Leaves on plants turn yellow before they are shed. Diagnosing the cause of yellowing leaves on a house plant is difficult, as there are hundreds of different types, each with different requirements. There are a number of common causes of yellow leaves, and finding out which one is affecting your plants is a matter of analyzing the conditions in which it is growing. For example, if a house plant is happy growing in one location, it is often difficult to move the plant without stressing it and causing it to shed some leaves.
Yellow leaves on house plants are often a sign that they are being overwatered or have become waterlogged. Water your house plant when the surface of the soil is dry. But do not leave it standing in a saucer, as this will cause the roots to become waterlogged and damage the plant. Make sure the plant's pot has drainage holes and allow it to drain fully after watering.
If a plant has a lot of yellow leaves, check the soil: water if it is dry to the depth of 1 inch. Chronically underwatered plants tend to be small, look weak and have leaves with yellowed margins. Additionally, if soil is left in a pot for a few years, the soil loses its structure and ability to hold water. Consider repotting older plants in a slightly larger pot with fresh potting mixture.
Many house plants are tropical in origin and do not tolerate cold temperatures. If your house plant has developed yellow leaves during the fall or winter, move it to a warmer spot. A south- or west-facing window is often the warmest place in a house for a potted plant. In winter move plants with yellow leaves away from outside doors and cold drafts. Never place plants next to or above radiators, as the hot, dry air will cause them to shed leaves and even die.
Different house plants require different levels of light. If your plant has yellow patches on some leaves, this is a sign that it is suffering from sunburn and needs to be moved out of direct sunshine. On the other hand, pale or yellowish leaves may be a sign that your house plant needs more light and should be moved to a brighter spot. If you have recently moved a house plant and it has turned yellow, put the plant back in its original spot.
Lack of Nutrients
House plants kept in pots with limited soil need to be fertilized regularly. If all the leaves on your house plant look pale and yellowish, this is a sign that the plant is short of nutrients. Use a liquid plant fertilizer enriched with micronutrients, such as iron and magnesium, every two weeks until the yellowing disappears, and then fertilize every month.
Plants naturally shed old leaves and these will turn yellow before they drop. Some species, such as jade plants, turn yellow and even die if treated with leaf shine products.