What causes Heartleaf Philodendron leaves to not separate from their shoots?
I have several small Heartleaf Philodendrons that have been growing for a couple of years. For the most part, they seem healthy, but oftentimes new leaves have difficulty fully unfolding from the little shoots they grow from. The stay stuck in the outer protective leaf and don't open up, and either dry out and die or form stunted, misshapen leaves when they finally pull themselves free. You can see this in the picture I've uploaded, which shows a stunted leaf and a leaf that has not managed to unfold itself from the shoot it grew in.
Does anyone know what might cause this problem? I admit that I don't water them as regularly as I should, but it's not all the tendrils that do this.