I believe it is a Korean novel/manhwa. The main character is female and lives in "medieval" world. She is the daughter of nobles and learns magic from a famous magician along with 2 boys, one of whom is from a knight's family. I don't remember if she reincarnated or not.
She has a possibly unique magic power that allows her to grow plants, which I believe she uses to make potions. After time skip her parents die in an "accident", and her brother, the heir, leaves the house secretly because of debt. The main character meets a duke (maybe) that gives her money in exchange for her magic power to make tree/plants in a desert.