Cake's Fully Automatic Mushroom Farm - 2 of 2
Channel: The Grinning Viking
Date: 2012-12-14

Part one is here
http://www.youtube.com/watch?v=TKCbwjnVarM

There are some links to some really interesting mushroom farms and a redstone tutorial linked there as well. This page is filled with mushroom facts! :)

Some interesting facts from my testing:

Mushrooms can grow up to two away on a clear plain, though only rarely

Mushrooms can grow onto any non-transparent full blocks, including chests, furnaces, and soul sand. Grow rate is equal on all possible blocks.

Mushroom grow rate decreases with increased light, and they cannot grow into squares 1 away from torches, or 2 away from fire, glowstone, jack-o-lanterns, or squares touched by sunlight. 

Mushrooms will NOT grow into any square that would be too bright during the daytime: even if you try to trick them by putting them under a canopy of one thick leaves or other semi transparent blocks. (It was worth a shot!)

Mushroom grow rate is determined by the parent mushroom. This means that a mushroom placed in a dark enclosure where it can grow diagonally into a lit square - provided that square is at least 2 away from any nearby torches - will have maximum growth rate.

Mushroom can grow up and down diagonally, and while one row growing horizontally into a square is faster than one growing diagonally - TWO rows growing diagonally into a square is faster than one growing horizontally and also allow the parent mushrooms to be kept separated from any light sources by hiding them behind diagonal walls.

Mushrooms will remain planted in bright light until the square next to them changes. Nice for decorating! (And using redstone wiring to do it makes this farm possible :) )

The sign/fire trick is the only way I have found to produce variable lighting that mushrooms will grow into.

I've already figured out a quick / easy way to improve this once pistons come out without redoing a lot of work. Watch for that! :)

Thanks again for your time, remember to thumbs up and subscribe if you like!