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How to Sanitize Seed Starting Supplies


For the best chance of success when starting seeds indoors or in a greenhouse, it’s crucial to begin with clean and sanitized supplies. Young seedlings are vulnerable to fungal and bacterial diseases. Clean trays and containers mean less chance of seedlings dying or “damping off”. Learn how to sanitize seed-starting supplies with these simple steps.

Clean trays and containers mean less chance of seedlings dying or “damping off”. Learn how to sanitize seed-starting supplies with these simple steps.

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Follow these simple steps for cleaning and sanitizing your seed-starting supplies: 


1. Gather needed supplies

You may already have everything you need to sanitize your seed starting supplies. It’s easiest to work outside.

You’ll need an area (size depends on the number of seed-starting supplies) to spread out and spray off the supplies. 

You’ll need an area (size depends on the number of seed starting supplies) to spread out and spray off the supplies.

A large tub (or two) for washing, rinsing, and submerging seed trays and containers.

A large tub (or two) for washing, rinsing and submerging seed trays and containers
You may already have everything you need to sanitize your seed starting supplies. It’s easiest to work outside.

2. Remove debris and wash seed trays and supplies

Seed trays, domes, and containers are dirty and need some elbow grease to get cleaned up and ready for the next season.

Remove debris and wash seed trays and supplies
Fill the large tub with water and add a mild detergent. 

Fill the large tub with water and add a mild detergent. 

Submerge the containers and use the sponge or brush to scrub and dislodge all the dirt and debris. (Rinsing alone usually isn't enough to get the dirt and soil off.)

Submerge the containers and use the sponge or brush to scrub and dislodge all the dirt and debris. (Rinsing alone usually isn’t enough to remove the dirt and soil.)

Lay out trays and containers, and rinse off with a spray of water. 

Lay out trays and containers, and rinse off with a spray of water

Repeat with remaining seed trays and supplies. 

Repeat with remaining seed trays and supplies

How to Sanitize Seed Starting Supplies


3. Spray trays off with a diluted vinegar solution

Once the trays are clean, spraying them with a vinegar solution can help remove water spots.

Once the trays are clean, spraying them with a vinegar solution can help remove water spots.

Mix equal parts vinegar and water in a spray bottle. 

Once the trays are clean, spraying them with a vinegar solution can help remove water spots.

Spray off all surfaces with the vinegar solution.

Once the trays are clean, spraying them with a vinegar solution can help remove water spots.

Allow the solution to stay on for ten minutes, then rinse.


4. Use hydrogen peroxide to finish sanitizing your seed starting supplies

There are two methods for completing this step; choose the one that best suits your situation.

Use hydrogen peroxide to finish sanitizing your seed starting supplies

To quickly sanitize seed starting supplies:

  • Put hydrogen peroxide (3%) in a spray bottle.
  • Spray all surfaces of the trays and containers with hydrogen peroxide.
  • Let it sit for 10 minutes, then rinse thoroughly.
  • Air dry.

If damping off and fungal diseases have been an issue in the past, you may want to use this method, which provides the highest level of sanitation: 

If damping off and fungal diseases have been an issue in the past, you may want to use this method, which provides the highest level of sanitation: 
If damping off and fungal diseases have been an issue in the past, you may want to use this method, which provides the highest level of sanitation: 

Note: 12% hydrogen peroxide can cause skin irritation. Wear chemical-resistant rubber gloves when using. 

how to sanitize seed starting supplies


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If this post about how to sanitize seed-starting supplies was helpful, please share it:


Ryan

Monday 15th of April 2024

I’m curious why you use both vinegar and hydrogen peroxide? Would one or the other be sufficient?

Angela Judd

Tuesday 16th of April 2024

That's what the supplier (Bootstrap Farmer) of the seedling trays I use recommends - so I follow their recommendations for cleaning them when possible.

Cindy

Wednesday 20th of December 2023

Could I sanitize with a 10% bleach & water solution instead?

Angela Judd

Tuesday 26th of December 2023

That works too. Rinse well after use.

TJ

Thursday 13th of April 2023

Do I need to sanitize new trays from the source you recommend?

Angela Judd

Tuesday 18th of April 2023

A quick spray of water is probably good before the first use.

Gene

Thursday 15th of September 2022

appreciate the post on sanitizing seed starting gear:) Do you have a post on how you built the work table featured in this post? What is that plastic grid table top? I'd like to build one for myself! Thank you:)

Angela Judd

Thursday 15th of September 2022

I purchased it several years ago from a greenhouse supply store online, I don't remember which one.