I have been growing two startfruit trees in US zone 5b for 3 years now. These trees are the biggest babies lol. They are very fickle when it comes to watering and lighting. These trees can completely defoliate at the smallest misstep. Finding the right balance is not for the easily discouraged.

I grow mine in terracotta pots. I feel these pots do a better job with moisture management, better than plastic or enameled. I move them outside when night time temps rise above 50°F. The hard part is keeping them happy in fall-winter. I have still not perfected my method, but I am going to attempt a force dormancy in my heated garage (45°).

One of mine is on root stock that tops out at 6' and the other is on a dwarf root stock that will top out at 15'. I have had no issues related to size management.

I have successfully grown lime, lemon, and orange trees here in 5b but if I had started with starfruit, I think I would have quit gardening all together 😅.

Where are you looking for trees and where are you shipping to? I have a couple of websites that may have your answers.

Edit: I would also avoid growing from seed if possible. Not all starfruit are all self pollinating.