Salt Crystal Garden

Grow delicate salt crystal structures on a porous base by wicking a salty bluing solution upward and letting it evaporate. Optional ammonia speeds evaporation, while the bluing particles act as nucleation sites that help crystals form quickly.

1. Choose a shallow, wide container to promote evaporation and place pieces of porous base inside, such as coal, broken brick, terracotta, or sponge.
2. Mix a starter solution and pour it over the base: about 2 tablespoons water, 2 tablespoons table salt, and 2 tablespoons liquid laundry bluing per garden.
3. Allow to sit in open air. On the next day, sprinkle about 2 tablespoons dry salt directly on the top surfaces that are damp.
4. On the third day, slide fresh solution around the edges of the container so it flows under the existing growth, not onto the crystals. Use about 2 tablespoons each of salt, water, and bluing. Add a few drops of food coloring to different base pieces to create multicolored growth.
5. For faster growth in very humid conditions, add up to 2 tablespoons household ammonia to the liquid at the side of the container. Ventilate well and supervise.
6. Maintain the garden by occasionally adding small amounts of water, bluing, and salt at the sides so capillary action can carry liquid up through the base as older liquid evaporates.
7. Observe daily. Record which areas grow first, crystal shapes, and color patterns. Refresh only from below to avoid dissolving delicate structures.

Crystal Garden - Science Beyond:

Salt Crystal Garden - Anne Helmenstine:

📄 Salt Crystal Garden - Mrs Stewart's Liquid Bluing: https://mrsstewart.com/pages/salt-crystal-garden

📄 Grow A Crystal Garden Kitchen Science Experiment (with epsom salt- Science Fun For Everyone: https://www.sciencefun.org/kidszone/experiments/grow-a-crystal-garden-kitchen-science-experiment/

• Compare base materials such as coal, sponge, brick, and coffee filter paper and rank growth speed and coverage.
• Test with and without ammonia and note differences in growth rate under the same room conditions.
• Make a blotter paper tree or shape and stand it in the solution to create a holiday display.
• Vary container geometry. Use a shallow pie plate vs a tall jar to see how air exposure affects growth.
• Try different salt types, such as iodized vs noniodized, and compare crystal appearance.

• Adult supervision required. Keep all materials out of reach of young children and pets. Do not eat any materials or crystals.
• Use household ammonia only in small amounts, in a well ventilated area, and avoid breathing fumes. Wear eye protection when handling ammonia.
• Food coloring can stain surfaces and skin. Protect work areas and wash hands after setup and maintenance.
• Avoid splashing liquids onto existing crystals since they can dissolve and collapse.
• Use only glass or plastic containers that are stable and will not tip. Clean up spills promptly.

• Why does dry air help the crystals grow faster? (Faster evaporation leaves salt behind more quickly, increasing local supersaturation and growth.)
• What role does the porous base play? (Capillary action lifts liquid to the surface where it evaporates, spreading growth across a larger area.)
• How does bluing affect crystal formation? (Bluing contains tiny suspended particles that act as nuclei where salt begins to crystallize.)
• Why might ammonia speed the process? (It increases evaporation and may help the surface dry, which raises supersaturation at the crystal front.)
• Is a chemical reaction occurring? (No. The process is dissolution and recrystallization of sodium chloride aided by wicking and evaporation.)