Tap Water Brown Tips on calathea
What's Happening
Hard tap water contains dissolved calcium carbonate, magnesium, and other mineral salts ranging from 100-300+ ppm depending on region. As Calathea transpires, water evaporates from leaf margins while minerals accumulate. Over 4-8 weeks, salt concentration at leaf edges reaches toxic levels, causing osmotic stress that dehydrates leaf cells from the outside in. This creates the characteristic brown, crispy tips that cannot be reversed once formed.
How to Fix It
- 1
Test water hardness with inexpensive test strips (target <50 ppm for sensitive plants)
- 2
Switch to distilled or rainwater as primary water source
- 3
If using tap water: flush soil monthly with 2x pot volume of distilled water to leach salts
- 4
Add pebble tray with distilled water (not tap) to increase humidity without adding minerals
- 5
Consider repotting in fresh soil if white mineral crust visible on soil surface
How to Prevent It
Maintain water total dissolved solids (TDS) below 100 ppm for Calathea. Use water softening systems that specifically target mineral ions.