Why does my Calathea have yellow leaves?

Start by reading the pattern

Calatheas are fussier than most houseplants, so the same yellow leaf can mean different things depending on which leaves are affected and how they feel. Before you change anything, look closely.

One old leaf at the very bottom turning evenly yellow, while everything above it stays firm and green, is almost always natural aging. The plant sheds its oldest growth as it puts energy into new leaves, and there is nothing to fix. But if several leaves yellow at once, or the yellowing creeps up from the base with soft, mushy stems and soil that stays wet, you are looking at overwatering and likely the start of root rot. That distinction tells you whether to relax or to act.

Why soggy soil is the usual culprit

Calatheas want soil that stays evenly moist but never waterlogged, and that narrow window is easy to overshoot. When the soil sits saturated, the roots cannot get oxygen, they begin to rot, and they stop delivering water and nutrients upward. The leaves respond by yellowing, starting low and spreading. A pot with no drainage hole, or one left standing in a full saucer, makes this far more likely. For more on how excess water damages roots, see the Missouri Botanical Garden's overwatering guide.

To confirm root rot, slip the plant out of its pot. Healthy roots are firm and pale; rotting roots are brown, soft, and may smell sour. If you find them, trim the mush away with clean scissors and repot into fresh, airy mix.

The other causes, ranked

• Underwatering. If the soil is bone dry and pulling away from the pot wall, the plant cannot take up water. Yellowing here usually comes with crispy, curling edges rather than soft, mushy leaves.
• Hard or fluoridated tap water. Calatheas are sensitive to the salts and minerals in tap water. This shows more often as browning, crispy edges than as full yellowing, but a struggling, salt-stressed plant can yellow too. Use filtered, distilled, or rainwater, or leave tap water out overnight before using it.
• Too much direct sun. Harsh midday rays bleach the foliage. Look for pale, washed-out patches on the side facing the window. Calatheas want bright indirect light, not direct sun.
• Old, spent soil. Soil that has not been refreshed in a year or two runs low on nutrients, and the whole plant can pale to an even, dull yellow across many leaves at once.

A quick self-check

If only the newest leaves are affected while the older leaves stay green and firm, that points to underwatering, water quality, or low humidity, not overwatering. Overwatering and aging both start at the bottom. New-growth problems start at the top.

How to fix yellowing leaves

1. Check the soil moisture. Feel the top inch. If it is wet, wait. If it is dry and crumbly all the way down, you have been underwatering.
2. Fix drainage. Use a pot with a drainage hole and empty the saucer so roots never sit in standing water.
3. Water for even moisture. Water thoroughly until it drains, then let only the top inch dry before watering again. Aim for evenly moist, never soggy and never bone dry.
4. Switch your water. Use filtered, distilled, or rainwater, or leave tap water out overnight, to avoid mineral and fluoride buildup.
5. Raise the humidity. Calatheas prefer 50 percent humidity or higher. Group plants together, use a pebble tray, or run a humidifier in dry rooms.
6. Adjust the light. Move the plant into bright indirect light, out of any direct sun.
7. Remove spent leaves. Cut fully yellow leaves at the base with clean scissors so the plant stops feeding a leaf that will not recover.
8. Refresh feeding and soil. During spring and summer growth, feed at quarter to half strength every few weeks, and repot in fresh mix every year or two.

Calatheas are also happiest in stable warmth, roughly 65 to 80 F (18 to 27 C), and away from cold drafts and heating vents that dry them out. Popular cultivars like orbifolia, medallion, lancifolia (rattlesnake), and white fusion all share these same preferences, so the care above applies whichever one you grow.