Underwatering

What's happening

Prayer plants are thin-leaved and thirsty, with shallow roots that resent ever drying out completely. When the soil goes bone dry the plant can't keep its oldest leaves hydrated, so they yellow and curl while the soil shrinks and pulls away from the side of the pot.

How to fix it

Water thoroughly until it drains from the bottom. If the water runs straight through dried-out soil without soaking in, bottom-water instead: set the pot in a few inches of water for 20–30 minutes, then drain fully. Maranta does best on a consistent rhythm, so check the soil every few days and water once the top inch starts to dry rather than waiting for it to crisp.

This is general guidance based on common symptoms; individual plants vary.