Growing a Bacteria Garden | Totally Gross Science for Kids

My kids love all things squishy, slimey,  and gross… Creepy crawlies, petri-dish snacks, and pretty much anything that makes you say “ewwww”.

The other day I walked into my kitchen to see the kids a little too close to the trash can for my comfort level, so I asked what they were up to.

“We’re observing!” my four year old said brightly.

Oh no… What in the world could they “observe” from a trash can?

“I want to see if something will grow!”

I’m okay with a lot of gross science experiments, but digging around the trash can? Not my favorite thing.

I knew I needed to find an activity that would feed that curiosity and love of “grossness”, and thankfully I came up with this super fun bacteria gardens gross science for kids!

Growing Bacteria Gardens | Gross Science for Kids

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Bacteria Garden Gross Science for Kids

If you’re looking for gross science experiments, you cannot get much grosser than this one!

Kids will love watching how bacteria and mold can grow right before their eyes, even if they don’t have a microscope to see it.

Please note: Since this activity is all about cultivating bacteria and mold, children should NOT open the containers after their gardens are completed. Children should wash their hands after handling the agar plates.

Growing Bacteria Gardens | Gross Science for Kids

How to Grow a Bacteria Garden

There are two ways to start your agar plates. You can either purchase pre-made agar plates for a truer, cleaner experiment or make your own agar plates like we did.

Just know, if you do make your own agar plates this way, your “bacteria” garden will be more of a mold garden due to contamination.

Growing Bacteria Gardens | Gross Science for Kids

You will need:

Growing Bacteria Gardens | Gross Science for Kids

Boil the chicken broth in a pot. Add a few drops of food coloring and sprinkle in some Xanthan gum. Mix until all clumps are gone and the mixture is thick.

Allow to completely cool.

Label a container with each child’s name.

Have the kids swab their tongues (told you this was gross science!) with the cotton swab and rub it onto the surface of the agar plates in whatever design they want.

Close the lid and place on top of the refrigerator.

Wait 1-2 weeks.

Growing Bacteria Gardens | Gross Science for Kids

Pull down the “bacteria gardens” and see what’s growing!




In our bacteria gardens, we had two drastically different results. In garden one, mold had taken over. But in garden two, bacteria was growing strong!

The kids noted that the bacteria had much more interesting shapes than the mold.

Growing Bacteria Gardens | Gross Science for Kids

Looking for more STEAM (Science, Technology, Engineering, Arts and Math) projects and inspiration?

Looking for some more STEAM inspiration that use can use right now for the holidays? Instant gratification style? Check out the STEAM Kids Halloween Bundle! You can grab the STEAM Kids Book with 50+ Hands-on STEAM Activities AND STEAM Kids Halloween with fun and spooky STEAM activities to do all October long! It’s packed full of a year’s worth fun learning activities that will wow the boredom right out of your kids!

For More Adventures in STEM Learning, Check Out:

50 totally awesome STEAM Projects for Kids


Discover how to get siblings to get along even when all they do is annoy each other with the Sibling “Get Along” Poster Pack!

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