Gardening Help FAQs

Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

Do you have additional gardening questions? Please contact us. Here's how.

Horticulture Questions and Answers

Why are the leaves on my indoor plant yellowing?

Leaves occasionally turn yellow and drop off indoor plants. Do not be concerned if only a few leaves are affected. But if more than a few leaves start to turn light green or yellow, you may have a problem.

Physical injury to a leaf, while the leaf was forming or after maturity, may cause it to turn yellow and fall off. Other causes of leaf yellowing and leaf dropping are: Dry soil, water-logged soil, overly bright light, too little light, cold, or sudden changes in the environment. As you can see, there are many causes. Any of these factors can stress the plant. The most common response a plant has to stress is to drop some of its leaves. Let's look at some of these causes.

Light is important in order for the plant to maintain healthy green leaves. Light influences the plant's ability to make food and to keep its leaves in good condition. When new leaves appear, old leaves often turn yellow and fall off. This is not unusual because this is how the plant balances available light and the appearance of new leaves. The oldest leaves decline first when there is inadequate food to support the entire plant. This is a normal process.

A damaged root system can also causes a plant's leaves to turn yellow. Root injury may occur due to excessive use of fertilizers, high populations of insects feeding on the root system, lack of water or too much water. Too much water can accumulate if there are no drainage holes in the pot, or if the pot is allowed to stand in a saucer holding the drainage from the last watering. Standing in water can cause the plant's roots to die and the plant itself to yellow and die.

If many leaves of a plant suddenly turn yellow within a day or two, the plant may have been exposed to cold temperatures or to toxic gasses, i.e. gas from a kitchen stove is toxic to some plants. Plants near a window often lose leaves after a sharp cold spell. Plants moved from a store into a home, or even from one room to another, often lose many leaves due to sudden temperature changes. In these cases, a plant will usually recover if the change is not too extreme.

There are no simple answers to the question of why leaves often turn yellow. One must examine the plant's history, environment, watering and soil conditions, in the hope of identifying the primary source of the problem.