You can keep the Bios Urn and tree in the Bios Incube for as long as you want.
Technically, and according to our tests, a tree pine will grow enough to be transplanted to the forest in about 12-14 months. But as I say, you can transplant the tree earlier or even later.
And also, it depends on the seed you choose to plant. But the important thing, as I see it, is that if you want to keep the tree inside the Bios Incube for 10 years, you can perfectly do it. The only thing is that the tree will stop growing until you transplant it. Because trees only grow their size according to the soil volume.