St. Patrick’s Day Science Experiments

St. Patrick's Day Science Experiments
Explore St. Patrick’s day science experiments that involve gold, rainbows, leprechauns, and the color green.

St. Patrick’s Day science experiments offer a fun opportunity to explore STEM and science involving rainbows, the pot of gold, leprechauns, and everything green. Here is a collection of projects, for both young investigators and more experienced students and adults. Also, learn a bit of the history along the way.

Green St. Patrick’s Day Science Experiments

You see a lot of the color green around St. Patrick’s Day. Informally, green is the national color of Ireland. However, it used to be blue. Blue came into use when King Henry VIII made Ireland a Kingdom in 1542. When George III formed a new order of chivalry for Ireland centuries later, he needed a new color because England’s Order of the Garter used deep blue. Scotland’s order used green. So, the Order of St. Patrick’s color became light blue or “Saint Patrick’s blue.”

Green crept into use more and more over time. It became especially prominent in the 19th century as a way of distinguishing Ireland from the blues and reds associated with England, Wales, and Scotland. Green in the national flag represents the Catholic population, with orange representing the Protestant population, and white standing for peace between them.

For St. Patrick’s Day science experiments, try growing blue-green copper acetate crystals or monoammonium phosphate crystals that look like emeralds (since Ireland is the “Emerald Isle”). Turn flames green, which is the fanciful color of fire in the movie Darby O’Gill and the Little People. Dye a white flower with green highlighter ink and turn on a black light so the flower glows green in the dark.

Shamrock St. Patrick’s Day Science Experiments

The shamrock is one of the symbols of Ireland. Saint Patrick used the shamrock as a metaphor for the Holy Trinity. The word shamrock comes from the Irish word seamróg, which means “young clover.” However, other plants besides clover (Trifolium repens) are also considered shamrocks, such as Trifolium dubium (lesser clover), Medicago lupulina (hop clover), Trifolium pratense (red clover), and Oxalis acetosella (wood sorrel).

As a science project, see what kind of shamrock you find in yards or fields where you live. Collect some leaves and separate out the pigments using paper chromatography to see if shamrocks are only green. If you find more than one plant species, compare them. For children, see if they can identify differences between the plants.

Leprechaun Science Projects

In Irish folklore, a leprechaun is a type of fairy. Some leprechauns are mischievous creatures, others make shoes, and some keep pots of gold at the end of the rainbow. The earliest recorded mention of a leprechaun is in the Echtra Fergus mac Léti (Adventure of Fergus son of Léti). In this tale, King Fergus mac Léti falls asleep on a beach and awakens as three leprechauns drag him into the sea. Fergus turns the tables on them, as he captures them. The leprechauns offer him three wishes in exchange for their freedom.

Leprechauns are solitary beings and may be vengeful if you anger or threaten them. But, if you are feeling brave, perhaps you can trap one in a special batch of green leprechaun slime. Actually, the slime is not sticky, but a leprechaun may be intrigued by its green color. If not, toss in some golden coins as bait. Even if you capture a leprechaun, you’re better off trying for wishes than conducting experiments.

St. Patrick’s Day Gold Science

Later tales of leprechauns mention a pot of gold which a leprechaun hides at the end of the rainbow. Of course, you know that gold is safe, if you’ve ever tried to find the rainbow’s end.

The most popular St. Patrick’s Day gold project is turning pennies into silver and then gold. Really, the project galvanizes copper coins with zinc (silver in color) and then forms the golden alloy, brass.

Another fun St. Patrick’s day science project is turning water into liquid gold. It’s the kind of experiment perfect for a sneaky leprechaun, because it doesn’t make real gold. Instead, it’s a sparkly mineral called orpiment.

Rainbow Science for St. Patrick’s Day

So, the end of the rainbow is where the leprechaun stashes his gold. The obvious St. Patrick’s day science experiment is using a prism and breaking white light into a rainbow. But, there are ways of exploring light and color.

The candy chromatography experiment separates the pigments in Skittles (“taste the rainbow”) or similar candies. The rainbow density project uses sugar solutions of different concentration for making a liquid rainbow. The rainbow wand makes a rainbow in gelatin using a pH indicator, such as universal indicator or red cabbage juice. Float clean nail polish on water and coat paper with a beautiful rainbow. Using food coloring, turn a white flower into a rainbow.

If you’re a bit more adventurous, make a rainbow of colored flames for St. Patrick’s Day!

Green Beer

Green beer is just regular beer dyed with green food coloring. Sadly, there is not a lot of inherent science there. However, you can predict what color drinking the beer turns urine. It’s a science experiment just waiting to happen.


  • Binchy, D. A. (1952). “The Saga of Fergus Mac Léti“. Ériu. 16 (Contributions in Memory of Osborn Bergin): 33–48.
  • Harvey, Clodagh Brennan (1987). “The Supernatural in Immigrant and Ethnic Folklore: Conflict or Coexistence?”. Folklore and Mythology Studies. 10: 26.
  • Koch, John T. (2006). Celtic Culture: A Historical Encyclopedia. ABC-CLIO. ISBN 1851094407.
  • Treeck, Carl Van; Croft, Aloysius (1936). Symbols in the Church. Milwaukee: Bruce Publishing Co.