So I made a massive tree farm for each type of tree. The oak farm is working just fine, but the other trees function a little differently. The other three types require that you put two blocks of space in between each sapling to be able to grow. Also, the height has to be at least 7 blocks of free space above it.
I spaced each sapling out with 2 blocks in between each sapling, like so:
Each block of stone represents a block of glowstone, and the sapling is on grass that is at the same level as the glowstone. There is no ceiling so all trees have direct access to the sunlight. I then let them grow for a real life day. I came back to see that about half of them had grown, and others still had direct sunlight (as well as the glowstone light and no block obstructing it) but weren't growing. I then used 8 stacks of 64 bone meal on one such sapling with no luck. I repeated that on another sapling. Is this a bug or am I missing something?
The saplings that won't grow have leaves blocking the sun on each side of it, but not directly above. For example:
In addition, I can clear a 1 block radius around the sapling and it still will not grow.
Even more, I have a sapling with a single leaf in the corner of this 2 block radius and it will not grow.
In case it needs saying, the leaves are not at ground level but rather the 3rd-6th block above ground. Strangely, some of the saplings had cases exactly like these but did end up growing. I know this because I have a large field of these and there are many dense clumps that grew, meaning that leaves clearly overlapped part of the two block radius.
Again, there is a clear path, no ceiling, plenty of light, and plenty of bone meal. I have also tried breaking the sapling and replanting it. This issue happens for all types besides oak. A lot of details, I know, but I don't want suggestions that I've already tried so I wanted to be very concise.
I got these numbers from the Minecraft Explorer app. It doesn't say what the requirments are for jungle trees, but i suspect its 1x1 horizontal, and maybe 15 above. The shortest jungle tree are 9 blocks high and the tallest (the 2x2 ones) are 32 blocks high.
If anyone knows the exact numbers for jungle trees please correct me.
Not sure why you're having a problem with them growing like that.. I have a tree farm and there's 2 blocks of space between each tree and they grow just fine.. I use it for birch and spruce.. For oak I actually have a different setup as those can be grown right next to each other. However, I've never tried bone mealing those ones... When I have attempted bone meal closely spaced trees (the oak ones for example) I have noticed that it takes a lot more then normal.. But letting them grow on their own has always worked for me.
All I do for all tree farms is just place them all next to each other. Like a mass formation. Its not good to start off with, but they will grow together and you don't have to fight through all of the trees' leaves.