'Pure white’ corns grow in a very cold land in Hokkaido in northern Japan.
1. Should quote marks be removed from 'Pure white'?
2. Is 'a very cold land' correctly phrased?
3. Would it be better if I change the italicised part to "in Hokkaido, northern Japan"?
If you were talking about numerous varieties, then "corns" might be OK. (Like "fishes" is sometime OK.)