If you’re planning on reusing plastic seed trays year after year, then it’s essential that you clean and disinfect them first. Don’t worry, sterilizing seed trays isn’t difficult. Here are step-by-step instructions for how to clean them the right way.
Using dirty seed trays and cell is a very dangerous practice, and a very common mistake that new gardeners make.
Have you ever had an entire flat of seedlings shrivel up and die on you? This is one of the biggest frustrations I hear people talk about when they are new to growing seeds.
There is nothing more frustrating than spending all that time starting your seeds, then getting super excited when they finally germinate, and babying them for weeks… only to watch the entire tray of seedlings shrivel up and die off at the base. Ugh, it’s not pretty!
The answer to why your seedlings shrivel up and fall over at the base is actually very simple.
Your seedlings keep dying because they suffered from a common seedling problem called damping off (also known as seedling blight).
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Seedling damping off is caused by seedling blight, a soil borne disease that attacks and kills seedlings. Damping off is caused by reusing dirty growing flats and trays that have been infected with seedling blight.
Seedling blight lives in the soil, and can survive in dirty plant flats and trays year after year. The good news is that damping off is easily preventable.
To prevent damping off when starting seeds indoors, it’s essential that you disinfect all of your plastic grow trays, seed cells, and seedling tray covers before you reuse them.
It’s fine to use brand new seed cell flats and trays right out of the box, but used indoor seed starting equipment should be always be disinfected every time you reuse it.
Cleaning and sterilizing seed trays is the easiest way to prevent seedling blight, and it will save you tons of time (and heartache) in the long run. Washing and disinfecting seed trays between uses also helps to prevent mold on seedlings.
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Supplies Needed:
Instructions:
Step 1: Wipe the loose dirt out of the plant tray inserts and cell trays using a paper towel or small cleaning brush.
Step 2: If there’s any dirt that is hardened on, you can soak the seed planting trays and wash them in warm soapy water. You don’t have to be super fussy about cleaning seed trays in this step, but it’s a good idea to remove as much of the dirt as you can.
Step 3: After cleaning seed starting trays, disinfect them by soaking them in a bleach and water solution. I recommend using a solution of 1 part bleach to 9 parts water to disinfect your seed flats, and soaking them for 15-20 min.
You can use a five gallon bucket to disinfect seed cells and trays, but keep in mind that you’ll have to flip the plant trays over in order to disinfect both ends.
My preferred method is using a large plastic bin (which just happens to be the same bin I use to store my seedling trays) so I can sterilize several growing flats and cell trays at the same time to speed things up.
Step 4: Once they’re done soaking, give them a quick rinse and let them air dry. Now they are sterilized and ready to use for starting seeds.
Ok, ok – I know what you’re thinking. Yes, disinfecting seeds trays and cells will take you a little extra time, but the effort is well worth it to ensure your seedlings have a healthy start.
Trust me, skipping this step in order to save yourself a little extra time is not worth the risk of your seedlings dying.
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If you don’t have any seedling trays yet, you can find them for sale anywhere you can buy seeds.
Keep in mind that many big box stores and garden centers won’t carry seed starting supplies until late winter or early spring, so sometimes you have to be patient.
Of course, you can always find seed starting kits for sale online at any time during the year. If you don’t need the whole kit, you can find cell inserts, humidity dome lids and seedling trays for sale separately.
Dealing with damping off is definitely one of the biggest struggles many gardeners face when starting seeds indoors, and it is no fun!
If you want to learn exactly how to grow your own seeds step-by-step, then you should take my online Seed Starting Course! This fun, self-paced, comprehensive online course includes guidance and support, and provides everything you need to learn in order to grow any type of plant you want from seed. Enroll in the course today!
Or, if you just need a refresher to grow seeds indoors, then my Starting Seeds Indoors eBook is for you! It’s a quick-start guide that will give you the guidance you need to get your indoor seedlings off to a heathy start!
Share your tips for disinfecting seed trays in the comments section below.
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