Why are your houseplant’s leaves turning yellow?

Start with the pattern

An occasional older, lower leaf can yellow as a plant matures. Several leaves changing at once, or yellowing that keeps spreading, deserves a closer check.

Yellowing can accompany too much water, too little water, unsuitable light or temperature changes. The same visible symptom can have different causes.

Sources: Leaf damage on houseplants.

Work through this context checklist

1. Pattern: Is it one older leaf, the newest growth, or leaves throughout the plant? Note when it began and whether it is progressing.
2. Moisture: Feel the potting mix below the surface and check for water sitting in the outer pot. Avoid adding water solely because a leaf looks unhappy.
3. Light and temperature: Has the plant moved, started receiving strong direct sun, or been exposed to a heater or cold draft?
4. Other signs: Look over stems and both sides of leaves for insects, webbing, spots or other changes.

Sources: Yellowing Leaves on Indoor Plants; How to help a poorly houseplant.

Choose a next step that fits what you found

Compare your observations with the care requirements for the plant. If water has collected in the outer pot, empty it. If you suspect a pest problem, separate the plant from the collection while you investigate.

Do not assume every yellow leaf needs fertilizer or a pesticide. Problems can come from growing conditions rather than an insect or disease. Identify the likely cause before choosing a treatment.

Sources: How to help a poorly houseplant; Yellowing Leaves on Indoor Plants.

Keep a clear record for your next check

1. Photograph the whole plant and the affected areas in good light.
2. Write down when yellowing started, the last watering, and any recent move, repotting or feeding.
3. Record what you change and the date. At the next check, compare the plant with your earlier photo.
4. If the cause remains unclear or the decline continues, take those observations to a local nursery or extension service.

A useful note might read: “Two lower leaves yellow since Monday; mix still damp; moved away from the window last week.” That gives a person helping you much more to work with than “yellow leaves.”