Since your seeds were labeled as "North American Natives", it seems like they surely must be natives. Hope so! Usually when you see mixed seeds at a box store, they say "wildflowers" rather than "natives". You may get some plants that you don't like but I think you should go ahead and plant them. You'll undoubtedly get some that you DO like. Orange Butterfly Weed (asclepias tuberosa) is hard to beat. It blooms a long time, attracts butterflies and shows up well from a distance. That one may be in the seed mix that you bought as well as purple coneflowers which I never tire of. Rudbeckia hirta and gaillardias are nice too. Your mix may also contain a lot of plants that won't tolerate hot summers very well. I would love to have a wildflower meadow but have gotten the impression that it's one of those things that's not easy to do successfully, and I've just never tried. I did plant a long mixed shrub/perennial border along one side of our property several years ago and haven't done a very good job at keeping the weeds out. I enjoy it immensely though. I love gardening/wildlife etc. If you're doing it only to save time mowing, you definitely may be disappointed. Otherwise, there's no harm in trying. If your wildflower garden doesn't work out the way you want, you can always collect free seeds from your favorites and start over. Just my opinion but - Since you're in an area of new homes and you may be pressured to have a tidy yard, I think it would make the area look more intentional and attractive to put a section of split rail fence or picket fence across the front to separate it from the rest of your yard. That way your snooty neighbors won't think you're just being lazy about mowing. : ) I would also leave several feet of mowed area between your house and the wildflower patch to make it look neater and so you can easily walk from the front of your house to the back without having to spray yourself with Off every time to keep the ticks and chiggers away. Opinion again - I think you would appreciate having a couple mowed paths through the middle to make it easier to get from one side to the other and so you can see what's growing. Ticks don't hang out in mowed grass nearly as much as knee or waist high areas. Planting shrubs might make it more difficult to maintain. Maybe some others will give you opinions on that. I have trouble with invasive vines, undesirable trees, poke, poison ivy, etc. coming up around my shrubs close to the base where it's hard to remove them. What I think you had in mind is a prairie type area that you can just mow down once a year. Right?

I don't know what type of grass you have growing there but if its native grasses, that can be a good beginning. If not, I would try to put in some little bluestem, blue gama grass and Indian Grass areas. These will grow on a slope. Especially pretty is the little bluestem. The bluestem will make a nice filler for a "meadow" on a slope. I see it growing in the most inhospitable spots on steep rocky slopes and its gorgeous when abused like that, straight up and distinctive like "starched" grass. I would DEFINITELY plant some there. It is so pretty in the fall with the way it catches the light and turns colors. Some very easy, long blooming wildflowers to plant are horsemint, purple winecups, rudbeckia (black eyed susan's) and Oenothera speciosa (Mexican evening primrose). These will re-seed abundantly. The primrose is rugged but I have never started it from seed. Its nearly impossible to get rid of once you have it and will form a sprawling, wide mat of pink. I saw it along the highway yesterday on a slope and it must have covered a 6ft by 6 ft area. Very pretty. Missouri primrose is another good choice. It puts out a long tap root, needs very little water and blooms all season with large yellow blooms and will naturalize well. Another wildflower I love, because it blooms from early spring until well past first frost is Baileya multiradata (Desert Marigold) It is a very neat, very light blue, fuzzy foliaged plant with a huge bouquet of bright yellow flowers all season. One plant can get very wide with hundreds of blooms non stop. I have this naturalized in my yard and get more comments on it that any other plant and its so EASY! All it needs is perfect drainage and a steep slope sounds perfect. It puts out hundreds of seed and will naturalize all over the slope if its happy. A succulent that I find will grow in extremely dry soil is Talinum calycinum (Flame Flower). It reseeds like rosemoss and has magenta colored flowers on very thin stems. Thelosperma will naturalize abundantly. I had one plant two years ago and now they come up everywhere. Blooms all spring, summer and fall. Some are solid yellow and some have red centers in the flowers, which are small but abundant. You can get these seeds from Plants of the Southwest for $3.00/pk. They have a large selection of wildflowers to choose from. As time goes by, you can add to the plants but these are some "easy to germinate and grow" ones to start with. A slope like that allows for perfect drainage which means you can grow lots of dry loving plants that otherwise would fail. A trip outside of city limits is something you could try and look around for wildflowers and native grasses in your area. It can get addictive.

Not trying to get into the wintersow vs. not wintersow debate here but....... The only time it makes sense to wintersow is when you are sowing seeds needing cold stratification and I know some of the ones you listed do not need it. I sowed the Asceplsis incarnata in early August and plan to put them in the ground under mulch all winter. I am winter sowing some native shrub seeds needing a couple months of cold strat. in pots outdoors and three others that are perennials that specifically need it. There are no hard fast rules to this. To each his own. I rather enjoy sowing indoors in winter and have had very good results and it gives me an uplift in winter to do that. I have had good head starts on healthy plants this way and have sowed many SW shrubs, perennials, ornamental grasses, cactus, etc. I always have something indoors in winter I am sowing. I usually start them in October or November in a large sunny S. exposure window and grow them very cool in the coldest dark months sort of in a wait pattern, then let them get warm again in late Feb when the sun comes stronger. I use lights sometimes if necessary but usually they just sit there in the cold. I am not a wintersower to the degree popularized to a hobby level of lots of containers with holes, lids etc craze with every seed I get being done that way. I just use regular pots in the shade under the carport for the seeds specifically needing a cold period. For penstemons its good, they come up when its still very cold. Some seeds needing cold I direct sow. Sometimes I experiment and try all different ways to see what does best with a backup supply to resow in spring. Look up your different varieties and see what they need and go from there. I have sowed seeds as early as October and had established plugs to put into the ground come spring. Other times I put the late summer sown seedlings in the ground in late fall and cover them with leaf mulch and had good well rooted starts that way in spring. Look at nature, she does that all the time with seeds that have fallen. Mostly, make it fun for yourself and do what you want. Save extra seeds for insurance, or try multiple ways and experiment. Do a test in a damp paper towel with a few seeds to see if they sprout in a few days. Often that will tell you want you need to know.

well, on the pereimeter between the lawn and the wooded area I would start amending the soil. Spread grass clippings or manure in this area and also add some leaf litter then wait. If you dont want to wait to long then you could buy some wildflower seeds or plants. If do a search online there are many places that sell native wildflowers and seeds.