Kathy, oooh buckwheat is very tender. You must be really careful with it, it will germinate in no time once the soil warms up. (just only a few days). Buckwheat comes into flower also really fast, so you have lots of time on your hands here. Kathy, I think that from seed sowing to flowering is something so short, like maybe 6-8 weeks, you can have a continual crop of buckwheat right up until frost kill.
What you should do, girl, is save a good part of the seed and sow it every few weeks, like you do with the lettuces and crops that you want a full summertime fresh harvest of. So, do that. It will help to prolong the buckwheat growing season. Come the fall Kathy, when the buckwheat seeds are maturing, pick the bunches. You will see them growing in massive clusters, just grab them and put them into a great garbage pail or brown bags, dry the seeds out. You will know when the seeds are fully mature because they will be brown as the dickens. You can also begin to gather the seed when the seeds are not completely brown. As with many annuals, the seeds can be picked long before they "look" fully mature (brown), they will ripen on their own. You will see all summer long the brown seeds that will be on the plants, pick them, I encourage that strongly.
But remember too, as with many many annuals, those plants that you have, you will never in a million years get all the seeds. You will have buckwheat on your property til the end of time itself. Once you got it you got it. Where I originally planted buckwheat it grows all on its own now. I don't even sow that area. I saved the seed and am starting new buckwheat patches all over my property. It is a most beautiful plant and the flowers are born in enormous clusters that are something for the eye to behold. You are gonna have some fun this year, Kathy, growing your beloved buckwheat, and think of that lovely honey that will go along with it, it will be a combination of buckwheat and wildflower I am sure, and it will be good. If you have any more questions about buckwheat sowing, let me know. Oh by the way, you don't have to cover the seed, it will germinate on its own. If you have fears that the birds may get so much of it, brush some dirt over it to it is kind of hidden, but don't make that dirt covering deep, having light to germinate really helps it along. Have the best of this beautiful day. Cindi