Petri Dish Treats are the perfect edible spooky science snacks for a fun and eerie Halloween party! These gelatin bites are quick, easy, and fun to make.
You could make these ahead of time for the party, or let guests and kids make their own. It’s a great kid-friendly Halloween project that doesn’t take any skill, even the littles will enjoy making their own science experiments!
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How to make creepy petri dish gelatin
First, you’ll want to grab all of your materials and get them set up.
Make sure you have the petri dishes. I ordered mine on Amazon. Grab yours with my affiliate link.
Each person decorating may want a rimmed baking dish or their own to help contain any spills or sprinkle explosions. Line the baking dish with parchment paper for added protection.
You can use so many things for the decorations! Go to the candy aisle at the store for inspiration.
Some starter ideas for the “bacteria” and add-ins: sprinkles, gummy worms, candy eyeballs, Nerds, Chewy Sweet Tarts, flower sprinkles (can look like organisms), food coloring, etc.
Make the gelatin
Next, start the gelatin.
Combine gelatin and water in a microwave safe bowl or measuring cup. I like the measuring cup because it has a pour spout which comes in handy later.
Microwave that in 15 second intervals until it’s melted. Now add the juice.
If you don’t have a microwave, you can heat the gelatin on the stove, it’ll just take longer.
Choose any flavor and color of juice that you like. I wanted mine to be lightly colored and slightly yellow so it looks like the agar medium that’s used in science.
I used pineapple-orange-guava juice. Apple juice, white grape juice, or even lemonade will work. Remember, your treats will taste like this juice when they are all done, so be sure you like the flavor.
You can even make an adult version and fill them up with some booze. Just replace some of the juice with vodka for adult petri dish jello shots.
Divide the gelatin mixture between 14 petri dishes. The number of dishes may vary if yours are bigger or smaller than mine.
Fill them 3/4 of the way up, some of the decorations are going to take up space, adding to the volume in the petri dish.
Now the fun part! Decorate them.
Before the jelly has set, place candies, sprinkles, and food coloring in the petri dish. The drops of food coloring can look like mold. You can swirl the food coloring in a bit with a toothpick. The edges of the food coloring will probably feather a bit as the gelatin sets.
Transfer the dishes (this is another good reason to use the baking trays) to the fridge to chill and set for about an hour.
Your budget-friendly gelatin petri dishes are ready! Serve ‘em at your next mad-scientist or Halloween party! They also work for a science themed birthday party as a fun dessert.
My Halloween Brain is another great party idea!
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Petri Dish Recipe
Petri Dish Treats
- microwave safe glass measuring cup
- Petri dishes
- 3 tablespoons powdered unflavored gelatin
- ¼ cup water
- 2 cups fruit juice
- candy and sprinkles
- food coloring
- Combine the gelatin and water in a microwave safe glass measuring cup. Microwave in 15-second intervals until the gelatin has melted, stirring after each time.
- Mix the fruit juice into the gelatin, and whisk until well combined.
- Place the petri dishes on baking sheets to help move them and contain messes.
- Divide the gelatin juice evenly between 14 new clean petri dishes, filling about ¾ of the way full.
- Before the gelatin has set, place candies, sprinkles, and food coloring into the petri dishes. Use a toothpick to help swirl and place things.
- Transfer the decorated petri dishes to the fridge to set for about an hour.
Nutritional information is based on third-party calculations, and should be considered estimates. Actual nutritional content will vary based on brands used, measuring methods, portion sizes, and more.