Yellow leaves are a signal, not a diagnosis. The most common cause is too much water. Low light, natural aging, hunger, too much sun, and pests also turn leaves yellow. Each one leaves a different pattern, so the pattern tells you where to look.
This guide shows how to read the pattern, how to confirm the cause, and what to do next.
Start with three questions
Answer these before you change anything.
Which leaves are yellow? Old leaves at the bottom, new leaves at the top, or leaves all over the plant?
What does the yellow look like? The whole leaf, the edges only, the space between the veins, or small spots?
What does the soil feel like? Push a finger two inches into the pot. Is it soaked, damp, or dry?
Keep the answers in mind as you read the causes below.
Overwatering
This is the first suspect when lower leaves turn yellow and the soil stays wet. Roots need air. Soggy soil fills the gaps with water, and the roots start to rot. Rotted roots cannot move water to the leaves, so the leaves yellow and drop.
Other signs include soil that stays wet for more than a week or two, a sour smell from the pot, a soft stem base, and fungus gnats around the surface. Gnats are a clue that the topsoil stays wet too long. The plan for them is in how to get rid of fungus gnats in houseplants.
Stop watering until the soil dries to the depth that suits the plant. If the roots are brown and mushy, repot into fresh mix and cut off the rotted parts. How to repot a houseplant step by step covers the process. Winter makes this problem worse because plants drink less. See how often to water houseplants in winter for a better routine.
Underwatering
A plant that goes dry for too long also yellows. The leaves often look dry and crisp as well. They may curl, and the soil pulls away from the edge of the pot.
Wet and dry plants can droop and yellow in a similar way. Check the soil to tell them apart. How to tell if a houseplant is overwatered or underwatered lists the signs side by side.
If the soil is bone dry, water until it runs from the drainage holes. If the water runs straight through, the soil may have shrunk into a hard block. Bottom watering helps the soil soak up water again.
Not enough light
A plant in a dim spot makes less food. It cannot keep all of its leaves, so it lets go of the oldest ones first. The result is yellow lower leaves, slow growth, and long, stretched stems.
Move the plant closer to a window. Bright, indirect light suits most common houseplants. Light is weakest in winter, so a spot that worked in July may be too dim in December.
Natural aging
Every leaf has a life span. A plant that is otherwise healthy may turn one old, bottom leaf yellow every so often. Nothing is wrong. The plant is moving its energy to newer growth.
Look at the rest of the plant. If new leaves look firm and green and only the oldest leaf yellows, leave the care routine alone. Pull the old leaf off when it comes away easily.
Hunger
Plants use up the nutrients in potting soil over time. A plant that has sat in the same soil for a year or more may show pale green or yellow older leaves and weak new growth.
Feed with a houseplant fertilizer during the growing season, spring through summer. Follow the label for how much to use. More is not better, because extra fertilizer salts can burn roots. Skip feeding in winter, when most plants rest.
If you have not repotted in a long time, roots may fill the pot. Roots poking out of the drainage holes are a sign. A bigger pot with fresh mix gives the roots room and gives the plant new nutrients.
Too much direct sun
Strong sun can bleach leaves. They turn pale yellow or white, and then brown and dry in patches. The damage shows on the side of the plant that faces the window, and on the leaves that sit closest to the glass.
Move the plant back from the window or hang a sheer curtain between the plant and the sun. Sun-damaged areas will not turn green again.
Pests
Spider mites, aphids, and scale feed on leaf juices. Mites cause tiny yellow or pale dots, often with fine webbing near the stems. Scale looks like small brown bumps on stems and the undersides of leaves. Aphids cluster on soft new growth.
Look under the leaves with a bright light. Wipe the leaves and stems with a damp cloth and move the plant away from others. Check the plant every few days for new signs. Treat it until the pests are gone.
Cold drafts and sudden changes
Plants dislike a sudden move. A new home, a new window, or a blast of cold air from a door can lead to yellow leaves and leaf drop. Cold glass also harms leaves that touch it.
Keep the plant away from drafts, heater vents, and glass in freezing weather. Once the plant settles in a steady spot, new growth should come in healthy.
Yellow edges and brown tips
If the leaf edges turn yellow and then brown, the cause may be dry air, salts from tap water or fertilizer, or uneven watering. Why are my houseplant leaf tips turning brown goes through those causes one at a time.
What to do with yellow leaves
A leaf that has turned fully yellow will not turn green again. Cut it off at the base with clean scissors. Removing it helps the plant send energy to healthy growth. A leaf that is only partly yellow can stay if it still makes food, but many people remove it for looks.
Do not remove more than a small portion of the plant’s leaves at once. If many leaves are yellow, fix the cause first and trim in stages.
Change one thing at a time. If you move the plant, repot it, and change the watering all in one day, you will not know which change worked. Fix the most likely cause, then wait two to three weeks and watch the new growth. New leaves that come in green mean the fix worked.
Quick guide to the pattern
Lower leaves yellow, soil wet: overwatering.
Lower leaves yellow, soil dry, leaves crisp: underwatering.
Lower leaves yellow, plant leggy, dim spot: low light.
One old leaf yellow, plant otherwise healthy: natural aging.
Pale older leaves, slow growth, old soil: hunger or a crowded pot.
Bleached patches facing the window: too much sun.
Yellow dots and webbing: spider mites.
New leaves yellow with green veins: a nutrient problem or soil that is too wet or too alkaline. Check watering first, then feed.