I want to convert my former lawn to lyre-leaf sage and possibly pussytoes and/or blue-eyed grass.

The grass is gone. I need to prep the clay soil and my plan is to break up the soil with a pickaxe and then add composted manure. Then, in spring, plant the wildflower seedlings. It will take me some time to prep the soil.

I have sprayed multiple times with various weed killers at various times over the year for several years. Most of the weeds are spotted spurge, yellow wood sorrel, chickweed, henbit, and several types of lespedeza. It is late October and some weeds are just now sprouting.

So here are my questions:

1. If I prep the soil now and into winter, should I add a pre-emergent herbicide (like Preen) to the soil? And repeat the pre-emergent before I plant? I've never used a pre-emergent.

2. Will the pre-emergent affect the seedlings of the above mentioned plants? That is, can I continue to treat the soil later during the year after planting? I realize that would prevent the seeds from the desired plants from germinating.

3. Does one treatment of pre-emergent prevent the treated seed from ever sprouting? As opposed to newly arrived (birds, wind) seeds.

4. What pre-emergent would you recommend?

5. Is there any other method you would suggest to prevent weeds from growing in my new groundcover?

Zone 7a, East Tennessee

Thanks.