Lemon and Watercolor Science

Of all the art and science projects that I have done, lemon and watercolor science has been my #1 fave for YEARS! It’s a dazzling sensory activity that you can never get enough of.

A hand squeezes a lemon half above a paper painted with colorful watercolors. Next to the paper sits more watercolors and several lemons cut in half.

I discovered lemon and watercolor science years ago, and it was love at first sight

The first time I did this project was with my preschoolers, and the mood was electric.

This project has it all:

It smells good.
It’s fun to look at.
New colors blend right before your eyes.
It’s messy and unpredictable and just outstanding.

In fact, I loved it so much that I had to show my college students that night, too. So I walked into class with a giant bag of lemons, my arms full of watercolors, and said, “There’s no time for a quiz tonight because it’s science time!”

And guess what? The college students were just as enamored with the project as the preschoolers. It’s everything.

Related: looking for more Science activities for kids? Our Virtual Preschool program is designed for teachers and preschool homeschooling families and is loaded with Science (+ much, much more!).

A close up of lemon and watercolors mixing together in cool colors (green, blue, lime, and purple).

We do lemon and watercolor Science throughout the year

Because we do so many lemon activities, we are often gifted bags of lemons from people who have trees that overproduce.

This means we’re the lucky recipients of lemons throughout the year. This project belongs to no specific season, so we make lemon volcanoes in February, June, October, and every month in between.

I always joke that friends with lemon trees are the best kinds of friends. 😂

Looking for more lemon activities? These are fantastic:

Materials

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Lemons
Watercolors – here we used liquid watercolors, but pan watercolors work, too
Thick paper – if you don’t have watercolor paper, use the thickest paper you have on hand (like cardstock)
Paint cups – optional, but included here because people love them when we use and show them!
Thick paintbrushes
Lemon juicer – optional, just for extra fine motor fun

A piece of white paper is painted with stripes of watercolors. Working from top to bottom: teal, dark green, purple, lime green, pink, and orange.

Directions

This activity is simple: get a LOT of paint on your paper, then drop on lemon juice.

I used liquid watercolors here (and prefer using them over pan watercolors) because it’s easy to get a paper saturated with wet color. You want your paper to be soaked before adding the lemon juice.

I have two strategies to get my paper extra wet: (1) use thick paintbrushes as they hold more color and get your paper wetter faster, and (2) paint quickly!

Once your paper is wet, shiny, and colorful, squeeze on your lemon juice.

When the lemon juice touches the paints, you’ll see an immediate reaction. This is the very best part.

If using liquid watercolors, pay special attention to when the lemon juice touches the orange paint. For most of the colors, lemon juice lightens the paint color. But, for orange, the lemon juice makes it turn red! Very cool.

A hand holds a green citrus juicer and squeezes lemon juice onto a painting.

Video Tutorial

What does lemon juice do to a watercolor?

Lemon juice has several things in it, including water, sugars, vitamins, and citric acid.

When the citric acid touches the watercolor paints, it has an immediate “bleaching” effect.

You’ll see this reaction right before your eyes! The colors change, mix, blend, and transform as the lemon juice touches and interacts with the watercolors. We love observing scientific reactions.

A close up of lemon and watercolor science where colors are blended together and some lemon seeds are stuck to the paper.

Questions to ask your child during lemon and watercolor science

“What do you predict will happen when the lemon juice touches the watercolors?”
“Why does the lemon juice change the color of the paints?”
“What else could we add on top of watercolors to make the same effect as the lemon juice?”
“Can you describe the lemon – how does it look, feel, smell, taste?”
“What happens if we try adding lemon juice onto a dry painting?”
“What else can we do with lemons?”