ORIGINAL: M.Magis

Based on my experience, you’ll need to modify your plan a bit.

1. You’ll need to wait at least week between mowing and spraying. More if things are still growing slowly in early-mid spring. The plant needs to be actively growing for best results.
2. 1 week for a good kill isn’t nearly long enough. There are things that can help for a faster kill, but I would expect a minimum of 3 weeks. I like the grass completely dead to make working the soil easier. Dead grass and roots break up better than green ones.
3. Just to save tractor fuel, you can either drag or disk buckwheat seed in. I think that stuff will germinate on a rock, so I wouldn’t waste fuel on doing both. Also, buckwheat is primarily used as a soil builder, not so much to kill weeds. Once you mow it and then work the soil again, new weeds come right back. As will more buckwheat unless you mow before it goes to seed. I would suggest you do.
4. Give plenty of time between mowing the buckwheat and planting new seed. It’s very stemmy and it can be hard to incorporate into the soil. I mow it and run the disk over it, then let it sit for a couple of weeks to start to decompose. Then I come back and finish the seed bed with the disc. This also allows many weeds to germinate, which are then killed when I re-worked the dirt for the final time. [ol][/ol]
These are just things that I found work best for me. I’m sure everyone does things a little different with similar results.