Sometimes I have a hard time being flexible.
I’ve been like that for as long as I can remember… If we had something on the calendar growing up, it was gonna happen. No ifs, ands, or buts about it. And if it didn’t? Well, I pretty much had a meltdown.
I’ve grown out of the meltdown part (although my husband might try to argue that point…), but dang it– if I put something on the calendar, you can bet I’ll go to the ends of the earth to make sure it happens.
Let’s just say it’s a blessing and a curse.
This does tie into today’s post, I promise.
So I had “plant tomato and pepper seeds” written on my calendar for the ‘project of the day’ last Saturday. I cleaned up the kitchen after breakfast, got the kids occupied with a project, and headed to the basement to dig out my big box o’ seed stuff.
That’s when I discovered I had a grand total of 8 little coconut coir pellets left. And approximately 2 cups of potting soil. This was a problem.
Way to go, Jill. Way to go.
A quick visit to Amazon got 200 of the little pellets (affiliate link) on their way to my house via USPS, but that wasn’t going to help me that day.
But I wasn’t about to abandon my seed operation. I was determined, y’all. It’s February. I haven’t touched a plant in months. I HAD to do something so I could pretend I was gardening. So I decided to give my seed trays and flats a good scrub and disinfecting, which is how this blog post was born. Poor planning for the win, I suppose.
Do You Really NEED to Disinfect Seed Trays?
Maybe. Probably not? I don’t know.
How’s that for an answer?
Truth be told, I don’t always disinfect my seedling flats, pots, cups, or trays. If you’ve been following me for any length of time, you know I’m NOT a germaphobe, and I’m pretty laid back about such things. (I rarely even sterilize my chicken coop for new chicks— I believe in the power of good bacteria.)
However, if you’ve had issues with any sort of plant disease, fungi issues, or damping off (more on that below), I would definitely plan on cleaning and disinfecting your seed starting equipment before you start your seeds each year.
It’s cheap insurance to prevent big issues like damping off, which can be borderline devastating when you’re anxious to get your seeds rolling. (And Lord knows we are…)
What is Damping Off?
You plant the seed.
You water the seed.
The seed begins to emerge from the soil and you get all excited.
And then said seedling shrivels and DIES with no explanation.
That’s damping off. It’s so rude.
For the more technical-minded, damping off is a disease of seedlings caused most commonly by fungus or mold. Sometimes it affects just a handful of your seeds, while other times it can wipe out entire trays of fledgling plants.
Needless to say, you don’t want to be dealing with damping off, so it’s wise to take simple precautions to prevent it.
How to Prevent Damping Off in Seedlings:
- Don’t reuse dirty potting soil
- Keep your seedlings warm while they are sprouting (our basement is cold, so I keep a small heater in the room and run it on low heat)
- Water seeds or seedlings with lukewarm water, not ice cold
- Don’t crowd seedlings
- Provide seedlings with sufficient light (usually 12-16 hours of consistent light– oftentimes window light is not enough. I use fluorescent lights for my seed starting set up.)
- Clean and disinfect pots, flats, and trays before you use them to start seeds, which is what we’re talking about today.
How to Disinfect Seed Trays
Not surprisingly, the most common way people disinfect or sterilize seed starting equipment is with bleach. The Internet has such a fascination with bleach, but I can’t stand the stuff.
Thankfully, hydrogen peroxide comes to the rescue. Yup, just plain old, drugstore-strength, 3% hydrogen peroxide. Easily available, cheap, and much less stinky. Bingo.
Here’s how I disinfect my seed trays the natural way– no nasty bleach required:
Shake out any residual soil from the seed trays and flats. You may need to soak everything in a bit of water if any soil is dried on and super crusty.
Scrub the trays and containers with warm, soapy water. I used a bit of my #1 favorite natural cleaning concentrate in the entire universe for this part, On Guard Cleaning Concentrate. This concentrate, by itself, will likely eliminate most of the issues that cause damping off, so I figure using it alongside hydrogen peroxide is the perfect one-two punch. If you don’t have any On Guard cleaner, you can use regular soap and water. (And then order some On Guard Cleaner. You’ll thank me later.)
Spray the trays, flats, cups, or whatever with a generous spritz of hydrogen peroxide, then let everything sit for 20 minutes.
Wipe with a clean, dry cloth, and you’re ready to plant! Pretty easy, eh? Disinfecting your seed equipment is a project you can easily complete in a morning or afternoon and it’s a simple way to eliminate one of the biggest causes of damping off.
