Cleaning Seed Trays: Washing and Sanitizing Before Reuse
Cleaning seed trays lets you use flats and cells again next spring. Iowa State University Extension says old containers should be cleaned and disinfected each time you use them.
The short answer
Cleaning seed trays takes a brush, soapy water and a bleach soak. Iowa State says to remove loose soil, wash in soapy water, rinse and soak in one part household bleach to nine parts water for at least 10 minutes. Wisconsin suggests 30 minutes for reused pots, then a good rinse.
Why clean seed trays before reuse?
Old trays hold debris. Iowa State says fungi and other organisms can remain in old containers and their debris, then reach new plants. Minnesota Extension says most plastic seed starting containers are reusable. Reusing potting mix is covered in how to save money by reusing old soil.
How do you sanitize trays?
Wash, then soak. Iowa State says dish detergent works well. Mix the bleach solution by adding bleach to water and use it within two hours. Minnesota says a bleach or other disinfectant soak for 30 minutes works. Hydroponic gear is covered in caring for your hydroponic system.
| Step | Why | Source |
|---|---|---|
| Brush off soil | Clears loose debris | Iowa State |
| Wash in soapy water | Cleans the surface | Iowa State |
| Soak in 10 percent bleach | Disinfects | Wisconsin |
| Rinse well | Removes bleach residue | Wisconsin |
How should clean trays be stored?
Seal them. Wisconsin says to store pots or flats in sealed plastic bags so they are not contaminated. Tool care is covered in how to sharpen garden tools.
How to: step by step
- Knock out old mix and roots.
- Brush off any loose soil.
- Wash trays in soapy water and rinse.
- Soak in one part bleach to nine parts water.
- Rinse well to remove bleach residue.
- Store trays in sealed plastic bags until sowing.
Troubleshooting
Crust on the rim: Iowa State says a scouring pad removes mineral deposits from plastic.
Only one tray to clean: wipe it with 70 percent rubbing alcohol.
Problems persist in old plastic trays: Wisconsin says bleach may not always work on plastic. Replace those trays.
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Sources
- How to clean and disinfect plant containers, Iowa State University Extension
- Dampening damping off: tips on seed starting, University of Wisconsin Madison Extension
- Starting seeds indoors, University of Minnesota Extension
- Growing vegetables in containers, University of Wisconsin Madison Extension
FAQ
Can I use bleach on trays?
Yes. Iowa State says to soak cleaned containers in one part household bleach to nine parts water for at least 10 minutes, then rinse.
Do new trays need cleaning?
Wisconsin says to store new pots or flats in sealed plastic bags so they stay clean until use.
How often should trays be cleaned?
Iowa State says to clean and disinfect old pots each time you use them, whether plastic, clay or another material.
Can cell packs be reused?
Yes. Minnesota says most plastic seed starting containers are reusable once cleaned and soaked.
Can rubbing alcohol replace bleach?
Yes. Iowa State says you can wipe all surfaces inside and out with undiluted 70 percent isopropyl alcohol instead of a bleach soak.
