The visitors started off with plenty of neat passing work but it was Boston who carved out the first clear chance, Noel Whelan chipping just wide after great build up work down the middle by Simon Rusk.
That moment apart most of the first 25 minutes saw both sides seemingly content to battle for midfield new supremacy.
However on 26 minutes Peterborough got their first serious effort on target when a 20-yard free-kick by Adam Miller was pushed over by Nathan Abbey.
Boston tried to find a way round the visitors defence but crosses from Brad Maylett and Julian Joachim proved too strong for their colleagues to meet.
Back at the other end, a 35th minute corner by Paul Carden found Chris Plummer but his header flew too high.
Just before the break Posh went close again when, from another Carden corner, Mark Arber's header was cleared from close to his own line by Ross.
Boston went close to breaking the deadlock on 50 minutes when Mark Greaves got his head to a Ross free-kick but the ball flashed inches over Lee Harrison's bar.
Back at the other end Posh again forced Abbey into saving action when holding an Arber header from another Carden corner.
Boston took the lead on 63 minutes with a twice-taken penalty after Sean St. Ledger tripped Lee Canoville. Harrison saved Whelan's first spot-kick but the referee deemed him to have moved off his line.
Ross took responsibility for the re-take and fired in.
Boston went close again in the 74th minute when a Ross shot was held by Harrison.
In response Peterborough exerted some pressure on the hosts and had long-range efforts from St. Ledger and Miller which flew high over the home bar.
Just before full-time Joachim and substitute Lawrie Dudfield worked a neat move that the latter fired wide of the far post.