I've created a wooden tower with wood platform bridges to find floating islands. As a result, I need a lot of wood and my supply is running low.
I had actually planned for this and created a tree farm, but it isn't very productive. I set it up as follows, which repeats across a leveled "field" wide enough for forty saplings total. I know the torches aren't necessary — I used them as a ruler when laying everything out and left some in for looks.
Unfortunately, this seems to produce about one tree per game week or less, which is painfully slow compared to my needs. My suspicion is that the tall grass which grows constantly is blocking the growth of trees, which I know need some room around them. I try to "weed" the farm pretty regularly, but grass starts regrowing by the time I get from one end to the other.
What can I do differently to make my tree farm more efficient?