This plant can be super vigorous. Personally I'd just try to plant the stem deep so it stands a chance of coming back up from the underground portion when frozen to the ground.

I have several clerodendrums including Splendens planted deep as a precaution. Mine got some damage last year while in full bloom. It quickly leafed back out and was back in bloom in no time and I noticed it started suckering like crazy from the underground stem I layed down.

I plant even my angels trumpets very deep just in case the above ground portions ever get badly damaged for whatever reason. I planted my blue sky vine with three feet of the stem underground and now it sends up new suckers galore from that underground stem whenever the top portion is stressed for whatever reason.

My neighbors lawn people for instance hacked it back brutally and it responded with tons of new rampant growth from all along that underground stem I layed down for it. But Splendens is a short day bloomer for me so I'm not sure it's really worth growing if it just gets cut back by frost in your area everytime it comes into bloom in winter.

Upon closer inspection, I found out that it is Harlequin Glorybower (C. trichotomum), not C. splendens. I only had a 3-inch piece of root on what I dug up, with a shoot on top, so I put it into a pot and am hoping for the best. It evidently does not like to be transplanted, because all the leaves quickly wilted, but one at the very tip top seems to be doing o.k., so I have hope. I guess no plant likes just being jerked up out of the ground, right? Anyway, it has pretty white flowers and very showy red and blue seed pods in the winter. Seems it's pretty common up here, but I've never seen it, just the C. bungei, which I'm not too crazy about.

I had a Fireworks clerodendrum in SW Florida, but it never bloomed.