I cut mine back a little more than half mid-May and again early June. The plant will flower a little later 12-18" shorter.

Thanks for relaying this real world experience mollydog. And so as far as you can tell floriferousness does not suffer?

Flowers maybe a tad smaller, but not signicantly because the plant becomes bushier.

I pinch my Phlox David and Phlox Niki back in mid June and possibly again in early July to control height. The result is shorter plants with somewhat smaller, but more, bloom clusters. I am very happy with the results. More smaller bloom clusters on shorter plants more than make up for the fewer bigger flower heads collapsing to the ground.

Thanks for that gazania. I will do this next late May.

aha, the Chelsea Chop - yep, I do this with asters and helenium as well as phlox - works a treat.

I do not pinch back my phlox because the deer do a thorough job of it. This year one area his been eaten at least twice and are very short but they are still setting blooms.