How will you weed the area after sowing the seeds? You might be better off considering buying plant plugs planting them and covering with mulch to prevent weeds.

There are a couple of issues. Weeds have to be controlled first -- ideally a few rounds of herbicide usage, followed each time by raking off the dead weeds to get more to grow. Then, you have the question of what would best stabilize the hillside and look pretty. Native wildflowers will look pretty but you will need to consider native grasses to really keep the weeds away and to get some deep perennial roots into the hill.

A combination of grasses and wildflowers would give you flowers and teeny tiny little grass seedlings the first year. :)

I would recommend a grass mix like Larner Seeds 'erosion mix' which has fast growing native grasses. A lb will set you back $20 but cover 2000 sq ft. You will need to add some of the longer lived species like purple needlegrass, which would be beautiful in late summer with the purple seedheads and dark green foliage.

I know you didn't mention grasses, just wildflowers, but most wildflower-only seedings fail because of weeds and exotic annual grasses that outcompete the wildflowers the following years.

Good luck -- and let us know how it goes!

CJ

Here is a link that might be useful: Larner Seeds native grasses

I also have a hill with steep sections (7 acres) Right now it all fescue grass, used for hay. I would like to convert it to a native prairie. Do I have to get rid of the fescue grass? I know about the Roundup soy beans, but I am afraid of erosion if I use this method. (Thank you John for the helpful tips on this) Should I also use the plug method, but will the fescue take over the plugs.? Thank you!