So I've read on another question here of people building netherwart farms in the nether. Now I can understand this since thats the actual place you get the netherwart initially but personally i always build my netherwart-farm in the 'overworld'. I was wondering if there are differences in building this in the nether and overworld (and lets throw in the end while we're at it). Are there any differences with growing speed, best lighting level, adding water, (adding fertalizer(in ftb/techworld)).
Before 1.3.1, Nether Wart could only be grown in the Nether. There are a couple of advantages, though they don't have anything to do with growth speed. Planting large Nether Wart farms in the Overworld might take up precious room, while in the Nether you have lots of room, and since there are no creepers, you don't have to worry about lighting and mobs (except for pigmen) as long as the farm is enclosed.
There is no effect of light or environment on the growth of netherwart. Soulsand is all you need. I do as you do and simply allow my turtles to carve out a large area and then let soul sand span the gap with 2 blocks height in between. I fully light the area, just for convenience and monster spawn avoidance. A ladder that runs down a gap in pit makes for easy access, until the point at which I setup Thaumcraft Golems to do the harvesting for me.
Source: Personal testing... and it's backed up via the minecraftwiki.net entry on netherwart
The duration of each stage is random, with no upper or lower limit, but the average duration is about 3 minutes and 30 seconds. The growth rate is not affected by light or any other environmental factors. Bone meal has no effect on the Nether Wart.