Ask Mr. Smarty Plants

From this USDA Plant Profile Map, you can see that Nassella tenuissima (Mexican feathergrass) has been reported as growing only in Contra Costa County, north of San Francisco, in California. That doesn't mean it won't grow in other places, it just means you need to pay close attention to the growing conditions this plant requires. From our webpage on Mexican feathergrass:

"Growing Conditions

Water Use: Low
Light Requirement: Sun , Part Shade
Soil Moisture: Dry , Moist
Soil Description: Well-drained, acid or calcareous sands, loams, or clays.
Conditions Comments: Requires good drainage and cant take excessive moisture. Should not be watered heavily more than once a week. Goes dormant during drought and in winter. May rot under heavy mulch. Grows well in containers."

In answer to your specific question, this says not more than once a week, so if your system is set to cover other areas that need more water, you could have problems. You are fortunate in that it can tolerate both acid or calcareous soils. A lot of it is grown in our area, and we definitely have alkaline and often clay soils. This is basically a desert plant and should certainly be a good plant for your environment, requiring less water; however, you really need to be sure about the drainage.

We would suggest you contact the University of California Cooperative Extension Office for Los Angeles County for information on what your soils are and how they could be amended. You can get a kit for a soil test; in some places you can get a service to do this for you. If you have a clay soil you will definitely have to take steps to improve the drainage. Clay is very tiny particles which absorb water and swell, thus shutting out oxygen which roots also need. Roots can quite literally drown. From a company called Bachman's here is an excellent article on Working with Clay Soils.

Until you know what your soil is, all these instructions will be of no use but if, as we suspect, you have a clay soil, we are big fans of compost and no, you don't have to have a compost pile although they are great fun if you have the room. You can buy good quality compost, and make sure it IS good quality, well decomposed and with a good odor. Then, with a rented tiller, you can improve a large area of soil and have a very good location for your Nassella tenuissima (Mexican feathergrass).

One final question for you: Do you have a source for purchasing full grown feathergrass? Most grasses are purchased as small plugs or seeds. Grasses have long fibrous roots, which is good because they will help to hold soil in place, but transplanting those roots could be a problem. Again from our webpage:

'Propagation

Propagation Material: Seeds
Seed Collection: Collect seed in May, June when it is blonde and comes away easily. Use a comb or your fingers to rake seed off in such a way as not to damage the look of the plant.
Seed Treatment: Can be started all year, but may grow faster in the heat.
Commercially Avail: yes
Maintenance: Water once a week during droughts to prevent dormancy. Do not cut it back after winter."