How to Grow a Urea Crystal Flower or Tree

This entry was posted on by (updated on )
How to Grow a Crystal Flower or Tree
This urea crystal flower or tree grows while you watch, within minutes. It’s an easy project that’s safe for kids of all ages.

The urea crystal flower or tree is a safe crystal-growing project that yields results in minutes. Crystals actually grow as you watch! The delicate crystals growing on paper resemble flowers on a tree or petals on a flower. Here’s what you do:

Urea Crystal Flower Materials

All you need is urea, water, clear school glue, dishwashing liquid, and a coffee filter. If you like, add food coloring for colored crystals.

  • Urea (carbamide) – CO(NH2)2
  • Water – H2O
  • Clear school glue (contains polyvinyl alcohol) – [CH2CH(OH)]n
  • Dishwashing liquid – detergent
  • Food coloring (optional)
  • Paper coffee filter (or tissue paper or paper towel)
  • Small dish

Urea also goes by the name of carbamide. It is not toxic, but it can irritate skin. If you touch the chemical or the crystals, rinse off your hands. You may find it in a gardening store as fertilizer, but it’s readily available online. It is fairly inexpensive (around $10 per pound of pure chemical).

Ordinary tap water works fine for this project. Use clear school glue. This type of glue contains polyvinyl alcohol (PVA), which helps give the crystals a fluffier structure rather than the usual needle-like shape of pure urea. It’s fine if you use translucent colored glue or if it contains glitter. Any liquid dishwashing liquid is fine. I used Dawn because that is what I had. The detergent helps the crystal-growing solution flow through the paper.

Any porous paper works. A paper coffee filter is ideal. But, if you are crafty, feel free to use tissue paper flowers or make tree shapes using paper towels, construction paper, or even cardboard.

How to Grow Urea Crystal Flowers

  1. Dissolve urea in a small amount of water. Urea is highly soluble, which means a lot of it dissolves in a small amount of water. To avoid wasting the chemical, start with a half cup of hot water and stir in urea bit by bit until no more dissolves. Another variation uses 3 teaspoons hot water and 2 tablespoons urea.
  2. Stir in a squirt of clear glue (1/3 to 1 teaspoon) and a few drops of dishwashing liquid. Add food coloring, if desired.
  3. Pour this liquid into a small container that holds your paper tree or flower.
  4. Prepare your paper shape. Experiment with tree and flower forms. For a Christmas tree, set the coffee filter cone in a small dish so its point faces up. For a flowering tree, snip “branches” around the edge of the paper, roll or twist it, and place it in a small container with the branches extending outward. (I used a shot glass to hold the “tree”.) For a flower, fold and cut the paper into a shape and set it on a shallow dish.
  5. Set the project somewhere with no drafts or vibrations. Crystals grow within minutes and are very fragile. As the crystals grow, eventually their weight causes some to fall. Crystals continue growing until all of the liquid is gone.

If you have a magnifying glass, inspect the crystals. When you’re done, clean up using warm water.

If you enjoy this project, try growing other crystals. A similar project uses laundry bluing, but the crystals look a bit different.

References

  • Meessen, Jozef (2012). “Urea”. Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a27_333.pub2
  • Yalkowsky, Samuel H.; He, Yan; Jain, Parijat (2016). Handbook of Aqueous Solubility Data. ISBN 9781439802465.