Why Are the Leaves on My Indoor Philodendron Turning Black?

Question

Why are the leaves on my indoor philodendron turning black?

Answer 1

How old is the plant?
How long have the leaves been turning black?
Are all the leaves black?
Have you just repotted the plant, or changed it’s environment in any way?
How much light does the plant receive?

Answer 2

Black leaves are usually caused by a fungus, either infecting the roots (most likely) or the leaves. How old is the plant? If you just got it, it should be returned to the store for a refund. How long have the leaves been black, and which ones (old or new, top or bottom) could help determine what the infecting agent is. Just repotted? Could have been a pathogen in the soil. And are the leaves actually black, or dark brown.
Whatever the case, unless it’s a plant infected from the store, or infected soil,
the problem probably lies in the soil being too wet. Philodendron need to have the soil close to dry all the way to the bottom of the pot between waterings. Check out this video about testing soil moisture http://www.youtube.com/watch?v=YBBh0RPPqu0