A chemical garden is a beautiful and classic chemistry demonstration where vividly colored, plant-like structures grow spontaneously in water. Here’s a clear description of the setup and process:
Chemical Garden Setup
Materials Needed
A clear glass beaker or tall jar
Water (distilled works best)
A small amount of sodium silicate solution (water glass)
Crystals of metal salts (such as copper sulfate, cobalt chloride, nickel sulfate, or iron(III) chloride — each gives a different color)
Procedure
Fill the beaker with the sodium silicate solution.
Drop in a few small crystals of the chosen metal salts.
Almost immediately, colorful, branching structures begin to sprout from the crystals and rise through the liquid, looking like underwater plants or corals.
Why it Happens
The metal salt reacts with silicate ions in the solution to form an insoluble metal silicate membrane around the crystal.
This membrane is semi-permeable: water flows in by osmosis, building internal pressure until the membrane ruptures.
The rupture allows more salt solution to leak out, which reacts further with sodium silicate, forming a tube that grows upward.
The cycle repeats, producing branching, tubular, and often helical or feathery “stalks”.
Different metal salts create different colors:
Copper sulfate → blue-green stalks
Cobalt chloride → purple or pink stalks
Iron salts → brown or orange stalks
Result
The beaker soon resembles a miniature underwater garden, with delicate stalks and blooms of many colors. This is why it’s called a chemical garden.