Hello, in regard to transplanting fruit trees outside of Israel, can one resume Orlah from its actual age, when bought from a nursery and transplanted? If so, when does it apply, and one doesn’t it. Also, when growing fruit trees in containers, when one constantly has to uproot them to a larger pot, or to prune the roots, does this also reset the orlah status?

Thank you for your question, In order to continue the tree's Orla status and not restart the count - one must make sure of two things: 1. There must be a hole which is the size of two centimeters in diameter. 2. There must be enough earth connected to the tree that is sufficient for the tree to live in that manner for at least two weeks. (see Hilchot Shmitta: Harav Rimon page 88, comment 34. For more opinions and detail see Peninei Halacha: Kashrut- chapter 2, halacha 7) All the best!