Question:
Is it permitted to plant hadassim, aravot, or an etrog that were used for the mitzvah of Sukkot, and then allow them to grow for future use or for ordinary purposes?

Answer:
Yes, it is permitted. After the conclusion of Sukkot, all four species become permissible for benefit. Planting them and deriving benefit—whether for mundane purposes or for future years—is no different from any other permitted use.

Sources:

See Michaber 665:1; Rebbe Yochanon in Sukkah 46b; See Admur 649:20