[fritterdonut]

When left alone, Nether Wart planted in Soul Sand will grow through three distinct stages. Nether Wart does not react to bonemeal. Nether Wart only grows in the Nether on Soul Sand. Nether Wart has a 0.00407% chance of growing to the next stage every 1/20th of a second in Minecraft. This doesn't seem like much but given a few minutes you should notice its growth. [1]

So, 100/0.00407 = 24570.024570024570024570024570025
24570.024570024570024570024570025/20 = 1228.5012285012285012285012285012
1228.5012285012285012285012285012/60 = 20.47502047502047502047502047502

So it should take ~20.475 minutes on average for Netherwart to advance one growth stage.

I AFK'd in the nether with a netherwart for an hour and a half, and it didn't grow at all. (And yes, it was very well lit)
Does Netherwart grow properly in SMP?

[Kress91]

Nope.

[Cheez99]

You found some? I could never find any. Guys, if you find netherwart, replant it. It can't grow anywhere else, anyway.

[Shampoo_Lord]

I promise you that it does grow; patience is key to the cultivation of netherwart. I waited HOURS to see any kind of harvest.

[Lineant]

Takes about 2-3 hours for them to grow.
I'm starting to get upset that people are selling them for cheap now. :/

[Shampoo_Lord]

Takes about 2-3 hours for them to grow.
I'm starting to get upset that people are selling them for cheap now. :/

Right!?

[fritterdonut]

I have successfully grown my netherwart now.

Required about 2-3 hours of AFK in the nether though, so it's a risky proposition.

[Abahab]

*Continues banging head against wall waiting for nether wart to finish growing...

[XsyntaXerrorX]

mine was growing just fine and then Cannabin0l dug his way into my hidden farm, killed me and ripped them out of the ground...

[ramien123]

Cannib, why would you do such a terrible thing? It's acts like these that turn people against you.