This is a userpage about Sugar Cane's behavior. Nothing on this page has been written without being tested before.
Also, most of the informations here can also be found on the Sugar Cane page. (except about the underwater part)
 Basic behavior
To fully understand how sugar canes work, it's important to know how to use it.
There's 2 conditions in order to be able to plant Sugar cane.
- You can only plant on untilled dirt blocks.
- There must be a water block right next to the dirt block.
There's no light needed ! Thus, Sugar canes can even grow in the darkest caves.
In order to grow, canes need to fulfill the planting conditions, and also need an empty block above.
When fully grown, a Sugar cane will be 3 blocks high and can't grow further naturally. However, you can add extra blocks above, by hand, exactly as cacti. I'll call this, "Artificial growth" since the game do not make the differences between natural and artificial growth. It will only notices that an extra block has appeared. Then it will determine if the growing conditions are still fulfilled and if not, the sugar cane collapses.
It blocks water and lava.
It is used to craft Paper (which is used to craft Books, in order to finally craft bookshelves.)
It is also used to craft Sugar.
It's "projectile-proof" (though it seems it has yet to be tested against Ghast's fireballs. However farming sugar cane in the Nether may be quite complicated due to the lack of water) EDIT : It has been tested : The cane acts like a barrier, but the fireball will destroy it just like most blocks.
 Underwater behavior
Underwater, Sugar canes can be planted on any surface. This may be due to the fact that the game will just see a switch between "Water block" and "Something block", thus it would "forget" the planting condition at the moment. However, as there would be a water block right above, the cane won't grow naturally.
In order to grow, Sugar canes must respect the same conditions than normally (Dirt + Water)
 Natural growth
Since Sugar canes can't break through other blocks while growing, there's high chances for it to not grow naturally because of the water above. If, somehow, the block above is free and the cane is not full-grown, then a Sugar cane block will eventually appear on the top.
One example where the block above is easily free is when the cane actually grow out of the water.
 Artificial growth
Ironically, this happens more often, since natural growth are really rare.
Artificial growth is performed by placing a Sugar cane block above another one.
- Used to make bookshelves which can interact with enchantment tables to cause higher enchantments.