How to Grow a Charcoal Crystal Garden

Grow a chemical crystal garden using laundry bluing, salt and ammonia.
Anne Helmenstine

Make delicate, colorful crystals! This is a great classic crystal-growing project. You use charcoal briquettes (or other porous materials), ammonia, salt, bluing, and food coloring to grow a sort of crystal garden. The components of the garden are toxic, so adult supervision is recommended. Be sure to keep your growing garden away from young children and pets! This can take anywhere from 2 days to 2 weeks.


You only need a few materials for this project. The key ingredients are ammonia, salt, and laundry bluing. If you don't use food coloring, expect the crystals to be white and clear. With the coloring, remember some colors may bleed into other to give a watercolor effect.

  • Charcoal Briquettes (or pieces of sponge or brick or porous rock)
  • Distilled Water
  • Uniodized Salt
  • Ammonia
  • Bluing (shop online)
  • Food Coloring
  • Non-Metal Pie Plate (glass is great)
  • Measuring Spoons
  • Empty Jar


  1. Place chunks of your substrate (i.e., charcoal briquette, sponge, cork, brick, porous rock) in an even layer in the non-metal pan. You want pieces that are roughly 1-inch in diameter, so you may need to (carefully) use a hammer to break the material up.
  2. Sprinkle water, preferably distilled, onto the substrate until is has been thoroughly dampened. Pour off any excess water.
  3. In an empty jar, mix 3 tablespoons (45 ml) un-iodized salt, 3 tablespoons (45 ml) ammonia, and 6 tablespoons (90 ml) bluing. Stir until the salt is dissolved.
  4. Pour the mixture over the prepared substrate.
  5. Add and swirl a bit of water around in the empty jar to pick up the remaining chemicals and pour this liquid onto the substrate, too.
  6. Add a drop of food coloring here and there across the surface of the 'garden'. Areas with no food coloring will be white.
  7. Sprinkle more salt (about 2 T or about 30 ml) across the surface of the 'garden'.
  8. Set the 'garden' in an area where it will not be disturbed.
  9. On days 2 and 3, pour a mixture of ammonia, water, and bluing (2 tablespoons or 30 ml each) in the bottom of the pan, being careful not to disturb the delicate growing crystals.
  10. Keep the pan in an undisturbed place, but check on it periodically to watch your very cool garden grow!

Useful Tips

  1. If you can't find bluing at a store near you, it is available online: (Mrs. Stewart's Bluing).
  2. Crystals form on the porous materials and grow by drawing up the solution using capillary action. Water evaporates on the surface, depositing solids/forming crystals, and pulling more solution up from the base of the pie plate.
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Your Citation
Helmenstine, Anne Marie, Ph.D. "How to Grow a Charcoal Crystal Garden." ThoughtCo, Apr. 5, 2023, Helmenstine, Anne Marie, Ph.D. (2023, April 5). How to Grow a Charcoal Crystal Garden. Retrieved from Helmenstine, Anne Marie, Ph.D. "How to Grow a Charcoal Crystal Garden." ThoughtCo. (accessed June 5, 2023).