Question: My splitleaf philodendron’s leaves aren’t splitting any more. What causes it to revert?
Answer: The vining type of splitleaf philodendron will have the cut leaves as long as their stems are growing upward. As soon as they reach the top of their pole and start hanging downward, the new leaves will revert to being full and rounded. Supply a taller pole, or trim them back to the top of the old pole. Be sure, too, that the plant receives adequate light.