A mature plant grown from a Winter Seed may leave untilled soil in its place, when harvested. Any fertilizer used will be lost in this case.
Winter seeds are forage seeds. They take 6 (or 7) days to grow. Since nothing else grows in winter, you can opt to farm nothing but these. Just make sure you make enough seeds for next year.
The crystal berries are the most valuable berries in the game @ 150 apeice, base. They make pretty good jams (350g/4-days) and wines (450g/6-days), the winter roots are good for cooking, the yams can be sold off, and the flowers sold/gifted.
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