inland from you) will include pretty much all the plants usually thought of as drought tolerant such as:
Non-natives such as Lavender, Cistus, rosemary (I'll bet Tuscan Blue would look really nice with that yellow Grevillea), Teucrium, Leonotis, and many others.

Native plants: clump grasses such as Festuca californica, Juncus, and Carex, native shrubs such as the many Buckwheats (Eriogonum) and Manzanita (Arctostaphyllos). The native Ceanothus are good, too. If deer are common in your neighborhood get the smaller, prickly leafed Ceanothus, not the wider leafed types. There are many Ribes and Rhamnus. Carpenteria californica and Zauschneria californica are really nice shrubs, too. There are many native sages (Salvia and Artemisia).
Take a good look at the native plants (and non-native drought tolerant plants) in botanical gardens such as Strybing (San Francisco) Berkeley Botatincal Garden, and the native plant garden in Tilden Regional Park to be sure you like them. There are many drought tolerant plants native to the Mediterranean, South Africa, SE Australia and Chile that also grow well in our area.
Make sure the native plants and varieties you see are the drought tolerant species. Some (mostly native to the redwood forests and the north coast) are not drought tolerant when kept in the drier inland areas.

For color, look into some native mallows like Sidalcea, and short lived but colorful plants that can be direct seeded like California Poppies, Lupines and other 'wildfower mixes'

For ground cover, spreading plants that thrive with less than average water look into the many species and varieties of Thyme, Ice Plant (really- I know some people hate it, some love it. The fine leaved species can be very pretty), and some of the Nepeta (cat mints). Plant these in blocks or zones that can be efficiently watered while they are getting established. For example, if you are using Netafim's Tech line with emitters spaced 18" apart, then plant one ground cover plant every 18", just downhill from an emitter.

Drought tolerant plants can ultimately be grown in mild areas like Palo Alto with no summer water, as long as winter rains are adequate. So, in most average years you might use NO irrigation for a well designed drought tolerant landscape once the plants are established. In a drought year you might water once a month in the WINTER. Yup. WINTER. Duplicate the plants' native requirement for water during the cool season.

When you first plant these plants you need to remember that their roots are not wide spread and well established. They will need to be irrigated where the roots are. You will be watering them more than you might hope for through their first summer (maybe once a week if you can get them in the ground right away), and paying good attention to them through their 2nd summer (watering perhaps once a month). By then the roots will be wide spread and deep so they can get to whatever water there is below the surface. You might only need to supplement the winter rains, and maybe water just once or twice through the summer to keep them looking better. (Some plants go dormant or semi dormant in true drought, and look pretty ratty).

A drip irrigation system can use significantly less water than a conventional spray system if it is designed and installed right. The emitters need to be properly placed around the plants, and need to be the right flow rate for your soil.
The water needs to deep soak without run off. In a clay soil this might need to be run for many hours. But then the soil is wet and stays wet for a long time. It might be a month or more before you need to water again. In sandier soils you can run a faster emitter, but do not run it for very long. The water will soak right through the sandy soil, and carry away and fertilizer you have used. The water will flow beyond reach of the roots. Then you need to water again fairly soon.

As an example, the company Netafim makes Tech line with many flow rates per emitter, and different spacing of the emitters.

For maximum plant health under drought conditions I make a spiral around a new plant so the original root system is watered and expand the spiral after 1 year into a circle.

Mulch all the soil. This will keep it cooler in the summer, warmer in the winter, help it hold water, reduce soil compaction and erosion, and minimize the weeds. Top dress the mulch annually. It decomposes (further helping the soil).

UC Davis has a LOT of information about proper planting techniques, and irrigation for drought.
CIMIS is California Irrigation Management Information System, and is a system of monitoring stations throughout the state. It is geared toward farmers, but has monitoring stations in cities, too. It can tell you how much rain has fallen lately, and how this compares to the seasonal averages for as long as a station has been set up (several years for most of them). This will help you to figure out how to irrigate the landscape.

THANK YOU for such a thoughtful response! So much helpful info--I'm going to be referring back to it often. I feel a lot more confident getting started. I love that Grevillea, it's really striking. Now I just have to make up my mind about the other plants and get going. :)

THANK YOU for such a thoughtful response! So much helpful info--I'm going to be referring back to it often. I feel a lot more confident getting started. I love that Grevillea, it's really striking. Now I just have to make up my mind about the other plants and get going. :)

If you want to give more info for example a few pictures of the area, and your color preferences I think I could narrow down the plant choices and get some detailed varieties and so on.

Do you like the grassy look?
Actual ornamental grasses or wider blade plants that have sword shaped leaves?

Are you looking for anything tall enough to act as a screen or hedge?

Will there be a walkway through the area?

How much sun or shade?

Will you be installing irrigation?