First off, which species of Chlorogalum do you have? C. pomeridianum is apparently the species that was most used by native American tribes for multiple uses; including soap, fish poison and for wrapping food to be baked. It is widespread across the state of California, where it can be found in full sun or partly shaded woodlands. while other
species are localized to different parts of the west coast, including Baja California. As I've seen it in the wild, it grows in full sun in heavier clay loam soils, which would only receive moisture in the winter rainy season and be bone dry in summer. As it is a bulb, it may take several years to get large enough to use. As to how much to use for the purpose of soap, I'd suggest researching that in books on local Native American tribes such as the Miwoks, which might detail the cultural uses,I've no idea myself.I'm not sure how well adapted it would be to climates with winter snow and summer rain; but at least this most common species must be broadly tolerant as it grows all across the state from north to south and coast to Sierra Nevada foothills, only excepting the deserts and mountains above 5000 to 6000 foot elevations.