Add organic matter and nutrients as tests indicate. Materials with possible weed seeds should be composted thoroughly. N ratio material can help tie up excess nitrogen which encourages weeds. Direct seeding for shrubs rarely works well as many shrubs have long stratification requirements. Hydroseeding rarely works well in this dry environment, but a double spray with seeds in the first mix churned into the soil and then buried with a second spray with wood fiber can be much more effective than a single application.
Timing is critical for hydroseeding.
Ideally spraying will be done a day before gentle rains begin, or after soaking rains. Plant into prewetted, augered holes. On large denuded, ice plant or mustard dominated sites inoculation with mycorrhizal fungi may be desirable. Add a ring of large bark mulch or weed mat for each plant if possible. Flat sites may be machine-planted with a transplanter.