Grow Salt Crystals

This activity requires adult assistance!


  • Epsom Salt
  • Clean Glass Jars
  • Food Coloring (optional)
  • Hot Water, from the tap or microwaved
  • Glass Bowl or Measuring Cup
  • Spoon
  • Pebbles or Sand


You will be using a ratio of 1:1 water to epsom salt for this project.

  1. Add 1 cup of Epsom salt to your jar.

  2. 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.

  3. If you are using food color, add a dash of food coloring to the water and stir.

  4. Pour the water into the jar with the salt.  Stir the salt and water for 1-2 minutes to dissolve the salt.  Don’t worry if some of the salt remains undissolved at the Step

  5. Drop in a pebble or a few grains of sand. 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

  6. Place the jar in the back of your refrigerator.

  7. 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.

Very important Note:

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.

Activity by Rose Mattozo, Sprague Site Coordinator

Photo Credit & Inspiration:

Posted in Activities, After School, Art, At Home, Sprague, STEM.