1. They can grow inside a cave; as long as there is heaps of light (from jack-o-lanterns) and space for the leaves; adjacent to a water block; sapling planted on dirt.
2. Trees can grow in the nether :-O. You need to clear out any nearby fires; plant the sapling on a dirt block.
The benefit here is if you have trees at the bottom of your mine; you basically can have a close endless supply of wood for your mining operation; especially if you are hunting for diamonds; its nice not to have to go to the Overworld (surface) to chop down trees.
I always wondered how some people planted trees inside caves and somehow made them grow. I just tend to do the same thing these past years of playing Minecraft. Thanks for sharing this dude.
Rollback Post to RevisionRollBack
Bored and don't know what to do sometimes? Want to be able to earn anything on Amazon without spending ANY money? Points2Shop can do just that! Here is a link to my personal referral site if you are really interested. Its an awesome site that I have been using since 2013. Earn points to redeem anything on Amazon. Its free and people of all ages can use it! Things I've earned:
Tony Hawk's Underground for Xbox Original
The Melancholy of Haruhi Suzamiya Sweatband
NBA Spalding Glow in the Dark Basketball
Aftermark U19 Night Vision Webcam
Wolfmother Cosmic Egg Album
10$ iTunes Gift Card (Digital)
If you have any questions, feel free to message me.
the sapling block has a light level of 8 or more, and
there is sufficient space for the tree and its leaves to grow. The shape of the tree varies by tree type, and thus so do the space requirements.
Trees randomly attempt to grow on their own, but this can be hastened by using bonemeal on the sapling.
Since, for example, oak trees can grow to a variety of heights (sometimes 4 blocks, sometimes over 10 blocks with multiple branches that are a pain in the butt to chop down), you can put the sapling in a small area to limit the size of the tree, normally as long as the smallest possible tree can grow in the space available. However, the tree will usually take longer to grow, since many of the growth attempts will fail if there is no room.
I grow trees underground all the time. Just put one torch in the block right next to the sapling and it grows just fine. Same in the nether. Once, a long time ago, I was building a pigman grinder that took loads of trap doors so I put a huge tree farm in the nether. No problems.