Rockefeller Center has a new centerpiece — all 37 feet and 50,000 flowers of it.

It’s Jeff Koons’ “Split-Rocker,” a mammoth topiary the Public Art Fund unveiled Wednesday at 30 Rock, right where the Christmas tree usually stands.

Inspired by his son’s rocking horse and a toy dinosaur, Koons melded the two heads into one Picasso-like asymmetrical whole, with “handles” protruding from each side. Live flowers — begonias, geraniums, petunias and more — color the sculpture, watered by an irrigation system within its stainless-steel armature.

If you’re feeling a sense of déjà vu, well, you should: Koons’ massive, flowery “Puppy” was unleashed on Rock Center 14 summers ago.

But “Split-Rocker” is just the tip of Koons’ iceberg: His first New York museum retrospective opens Friday at the Whitney Museum of Art — five floors of the 59-year-old artist’s patented blend of innocence and erotica.

Prepare to be amazed.