Posh had to survive a storm to chalk up their second away win of the week as Pools hit the woodwork three times in a game that could have gone either way.
Dean Keates curled home a free-kick to give Peterborough the lead before the home side hit back when Andy Monkhouse's low right-wing corner crept in.
George Boyd slotted home the winner after Chris Whelpdale's shot was deflected into his path.
"It was a fantastic win for us, possibly the most important of the season," Ferguson said. "It was a horrible game and a difficult one for us. But we did well in the first half-hour and deserved to be in front.
"Then they got a break to come back into the game, but in the second half we rolled our sleeves up and got stuck in after we had taken the lead again. It was a real test of character, but we dug in and got what we deserved. We even got a bit of luck late on when they hit the bar again."