It can be challenging to seed wildflowers at the same time your sowing your native grass mixes. Weeding your grass planting can be very difficult unless you have an experienced eye to distinguish between weeds and desirable wildflowers.
Western Trails Mix: Be sure to select wildflowers that germinate in hot weather and don't require winter cold to condition the flower seeds to germinate. Mix them into the sand/grass seed bucket at sowing time. If a wider range of wildflower types is desired for your Western Trails Mix, you can leave long rectangular bands or irregularly shaped areas in the grass unsown with grass seed. This allows you to go back in the fall to sow wildflower mixes that require winterizing ("cold stratification").
High Mountain Mix: Be sure to select mountain wildflowers that can germinate the following spring after getting the winter moist cold needed to overcome seed germination inhibitors. Mix them into the sand/grass seed bucket at sowing time.
Alternately, for either grass seed mixture, you can transplant potted wildflowers into the established warm or cool season grass meadows, choosing flower species that are good re-seeders to act as mother plants that will scatter seed naturally and fill into the grass over time.