Growing trees indoors -- are trees grown indoors, in unperforated pots, subject to orlah laws?
Note: definitions and laws pertaining to indoor plants and unperforated pots often differ vis-à-vis orlah, terumot and ma'aserot, shemita, and kila'
The Yerushalmi (orla 1,2) states: "A tree planted in an unperforated pot is subject to orlah." Rabbi Yose explains that this is because the roots penetrate through the pot and receive nourishment this way. The Rambam (Hilchot ma'aser sheni 10:8) explains: "A tree planted in an unperforated pot is subject to orlah; while the pot is not 'land' for seeds, it is considered 'land' for trees." The Shulchan Aruch rules likewise (YD 294:26).
Poskim deliberate regarding metal pots, which serve as a complete barrier between the pot and the ground; perhaps according the Yerushalmi's reasoning these would be exempt from orlah (this is not brought down as halacha, though).
While some poskim hold that unperforated pots are subject to orlah mideoraita, others maintain that they are completely exempt. The accepted ruling is that such trees are subject to orlah miderabanan.
