What is white crust?

In porous material water pushes through and then evaporates, leaving the minerals to dry up on the surface. Usually this doesn't cause any issues to your plants health, but some plants are more sensitive to mineral build up than others.

Signs

Common causes

Mineral residues comes from the water you use or minerals from the fertilizer, soil, or clay in the pot. Plants that are sensitive to salt, like ferns and some tropical plants, may be more prone to accumulation.

Overfertilizing

What to think about

Flush your plant once in a while with neutral water. Flushing every few months or when you notice salt deposits is recommended. Use rain water, reversed osmosis water or distilled water to flush through the soil and pot.