Viking Mike, I'm not sure if a friend's house counts but it's worth trying. On the other hand your new home will definitely have a patch in the yard, and I would think that even during this "testing" period, planting there will count for the quest. If you haven't visited the new house yet, go there by typing /home in local chat. EDITED: tried it; planting in new homes DOES count for the quest. It gets logged once the tree is fully grown, so give it a little time.
Hi Viking Mike, You cannot do this quest using friends backyards, its must be your backyard. The new test houses don't count either, so you will either have to move to an area with tree plots or just leave it and wait for the new housing to launch properly, there is no time limit so it doesn't really matter.:) hope that helps.
I still have that quest, cos I never wanted to kill any trees - I went from 1 to 2 last night after planting in my tester yard. It didn't register til the tree was grown. I'll wait for real housing to do the rest though. Maybe when this house disappears the credit for that tree will also disappear?
It does work with the new houses. I got credit for the one I planted, but only after it was full grown, as oscarette said. It takes a little while to get there.