Making Rock Candy

I had a fun opportunity to have a couple extra children in my home today. One of them is another Kindergartner, who is full of curiosity and energy, just like my Kindergartner. When I told them that we were going to plant some candy today, they both got an amazed look on their faces. Making rock candy isn’t about the recipe, so much, but more about the wonder of crystals and watching them grow.

 Making sugar crystal candy |

On the way back from school, I told the kids that some candy needs to be planted. And while we all laughed – and they were sure I was crazy – their excitement and enthusiasm for the project was infectious.  While they were busy playing and talking about planting candy, I washed out some mason jars to make sure they were clean and ready for our experiment.

We started by making our seed crystals. I’ve made sugar crystal candy before using a string, but wanted to make the sugar crystal candy on a stick this time. The sticks will let my visitor take his candy home and enjoy it later.

Seed crystals are made by soaking bamboo skewers for a moment in water and then rolling them in sugar until well coated.

I explained that crystals form in square-like shapes and need a square to grow on, and putting the crystals on the sticks will help the sugar stick where we wanted it to. (Not a very technical explanation, but it satisfied their questions.) We also explored the shape of the sugar crystals by examining them closely, and also by rolling the sugar between our fingers. I asked the children these questions:

Does the sugar feel smooth or hard?
Can you see the shape of the sugar?
Do the sugar crystals have flat surfaces or round surfaces?

After we had made the seed crystals, it was time to make the super saturated sugar solution.

Add one cup of water to a sauce pan, and bring it to a boil.
Next, add two cups of sugar – ¼ cup at a time. The sugar could completely dissolve into the water.
Candy flavoring and food coloring can be added at this time.

 Making sugar crystal candy |

We added red and blue food coloring, to make purple.  We couldn’t decide on which color to make, so we added both colors that the children wanted. We also added orange flavoring, so we’ll end up with orange flavored, purple rock candy when we’re all done.

After we added all the ingredients we stirred the solution until all the sugar had dissolved. After the sugar had dissolved, it was time to add the solution to the mason jars. I took over the experiment at this time. I’m not a big fan of five year olds putting hot sugar syrup into mason jars.

 Making sugar crystal candy  |

Be careful when adding the syrup to the jars, the solution will be very hot and sticky. I recommend using a pot holder to hold the jar if possible.

Now, add the seed crystals.

I called the children back and told them it was time to plant the candy seeds. Again, they thought I was silly, but they were excited to place their seed crystals into the jars. I moved the jars to a place where they shouldn’t (I hope) be bothered.

We’ve waited for about eleven days and had several great crystals come from the experiment. We also found out that adding food coloring to the water didn’t color the crystals. We’re not completely sure why, but think it has to do with how the sugar crystals form.

 Making sugar crystal candy  |

Mama Smiles also made sugar crystals with her kids.  You can read about her experience here: Growing Sugar Crystals: Delicious Science for Kids.


  1. Kurt Kroh

    We did this when I was a kid. It was very fun and educational. Thanks for another great post.


    1. Thanks so much for reading my posts. I’m so glad you enjoy them. I’ve actually tried to grow sugar crystals several times — even with Weblos when I was a leader — with absolutely no success. I’m glad I finally had some work out. :) Practice and perfect, or something right.
      Thanks for visiting and commenting, my friend.


  2. Deborah, I did this as a kid with the string, but not the seed crystals. I want to do this with my grandkids. So do I put the bamboo that is coated in the granulated sugar completely submerged in the mason jar of hot sugar water and then cover it with a cloth to keep the dust out for 11 days I am excited to make this with them. THANKS for the fabulous post!!!!


    1. Yes. The bamboo seed crystals need to be submerged in the hot syrup. The crystals won’t climb up the bamboo, so what is outside of the solution isn’t going to grow any crystals. And if you cover the jar with a paper towel, you can just push the bamboo through the towel. That way the sugar solution/seed crystals aren’t disturbed very much.
      I really hope your grandkids enjoy the activity and that all goes well. The hardest part for me was not touching the jars for so long. Patience has never been one of my strong suits.

      Thanks for the comments. :)


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