the-elder-scrolls-v-skyrim
In Oblivion, Nirnroots were a collectible – there was a finite number of them*, and they did not respawn.
I've been noticing, however, that when I pick Nirnroots in Skyrim, the roots of the plant remain behind. This got me wondering…
Do Nirnroots regrow in Skyrim?
What about the Crimson Nirnroots of Blackreach?
*discounting the respawning food-nirnroot in Frostcrag Spire
Yes, there will be Nirnroots in Skyrim:
This image is from the G4TV Skyrim demo. You can also see Nirnroot in the Skyrim Trailer.
You can find information about its alchemical properties, location, quests and lore on the Elder Scrolls Wiki Nirnroot page.
Skyrim creates auto saves that are usable from the load menu by default at the following times:
However, these are created on a rolling system which by default only allows for three auto-saves to be kept. Once there are more than three autosaves (including across characters), the oldest one will be overwritten on the next save.
In addition to this, whenever you encounter a loading screen a temporary non loadable save is made that serves as your respawn point if killed. There are no story replay style saves (as seen in GTA V, for example) in Skyrim, nor to my knowledge ever have there been.
Manual saves can be made at any time, and if you are playing on PC then there is a mod available that adds new autosave options.
Best Answer
Nirnroot does indeed grow back and can also be bought from Alchemy stores. It is a lot less rare than in Oblivion. With regards to the Crimson Nirnroots, I am not sure, because I haven't come across them yet. However, I believe they would re-spawn too. (All alchemy Ingredients I have seen so far do.)
EDIT:
I just wanted to confirm that crimson nirnroots do indeed regrow after 15 in game days, as seen here.
A quick warning: do not pick to many crimson Nirnroots before starting the quest, as it has been reported that this will cause negative progress through the quest.