How to tell
Overwatering & root rot. The soil is still wet days after watering, the lower and oldest leaves yellow first, and the crown may feel soft. This plant’s dense, fine roots rot faster than a tougher foliage plant’s, and yellowing leaves is usually the very first sign.
Tap-water minerals (a real trigger on this plant). Unlike most houseplants, Pinstripe calathea is genuinely sensitive to the salts and fluoride in ordinary tap water: a general, all-over yellowing with no soggy soil and no light problem often traces back to this rather than watering technique.
Too little light. The yellowing comes with dull, fading leaf patterning and pale new growth leaning toward the nearest window. Pinstripe calathea wants medium, indirect light. Together, those changes show that the spot is too dim.
Thirst (underwatering). The soil is bone dry, and the yellowing arrives alongside crispy brown edges rather than soft, mushy growth.
Hungry (nutrient shortfall, but easy to overcorrect). Older leaves fade evenly and growth has slowed after many months unfed, but this genus is also easily salt-burned by fertilizer, so don’t overcompensate.
Simple old age. One of the older, largest leaves slowly yellows from the outside in over a couple of weeks, while the new furled leaves emerging from the centre look completely healthy. This is normal retirement on a Pinstripe calathea, not a symptom.
