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20 Minute Labs: Snow Trees

20 Minute Labs salt tree logo | Yellow Scope



winter trees | Yellow ScopeWhen you think of winter, you might picture some beautiful, snow-covered trees.

In this month's blog, you'll use the science of capillary action and evaporation to create some "snow"-covered trees of your own. So even if there's no snow where you live, you can make some indoors to set on your windowsill!

NOTE: Setting up the lab will only take about 20 minutes, but you'll have to wait a few hours or overnight to see the final results.

What You'll Need

  • salt tree supplies | Yellow Scopeflat, non-corrugated cardboard
  • pencil
  • scissors
  • small bowl
  • tablespoon
  • water
  • ammonia
  • salt
  • bluing agent (we used Mrs. Stewart's brand)
  • food coloring (optional)
  • fork
  • spray bottle of water

WARNING: Ammonia fumes are toxic! Ask an adult for help and work in a ventilated area. (You can choose to omit ammonia from the experiment -  it will just take a bit longer to develop and the results will be a little less dramatic.)

WARNING: Bluing agent can stain your clothes, so be careful! (It will not stain your bowl however, as long as it's nonabsorbant - plastic, glass, or glazed ceramic work great!)

NOTE: Plain, noncorrugated cardboard works best, but in a pinch you can use something with a waxy side (like a cereal or cracker box). We used the paperboard sheet from a pack of construction paper.

Let's Get Started!

  1. Using a pencil, draw a small tree on the piece of cardboard. The tree should be about 2-3 inches tall.
  2. Cut out the tree shape, then use it as a template to trace a second tree onto the cardboard. Cut the second tree out as well. You should have two identical tree shapes.
  3. Cut a slit halfway up from the bottom center of one tree, then cut a slit halfway down from the top center of the second tree.
  4. Fit the two trees together so that they intersect and stand up as one. (We made a few different tree shapes for fun!)
    tree cutting | Yellow Scope 20 Minute Labs
  5. To the bowl add: 1 tablespoon of water, 1 tablespoon of salt, and 1 tablespoon of bluing agent.
  6. tree | Yellow ScopeAdd 4 drops of food coloring (optional).
  7. With an adult's help, carefully add 1/2 tablespoon of ammonia.
  8. Use a fork to stir the mixture until the salt is dissolved.
  9. If you'd like, you can color your tree by adding food coloring to the edges of your tree branches. (We made a green tree and an 'autumn' tree with yellow food coloring!)
  10. Using a spray bottle, mist your tree all over to dampen the cardboard. It's okay if the food coloring runs.
  11. Stand the tree upright in the bowl.
  12. Leave overnight. In the morning, check to see what happened!

final trees | Yellow Scope


If you don't see crystals on the outer branches, this may be because the cardboard has dried out. You can use a dropper to draw up some of the liquid from the bowl and squirt it on the drier places on your tree during the evaporation phase.

If you made your tree larger than about 2.5 inches, there may not be enough solution to be effective. Try doubling the solution ingredients, or making a smaller tree.


What's going on?

Did you see a bunch of "snow" crystals on your tree? How did that happen? Well, there's a couple different scientific concepts at play - capillary action and evaporation. 

capillary action | Yellow ScopeIn this experiment, the liquid was pulled up into the cardboard tree by the process of capillary action. Capillary action is the climbing ability of liquids.

For example, water can crawl up tiny tubes that are present in different materials. It does this naturally without any help. Capillary action is how plants deliver water from the soil to their leaves! It's also how water is sucked up into a paper towel. If you are interested in experimenting more with capillary action, check out this capillary action experiment!

Evaporation is also at work here. You may know that water can undergo evaporation, which is the process of changing from a liquid to a gas, (or water vapor). Adding ammonia to the liquid in this experiment speeds up the rate of evaporation.

tree | Yellow ScopeDuring the night, the water and ammonia liquid evaporated, leaving behind the salt and the small particles from the bluing agent. Together they created the beautiful  "snow" crystals you see on your tree!


Let us know what you did. Share your photos and results with us on Facebook, Twitter, Instagram, or send us an email to We love getting your messages!

For more exciting experiments, check out our Yellow Scope Science Kits on the Shop tab of our website!

Chelsea Schuyler
Chelsea Schuyler