I have been harvesting ingredients a lot today and was wondering.

Yes but it take 30 in game days IIRC.

Yes, they do.

But it will take a while to grow back.

Thanks

Also, keep in mind that the respawn timer is reset each time you enter a cell. So if your cell is set to respawn every 30 days and you enter that cell 29 days later, this will reset the timer back to 0. It will now be 59 days before anything respawns. You have to stay out of that cell for the entire 30 days duration.