We have 2 rescue christmas trees in our garden. One my dad brought here from the tip and the other was rolling around the high street one year after christmas, I should think one has been in 6 years and the other about 4 years. Initially tho they just sat there, didn't grow at all, but the last couple of years have grown nicely. (we use the artificial tree indoors lol)
We just dug a hole a in they went, take your chance type effort!
Just been out and taken a pic 4u, doing well!