Yellowing Leaves

Several issues can cause yellowing leaves, such as giving it water that's too cold, not offering enough sunlight, or exposing the plant to too much bright light. If the older leaves are yellowing, then you may be under-watering the plant. If the younger bottom sets of leaves turn yellow, you may be overwatering the plant. In most cases, adjust these factors to see your plant rebound.

If you give plant food to your philodendron, be careful to water the soil first, add a water-diluted fertilizer solution, and then water the plant again. These extra steps ensure the roots do not get burned by the chemicals in the fertilizer, which can cause yellowing.

Yellowing and Rotting Smell

If your plant's leaves turn yellow very quickly, it can be a sign of root rot. If you catch it quickly, you might be able to save the plant. Smell the soil for a rotting odor or dig up the root to inspect its health. In most cases, cut away the black, mushy pieces of rotting root and replant the white or yellow portions of roots in a clean container with fresh soil.

Yellow Splotches or Patterning on Leaves

If you notice small yellow lesions or patterns on your plant's leaves, it can be a sign of the mosaic virus. You may be able to get rid of the virus by helping the plant defend itself: If the temperature is still warm, bring the plant outside for some indirect, natural light. Keep the infected plant at least 2-feet away from other plants. Remove the badly affected leaves. Hose down the rest of the leaves, removing any dust on the surface of the leaves. Apply a diluted nitrogen-rich fertilizer to the soil, to help the plant grow back stronger.

Browning Leaves

If your plant develops browning leaf edges, you may be shocking your plants with water that's too cold. Also, if your plant's leaves start to get brown and mushy, you are likely overwatering. Brown leaf edges that start to curl indicate the plant needs more water and less sun. Make adjustments accordingly.

Browning leaf tips with yellow halos can indicate that your plant needs more humidity. You can mist the plant's leaves or place the plant container atop a tray of pebbles filled with water to raise the humidity. Don't submerge the plant base; keep it right above the waterline.