The next time you have withered crops on your land, and you click on a square to remove them, you'll first be given a chance to "instantly unwither" those crops by paying Farm Cash. Similarly, if you've ever let supplies on your Cargo Ships spoil, you can "refresh" those Goods with City Cash as well.
Just as this system works in FarmVille, the more crops or Cargo Ship goods you've allowed to wither/spoil, the more City Cash it will cost to revive them. And actually, it's a fairly expensive number. For example, to unwither 17 crops, I was told the price would be 39 City Cash. That's a fairly huge number on its own, but can you imagine how expensive it would have been had I let even more crops wither? What if there were 50 withered crops? I shutter at the thought.
So why would we bother with reviving crops, if it costs this much? I suppose this would save you from having to wait for crops to grow all over again, should you have needed them for a quest or the like, but at that point, whether or not this high price of revival is really worth it would be up to you.
What do you think? Will you spend City Cash to revive crops or unspoil Cargo Ships supplies? Would you do so if it didn't cost as much? Let us know in the comments.