Blues have a tough schedule ahead and Gardner feels more players are needed to ease the burden on the current group.
Blues face difficult Barclays Premier League games against Everton, Manchester United and Arsenal in Christmas week followed by a derby at Aston Villa and a two-legged Carling Cup semi-final in January.
Gardner said in the Birmingham Mail: "We do need bodies. We need players in, end of story.
"We`ve got a brilliant set of lads, but we have a lot of games coming up now.
"After Christmas people may well be fatigued and hopefully we will be able to bring in one or two new faces and kick on from there."