Too much sun or a feeding gap

What's happening

New blades bleaching to a pale, washed-out yellow on the window side point to too much direct sun scorching tender growth — Cast Iron Plant is a deep-shade plant and burns easily. Pale, weak new shoots with no recent feeding instead point to a nutrient shortfall, since fresh growth is the first to show a lack of food.

How to fix it

Move the plant out of any direct sun into the low-to-medium indirect light it prefers. If feeding is overdue, start a balanced liquid fertilizer at half strength once a month through the growing season. New shoots that unfurl after the change should come in a healthy deep green.

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