I am interested to grow Chinese cinnamon yam and gobo and wasabi. Since we consume the roots how do we regrow them again every year since they are perennial?
Cinnamon Yam has to be allowed to grow until it forms tiny tubers in the leaf axils. Then the parent plant can be harvested and the little tubers planted for subsequent years' harvest.
Gobo is a biennial and if you do not want to buy new seed, let one plant over-winter. It will flower and die the next year, giving you lots of more seed to start next year's crop. To cover the second year, buy twice as much seed as you need for one year and keep the second batch for the next year. After that you will have enough of your own seed.
Wasabi will grow from any bit of root that has an eye on it. The easiest way is to buy as many plants as you think you need per year and when you harvest the plant, cut off the top with a 1cm slice of root, let the top callus over, over night and replant and eat the rest.