White mold on potting soil is often a harmless saprophyte for people, but it is a clear signal: the surface stays wet too long and air is stagnant. Ignore it and roots are next.
Mold vs Salt Crust vs Gnats
Fertilizer crust is hard and crystalline; mold is cottony. Fungus gnats are flying insects, not fungi. Both love wet mix, but treatment differs. Flying pests: pests. Salt crust: fertilizing.
Why It Appears
Overwatering, a full saucer, no drainage holes, heavy garden soil, constant misting, and packed pots with no airflow. Do not confuse leaf humidity with wet soil; raise air humidity via the humidity guide, not by keeping the surface soaked.
What To Do
- Scrape off the top centimeter (do not home-compost a heavy bloom).
- Water less and empty saucers: watering.
- If roots are black and smelly, replace the mix: soil and repotting.
- Cinnamon is a weak helper. Dry surface and airflow do the real work.
Prevent With the Right Pot
Terracotta helps the surface dry in a humid room: pots. If Jaliz keeps logging wet soil, stretch the reminder interval.
Is the Mold a Health Risk?
Brief contact is mild for most people, but sensitive folks should not stir a heavy bloom without a mask. Do not harvest edible herbs from a moldy surface until you replace the top layer. A strong rotten smell is root rot, not just surface mold.
How Long Until It Stops Returning?
Keep the surface drier for one to two weeks and water only when the mid-layer is dry. If mold returns, check a blocked hole or nighttime misting that holds moisture until morning.