This is the first year for a cover crop so I choose Buckwheat , the reason was because the fast growing crop. The residue decomposes quickly when dug into your soil and adds needed organic matter.If you plant about 5 or 6 weeks before the first frost, you won’t have to turn it in. Buckwheat is frost sensitive and will be killed.To prevent reseeding buckwheat must be turned under or cut within 10 days of flowering to prevent reseeding. Buckwheat sets seed quickly. Unless you want to be pulling up volunteers (which are easy to pull up by the way) you want to turn under the buckwheat no more than 10 days after flowering. It sets seed very quickly and is doing so while those beautiful white flowers are blooming. So about 35 days after seeding turn it under.