Experts and BHG readers answer.
Mulch for winter protection?
Shredded leaves may compress too much, and I'd be worried that the creeping phlox (P. stolonifera) might rot underneath. You might try straw mulch, which would stay lighter and perhaps fluffier, preventing rot. Also, make sure your creeping phlox go into winter with plenty of soil moisture before the ground freezes; creeping phlox stresses in dry conditions.