A module that makes simple date calculations painless is Date::Simple.

#!/usr/bin/perl
use strict;
use warnings;
use Date::Simple;

my $date = Date::Simple->new('2005-03-01');

for (reverse 1..5) {
    print $date - $_, "\n";
}
[download]

prints:

2005-02-24
2005-02-25
2005-02-26
2005-02-27
2005-02-28

Cris