The best way to sterilize plastic trays used for growing plants, especially in microgreen production or similar settings, involves several steps to eliminate pathogens like fungi and bacteria. Here are the most effective methods:
1. Bleach Solution
- Mix: Combine 1 part bleach with 9 parts water (10% bleach solution).
- Process: Soak the trays in the solution for about 10-15 minutes.
- Rinse: Thoroughly rinse the trays with clean water to remove any bleach residue.
- Dry: Allow the trays to air dry completely before reuse.
- Benefits: Bleach effectively kills most bacteria, fungi, and viruses.
2. Hydrogen Peroxide
- Mix: Use a 3-5% hydrogen peroxide solution.
- Process: Spray or soak the trays in the solution for about 10 minutes.
- Rinse and Dry: Rinse thoroughly and air dry afterward.
- Benefits: Hydrogen peroxide is less harsh than bleach, environmentally friendly, and effective against a wide range of pathogens.
3. Vinegar and Hydrogen Peroxide Combination
- Process: Spray trays with vinegar first, then follow with a spray of 3% hydrogen peroxide.
- Rinse and Dry: Rinse well and dry.
- Benefits: This combination can be highly effective for sanitizing surfaces.
4. Heat Sterilization
- Process: If your trays can withstand heat, you can sterilize them by placing them in an oven at 160°F (70°C) for about 30 minutes or using a commercial steam cleaner.
- Benefits: This method avoids chemicals and can be effective if done correctly.
5. Commercial Sterilizing Agents
- Products: Specialized disinfectants such as quaternary ammonium compounds (e.g., Physan 20) are often used in horticulture.
- Process: Follow the manufacturer's instructions for dilution and contact time, then rinse and dry.
- Benefits: These are designed for plant trays and offer broad-spectrum pathogen control.
Whichever method you choose, it's crucial to ensure the trays are completely dry before planting to avoid fungal growth.