Fertilizer or mineral salt build-up

Bigger crispy patches plus tap water usually means salts have built up in the soil and are burning the roots.

Diagnosis

Fertilizer or mineral salt build-up

What's happening

Excess fertilizer salts and the minerals in hard tap water accumulate in the potting mix over time. They draw moisture away from the fine roots and burn the root tips, and that damage shows up as larger brown, crispy patches across the leaf rather than a tidy rim, often with a whitish crust on the soil surface or pot rim.

How to fix it

Flush the soil thoroughly: run plenty of filtered or distilled water through the pot until it drains freely, repeating several times to leach out the salts. Then cut back on feeding to a balanced liquid fertilizer at quarter to half strength, only every 4 weeks during spring and summer — Calathea is a light feeder. Switch to filtered or distilled water going forward so the build-up doesn't return.

What fixes it

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

Reviewed June 2026 · how we check this