Border blocks are tricky :/
I don't know of a way to change the size of border blocks off the top of my head, so if all of your trees are 3x3 (like the Viridian Forest trees), then you'll have to place enough of your trees surrounding your map so that the border block isn't showing.
There may be a way to resize the border block to 3x3, but you'd have to look into a solution. Sorry about that. Btw, I like your profile pic ^_^ looking forward to that movie.
I don't know of a way to change the size of border blocks off the top of my head, so if all of your trees are 3x3 (like the Viridian Forest trees), then you'll have to place enough of your trees surrounding your map so that the border block isn't showing.
There may be a way to resize the border block to 3x3, but you'd have to look into a solution. Sorry about that. Btw, I like your profile pic ^_^ looking forward to that movie.