What exactly are the vernalization requirements for winter grains?

I keep on reading that winter grains need vernalization to grow, but what temperatures are actually necessary for that to happen? I cant find info online. After all, most grains grown in my area are spring grains sown in fall. So what
is required for vernalization to occur?

Each variety of each species has it's own requirements. And it varies depending on the nature of the cold, and the snow, and the soil, and the clouds, etc. Biological systems are not exact. They are at best some type of fuzzy approximation.

Joseph Lofthouse wrote:Each variety of each species has it's own requirements. And it varies depending on the nature of the cold, and the snow, and the soil, and the clouds, etc. Biological systems are not exact. They are at best some type of fuzzy approximation.

Then do they need an actual winter winter or will they be good with my high/low of 68/40? For winter barley, winter wheat, rye, winter oats, etc.

Depends. Each variety, of each species has different requirements....

And there is a vocabulary problem... A lot of grassy grains can be planted in the spring, and they will flower and make seeds the same summer. These are often planted in the fall, and they survive the winter, and flower, but the do not require a real winter. People call them winter grains. It might be more accurate to call them winter-optional grains.

Some varieties of grassy grains require significant/prolonged  cooling. I think of these as obligate-winter grains. A long/cold winter is required.

Some varieties require only a tiny amount of cooling. They will flower and produce grain if planted in early-spring, but not if planted in late-spring or summer.

And some varieties will flower regardless of what the temperatures are when they are planted.

Joseph Lofthouse wrote:
Depends. Each variety, of each species has different requirements....

And there is a vocabulary problem... A lot of grassy grains can be planted in the spring, and they will flower and make seeds the same summer. These are often planted in the fall, and they survive the winter, and flower, but the do not require a real winter. People call them winter grains. It might be more accurate to call them winter-optional grains.

Some varieties of grassy grains require significant/prolonged  cooling. I think of these as obligate-winter grains. A long/cold winter is required.

Some varieties require only a tiny amount of cooling. They will flower and produce grain if planted in early-spring, but not if planted in late-spring or summer.

And some varieties will flower regardless of what the temperatures are when they are planted.

What are some common varieties from each caegory?