When do you plan on harvesting the potatoes? My potatoes were all harvested in June on my 6a garden so you must have planted pretty late to still have then in the ground. Buckwheat takes about 6 weeks IIRC to go from seed to bloom and that is in the heat of summer so with waning daylight in the fall it may take a little longer. That being said, garlic can be planted pretty late as long as the ground is not frozen*.

* Zeedman, one of the serious garlic growers and collectors here on GW, tells of planting garlic into frozen ground using a drill and auger bit to open the planting holes so I guess that would give you well into December as long as the snow wasn't piling up.

What does NS stand for in your location (NS zone 6a)?

Thanks for your thoughts. My concern was more about pests and diseases and that mysterious chemistry that goes on in the soil that makes some crops better or worse for following crops. I see now that my question was confusing. As for buckwheat, if it only grows 10" before I till it that's okay, it will serve a purpose...NS stands for Nova Scotia; we have a long cool season and mild-ish winters, something like Scotland. Potato harvest in June! Some potato varieties grow close to frost time here. Shows the limitations of going by growing zones.