What to Do If Fungus Appears on Your Microgreens — Step-by-Step Fix

✍️ Sonia Pardasani, Co-founder BageechaBox | 🕐 6 min read | 🛡️ Troubleshooting Guide

You open your tray and see white fuzzy patches spreading across the surface. Don't panic — fungus is one of the most common problems in microgreens growing, and if caught early, you can often save the tray. Here's exactly what to do.

First — Is It Root Hairs or Fungus?

Before doing anything, do the spray test: mist the fuzzy area with water.

• Root hairs: Fine, uniform white threads radiating from the base of the stem. They collapse flat against the root when sprayed. No smell. Completely normal and healthy. ✅
• Fungus: Cottony or fluffy patches that stay fluffy or look slimy after spraying. Often has a musty or sour smell. Spreads visibly over 24–48 hours. ❌

If it stays fuzzy after the spray, it's fungus. Act immediately.

Why Does Fungus Appear?

1. Overwatering — wet cocopeat surface is the #1 cause.
2. Poor airflow — stagnant air allows spore concentration to build.
3. High seed density — too many seeds prevents air from reaching the medium surface.
4. Dirty trays — reusing trays without sterilisation carries spores from previous batches.

5-Step Rescue Plan

Step 1 — Stop Top Watering

Switch to bottom watering only. This keeps the canopy and surface dry.

Step 2 — Increase Airflow

Position a fan to circulate air gently around the tray. In humid cities, keep it running 24 hours.

Step 3 — Apply Cinnamon Powder

Sprinkle a light dusting of cinnamon (dalchini) directly over the affected area. Natural antifungal. Don't overdo it.

Step 4 — Hydrogen Peroxide Spray (Moderate Cases)

Mix 1 tablespoon 3% hydrogen peroxide in 1 cup water. Spray lightly on affected area. Safe for plants, lethal for fungal spores.

Step 5 — Know When to Discard

If fungus covers more than 30% of the surface, smells strongly, or spreads to stems — discard the tray. Start fresh with clean trays and sterilised cocopeat.