Philodendron Leaves Turning Yellow

Introduction

A common issue with philodendrons is leaves turning yellow, and brown, as well as falling off.

Here are the reasons your philodendron leaves are turning yellow or browning:

Overwatering: philodendrons hate to sit in waterlogged soil, only water them if the top half of soil is wet. They get root rot easily and this can cause yellowing. If yours is sat in wet soil, then take it out and let it dry out, and repot in dry soil.
Underwatering: if the plant does not get enough water it’s leaves can crisp up and yellow, check the soil and if it is really dry then check it each week (but only water it if the top half of soil is dry).
Lack of humidity: most philodendrons like humidity of 50-60% or even more, leaves can crisp up if in dry air for too long. The best bet is to get a humidity meter and keep an eye on it, especially in the drier months.
Pests: check the plant each time you water it, including under the leaves, stem and soil. You want to treat it before an infestation takes hold.
It is too big for it’s current pot: this happens with crawling philodendrons like gloriosums especially. If they are too big for their current pot an older leaf may die off as new growth comes. Solution: pot it up a size.
Leaf burn from exposure to too much direct sunlight: move it back or off to the side of the window away from direct sun, but with plenty of indirect sunlight