Any exploration of science for kids is not complete without growing some crystals….am I right? In fact, at the science fair this past year crystal growing projects were the project de jour, and I can understand why, growing a Crystal Garden has ranked pretty high up there on my list of fun science experiments since I myself was a kid!
Now one of the big drawbacks to many crystal growing projects is the time involved. I’ll be honest, I am not a patient woman and though I proselytize patience to my kids, I’m not a very good example of this virtue! So days of waiting for a crystal garden to grow pretty much sent this idea to the “someday” list. That is until I discovered Epsom salt crystals….leave them overnight and wake up to magic! Oh how much do I love thee Epsom Salt!Grow crystals overnight in your refrigerator!Click To Tweet
To be fair, growing crystals using Epsom salt will not yield giant geodes bursting with color; Epsom salt crystals are small, delicate, and slivery. Instead of one or two mega crystals this science experiment for kids will give you hundreds of miniature crystals, they look a little bit like shards of glass and if you’re lucky you may get a few that look like snowflakes…We experimented quite a bit with this project to get good results and despite repeating the process exactly the same we had about a 70% success rate with crystal growth each batch we made. So plan on making 3-4 crystal gardens in case 1 or 2 don’t grow. Another upside to making a few gardens at once is seeing how differently they grow, some crystal gardens were delicate and lacy, other were more rocky and gem like. Be sure to make a bunch to delight you and the kids!
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Science for Kids: Overnight Crystal Garden
- Epsom Salt
- Clean Glass jars or round glass votives like these
- Liquid Watercolors (optional) Note: these are concentrated so a little goes a long way; these are one of the best art supplies you can invest in!
- Bowl or glass measuring cup
- Microwave (optional)
- Step One | Measure You will be using a ratio of 1:1 water to Epsom Salt for this project. Add 1 cup of Epsom salt to your jar/votive. If you are working with larger jars feel free to add more salt but be sure to make a note of how much so you can add the same amount of water.
- Step Two | Heat the Water Add 1 cup of water to a microwave safe bowl. Heat the water in the microwave for 45 seconds. Alternatively use very hot tap water and skip the microwave.
- Step Three | Add Color If you are using color, add a dash of liquid watercolor to the water. Stir.
- Step Four | Combine Pour the water into the jar with the salt. Do this quickly so that the water is warm. Stir the salt and water for 1-2 minutes to dissolve the salt. We stirred for 2 minutes on most of our experiments. Don’t worry if some of the salt remains undissolved at the bottom of the jar.
- Step Five | Cool Place the jar in the back of your refrigerator. Alternatively, quick cool the mixture for 10 minutes in the freezer and then move it to the refrigerator. Cooling in the freezer first yielded crystal growth in 90% of our experiments. We had just a slightly lower success rate going straight from mixing to the fridge.
- Step Six | Let ’em Grow Leave the mixture overnight in the fridge. Crystals may start forming in as little as 3 hours but we got the best results when we made the gardens in the evening and left them to sit undisturbed overnight Bonus: My daughter was excited to wake up and see how they had grown!
- Step Seven | Result Time Carefully pour out the extra liquid. It’s okay to leave a little liquid at the bottom of the jar. If you colored your water it will be hard to see if any crystals have grown until the excess liquid is removed. Clear water is easy to check.
- Step Eight | Clean Use a wet paper towel to gently wipe away excess salt and color that may be on the upper portion of the jar. This will help you see the lovely crystal garden through the glass. Be careful not to damage any of your crystals!
You’re done! Hand the kids a magnifying glass for additional exploration. My kids really wanted to touch the crystals. That’s okay but let them know they are delicate and break easily.
Science for kids is not without trial and error! Here are some tips I learned after repeating this experiment over 20 times…
- There will be duds. I did this experiment many, many times, mixing up some of the variables, but the only constant was that I always had a few instances where the crystal would not grow. I’m not a chemist and I’m sure there is a reason why one mixture grew and another did not despite me thinking I had done the exact same experiment….So hedge your bets and make a few of these at one time. UPDATE: A few scientists have replied to this post and recommend dropping a grain of sand in each batch. Crystals need something to grow on and one little impurity in the water like grain of sand will should help ensure they have a place to nucleate.
- Don’t overheat the water! I know it’s tempting to really heat that water up to make the salt dissolve, but all the experiments we did with really hot water, heated more than 45 seconds in the microwave, failed miserably. Trust me, DON’T DO IT!
- Stir for at least one to two minutes! This is tough one for littler kids. My daughter was done stirring within a few seconds but you really need to get that water super saturated with salt to make the crystals grow. The less dissolved the salt is the smaller the crystals will be and worst case they may not grow at all.
- Let them grow even longer in the fridge. Leave them in the fridge longer than overnight and they should continue to grow. I left a few in the fridge for a over a week and the results got even better!
- DO NOT let them sit in water at room temperature. Any crystals that have formed will deteriorate in the water at room temp. Once the crystals have formed and you want to preserve them you will need to pour out the water. I had some gorgeous crystals form in the fridge over the course of a week or so and I took them out and left them on the counter in the water. I came back the next morning to find they had flattened out. The one garden I poured the water out of remained stunning.
- Make a Crystal Suncatcher with the leftover water!
Carlsbad Caverns. Have you been there? I was lucky enough to go there many, many years ago and it is as impressive and wondrous as you can imagine. I mean who wouldn’t be floored by descending into a bat filled cave to see huge stalactites and stalagmites? If you are ever in south eastern New Mexico you must make a trip there! For more local sightings, those of you in California can visit Mitchell Caverns in the Mojave Desert.
Well that was fun, right? Here’s a little something you can try with the leftover saturated water: Make Crystal Suncatchers:
Making Epsom Salt crystals is really simple and a great idea for a science fair project!
For more fun science experiment ideas for kids hop over here
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