Ann Reardon

Rock Candy Recipe How To Make Large Sugar Crystals

sugar rock candy large crystals

Large sugar crystals on lollipop sticks, otherwise known as rock candy is a fun experiment to make at home with the kids.   You don’t need many ingredients but you will need some patience as they take a few days to form.

Rock Candy Ingredients

3 cups or 648g (22.86 ounces) sugar
1 cup or 250 millilitres (8.45 fluid ounces) water
lollipop sticks

Fill a thermos flask with hot water and leave to sit.

Combine all ingredients in a saucepan and heat until a spoonful lifted up looks clear.
Empty the thermos flask and pour in the sugar solution. Cover the top with a double layer of aluminium foil and then poke your lollipop sticks down into the center.
Try not to disturb the sticks, watching them grow is half the fun so go on have a quick look once a day. And after four or five days you will have some nice chunky sugar crystals.

rock candy big crystals
You may have seen other tutorials that tell you to pour the sugar solution into a glass, if you do that the solution cools down quickly forcing the sugar to crystalize fast into lots of little crystals. The image above shows the large crystals made in a thermos at the top and smaller ones made in a glass at the bottom.

You might also like rock candy geodeshow to make rock candy

by Ann Reardon How To Cook That

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All recipe quantities in the book are in grams, ounces and cups.

36 Comments View Comments

  1. Rating: 4.5


  2. Hello Ann, I have been asked to make a geode cake that is in total going to be about 40cm tall. The geode part is quite big. How do I make sure I have enough rock candy?
    Thank you for your help and tutorials
    Kind regards Jodie

    • Hi Jodie, THat is so difficult to answer. It will depend on the look you are after. I recommend that you make mmuch ore than you think you will ned so you can decorate liberally and have a good range of crystals to choose from.

      • Thank you for your response. I had totally forgot that I asked. 🙂

  3. I have a ton of crystals at the bottom of my thermos. How can I get them out? Are they a complete loss and I just have to wash the thermos out?

    • Hi Laine, You could try standing your thermos in hot water and then lift/scrape them out using a longe handled teaspoon.

  4. I followed the recipe exactly as Ann said, but after 4 days when I took them out to check, there where no crystals on it al all.

    • Hi Nathan, That suggests that either the sugar syrup wasn’t concentrated enough or the sugar wasn’t properly dissolved. Try again paying attention to your quantities etc. You can also dip the lollipo stick into the syrup then into a ver small amount of crystal sugar then pop it back into the solution. This sometimes kick starts the process.

  5. Great advice about the thermos! I always wondered why my crystals never get as big as the ones I buy. Thank you!

    • After reading a few other comments; People may want to try “casters sugar”. It’s just a superfine grain sugar that dissolves more quickly. The crystals will not lose any size and they will look more glassy.

  6. Hello! I tried this recipe but… nothing happened! No crystals at all. After 3 days, it’s still only a syrup. What did I do wrong? Do I have to waste everything now? It makes me so sad!

    • Hi Paola, It will likely be one of two common problems. Either the sugar wasn’t till properly dissolved or the concentration of sugar was a little low. Some followers have found that the sugar they use just isn’t as ‘sugary’ and they needed to add more to get the crystals forming. The concentration given in the recipe should be plenty strong enough to get the crystals forming. Another tip a follower passed on was dipping the stick in the syrup then into a little crystallized sugar and then sitting them back in the solution. This helps to seed the crystals so to speak. I haven’t tried that but it is worth a go.

      • Thank you so much for the answer. 🙂

  7. the I’ve wanted to make these for so long then I stumbled across this recipe on YouTube thank and I love your vids without you I would not be baking for my family (I’m 11)

    • i bake to look at this picture


  9. Hi Ann, for the geodes, do you have to add colouring to get the flavour?. Thx❤️I luv your cooking abilities!

    • Hi Sam, To create a particular flavour, you will need to add suitable flavours. I didnt add flavour, I just left mine plain.

  10. This is are science projects……it’s really fun to make.

  11. Hi Ann,

    Does that mean you will only make two rock candy stick at a time? I want to make a lot for a birthday party… Thanks!

    • You can make more, it just depends on how much space you have in the mouth of your thermos.

  12. I love it so delius

  13. Hi Ann,

    Just found your website, I just love it. Going to make chocolate cake, and the macaroons.

  14. ta thats great you make such wonderful stuff.. x

    • 😀

  15. Hi there,

    I love what you do its really great and you make it so easy for me to cook.
    I was wondering if its not too much trouble can you put the recipes in one page and make them into pictures so that I would save them on my desktop I just find it easier to look up when I need a recipe or put them in a link as a PDF file and we could download them all at once with pictures.

    best regards and all the best

  16. Hi, other tutorials say that if you see no formations at all with 2-3 hours, that you should reboil the mixture and add more sugar….
    Also, other tutorials say to be careful that the string (I am using a skewer) doesn’t touch the bottom….
    And finally, other tutorials say to bring the water to a boil, dissolving one cup of sugar at a time, then add flavorings/colors….
    What do you think about those instructions? Do they change the outcome?

    • Hi Joanna, as we are making larger crystals they do take longer to form, though you will start to see a coating on the sticks in a few hours as shown in the video. The crystals will still form if they touch the base, though they can stick to the base and then crystals crack off on removal.

  17. Hi Ann,

    Can I have your e-mail address please?

    thank you

    • Hi Anne you can contact me through comments section here or if you would rather you can go to the howtocookthat youtube channel or facebook page and send a message there.

  18. A cheap version of those sugar sticks that you buy to stir your coffee with, and it will work with brown sugar too. great idea. Thank you.

  19. I am very much eager to see my kids faces when I make and give it to them.they would be very much excited

  20. Awesome,always loved your videos

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