Guides
Why are my plant leaves turning yellow?
Yellow leaves can come from watering, light, feeding, pests, cold or disease. Start with the compost, then work through the common causes below. Watering problems come first because they affect many houseplants in any climate.
Check the compost first
Watering causes more yellow leaves than anything else on this page. Push a finger into the compost to the second knuckle. Wet, heavy or sour-smelling compost points to overwatering. Dry, light compost that has shrunk from the side of the pot points to underwatering.
Work down the list
Too much water
- What you would see
- The oldest leaves at the base yellow first and drop, the plant may wilt even though it has just been watered, and the compost has stayed wet for a fortnight.
- The check
- Lift the plant out of its pot. Healthy roots are white or tan and firm. Rotted roots are brown to black and soft, and the outer layer slides off when you pinch them.
Too little water
- What you would see
- Leaf edges and tips go brown and crisp before the yellowing spreads, the lower leaves are shed first, and the whole plant looks limp on a warm afternoon.
- The check
- Lift the pot. A dry one is noticeably light, and the compost has pulled away from the sides so that water runs straight down the gap and out of the bottom.
Normal old leaves
- What you would see
- One leaf at a time at the very bottom of the plant, yellowing evenly and then dropping, while everything above it is green and growing.
- The check
- Count how many. A monstera or a rubber plant can shed its lowest leaf every couple of months as part of normal growth. Three or four yellow leaves at once point to another cause.
Not enough light
- What you would see
- The whole plant is pale rather than one leaf turning yellow. New leaves are smaller than the old ones, stems have long bare stretches, and the plant leans towards the window.
- The check
- Stand where the plant stands and look at the window. If you cannot see a good piece of open sky from that position, the plant is probably not getting enough light.
A nutrient shortage
- What you would see
- Yellowing follows a pattern. The leaf may yellow between green veins, or the whole plant may look pale and small.
- The check
- Note whether it started at the bottom of the plant or the top. Bottom means a mobile nutrient such as nitrogen or magnesium; top means an immobile one such as iron, which is usually a pH problem rather than a shortage.
Sap-sucking pests
- What you would see
- Yellowing with the leaf surface also dulled, stippled or sticky, and often worse on one part of the plant than another.
- The check
- Turn a leaf over and look at the underside with the light behind it. Fine pale speckling and webbing at the shoot tips is red spider mite; brown domes on the veins are scale; white fluff in the joints is mealybug.
Cold, draughts or a recent move
- What you would see
- Yellowing that appeared within a week or two of the plant being moved, repotted or left near an open door in winter.
- The check
- Think back over the last three weeks. Tropical houseplants can drop leaves after a change in position, a cold delivery van or a night beside a draughty window. The leaf drop should stop once the plant settles.
A leaf disease
- What you would see
- Yellowing forms around defined marks rather than spreading evenly, and it gets worse week by week.
- The check
- Turn the leaf over again. Raised pustules that rub off as coloured powder are rust. Flat dark blotches with a fringed edge on a rose are black spot.
Root pests
- What you would see
- A container plant that yellows and then collapses over a few days, usually in autumn or spring, with no obvious cause above ground.
- The check
- Tip the pot out. White C-shaped grubs with orange-brown heads are vine weevil, and there will be very little root left.
Still not sure which one it is? Photograph the leaf and compare it against the full library.