Seed Tray Disinfecting Notes:
- I would recommend doing this project outside. It was stupidly cold and windy the day I did it, so I opted to wash in my laundry room tub. However, it’s a messy task that’d be better suited for a warm spring day where you can use a big plastic tub outside, or something along those lines–especially if you have a lot of trays. Also, leaving your seed trays to dry in the sun for a while is another way to kill off any bad stuff that may be lingering inside.
- What about vinegar? Yeah, I know– I was wondering the same thing. Using vinegar was my initial thought, but I’m not certain it has enough punch to kill off all the problematic microorganisms. And if I’m going to go to the trouble of disinfecting everything, I want to be sure the effort was worth my time, which is why I opted for hydrogen peroxide instead. If you do want to try vinegar, you could spray the rinsed flats and pots with a spritz of white vinegar, wipe, and then follow with another spritz of hydrogen peroxide.
- If you want to know all the details of our laundry room washtub sink, here’s a post with all the details.
Other Seed Starting Posts You’ll Love:
- Our DIY Seed Starting Set Up
- The Ultimate Seed Starting Guide
- How to Make Paper Pots
- DIY Soil Block Maker
- Where to Buy Heirloom Seeds
- How to Test Seeds for Viability
Jessie @ This Country Home says
Great article! Thank you for the hydrogen peroxide tip, I’ll have to make sure and do that this year-I hate bleach too!
Ingrid McCord says
How is it that you think bleach is a nasty chemical but hydrogen peroxide is not??
Jill Winger says
hydrogen peroxide is far less likely to cause respiratory issues, skin irritation, and headaches. https://draxe.com/dangers-of-bleach/
It’s probably the smell bleach gives off whereas Hydrogen peroxide doesn’t. However, hydrogen peroxide is naturally occurring in nature and breaks down rapidly into water and oxygen. Bleach, on the other hand, is a chemical mixture derived from natural sources used for oxidizing.
How do you use coconut coir pellets?
Jill Winger says
I use them to start my seeds: https://www.theprairiehomestead.com/2016/03/seed-starting-system.html
What is the ratio of Peroxide and water for disinfecting?
Jill Winger says
I don’t really have a ratio– I just spray the peroxide on straight to the rinsed trays
I stopped using plastic to start my plants. I go to the dollar store and get the kids flat bottom ice cream cone cups. I use several cake pans to set them in. fill them with dirt and start my plants. then when I plant them it goes into the ground to break down into the environment. much faster than the purchased bio degradable type and faster than the formed paper. take care for they do fall apart easily when wet I set them close together and the sides of the cake pan keeps them standing and makes it easy to move.
Jill Winger says
Shelley S. says
FYI – a sprinkle of ground cinnamon on the soil after planting your seeds will prevent the fungus which causes damping off.
Jill Winger says
Oooh, great tip!
Amanda Carew says
I’m a newbie gardener so posts like this are really beneficial to me since I know basically nothing. lol. Now I know how to disinfect my seed trays! So thank you! 🙂
I couldn’t agree more! No gardener feels happy to see newly germinating seedlings suddenly drying up. I think most people under-estimate the importance of disinfecting the seedling trays but your post is an eye-opener for many gardeners.
Donna Kelso says
I like that spray bottle top on the hydrogen peroxide! I never use bleach in or around my home. I use Dr. Bronner’s 18-1 Hemp Eucalyptus Pure Castile Soap for EVERYTHING. It now comes in many scents like Lavender, etc. I’ve been using it since the 60’s, it is pure, made with organic oils – just purrfect for everything, head to toe and all around the house.
You can also use colloidal silver for the final spray. If you have a generator, it’s cheap and very effective.
Great post, Jill. Thanks for sharing your easy-to-follow steps of disinfecting seed trays equipment. I just wonder whether using baking powder mixed with vinegar and lemon would also work as a good disinfectant?
Mary Smith says
What a great post! I’m inspired to do something similar for my site (that is, if you don’t mind me running off with your idea!) because so many people are dipping their toes into Veg gardening especially how to disinfect supplies and I wrote an article on Best Plant starter growing trays on my website https://bestgardeninggiftsideas.com/ and we want them all to be successful and fall in love with it as we have!
Michelle GG says
I couldn’t wait to get my hands in the dirt also, so I started growing microgreens and baby lettuce indoors. That’s when I learned about using Hydrogen Peroxide. But store bought 3% has a chemical stabilizer in it, so I got myself some 6% Food Grade H2O2 off Amazon, while ordering flats and other gardening supplies. I dilute it to 3% or 1%, depending on what my needs are. Great timely article. I’ll have to look up your zone as I wasn’t even thinking it was time yet to plant tomato or pepper seeds in my zone 5A. This is the first year I’m doing that instead of buying nursery plants.