Instructions
Locate the Bean Seller. Follow Zora's River upstream until you encounter a short man in blue pants carrying a brown sack. The Bean Seller is located next to a small bean field near the source of the river in the northeastern part of the map.
Speak to the Bean Seller by approaching him and pressing "A" on your controller to begin the dialogue. Select the magic bean from the Bean Seller's shop inventory and press "A" to purchase the bean. The seller will explain how to plant beans in soft soil patches throughout Hyrule after you purchase your first bean.
Speak to the Bean Seller again to purchase additional beans. Players can purchase up to 10 beans from the Bean Seller, after which he will refuse to sell any more. The Bean Seller increases the price of the next bean by 10 rupees each time you purchase a magic bean, citing the item's popularity as the reason for the price increase.