How to Make a Crystal Garden for a Science Project
I was recently introduced to growing a salt crystal garden by a friend of mine. She had beautiful cauliflower-like blooms growing in a dish on her countertop. Once I saw it, I decided that it was a must-do project for the kids and me. I had most of the items I needed to grow the garden lying around the house, and the time spent to make it was minimal. It is so easy, but yet so satisfying to watch the crystals in the garden grow.
This would be great for kids looking for a science fair project, but even without the science fair, it’s fun. My kids were mesmerized by the growing crystals and seeing how they changed each day. So without further ado, here are instructions on how to make your own salt crystal garden.
- Mrs. Stewarts Bluing (find this in the laundry section of the store)
- Warm Water
- Container to grow crystals (glass or plastic work well)
- Food Coloring (optional)
Wet the sponges and squeeze them out. Next, cut the sponge into small sections that are about an inch or two big. Then place the individual sponge pieces into the container you’ll use to grow your garden. It depends on the size of your container how many pieces you use. Our containers each had one sponge in them. We tried to get creative with the building the base of our garden, but to be honest, the gardens with sponges stacked on each other took longer for the crystals to form. Crystals still grew, but the results were a bit slower.
Next, for each crystal garden take 2 tablespoons of salt, ammonia, liquid bluing, and warm water and combine them in a measuring cup. Stir until you can no longer get the salt to dissolve. All of the salt won’t dissolve, so don’t try. Just mix it until you feel it’s as dissolved as it’s going to get.
After the solution is combined, pour it over the sponges. When you get to the mucky blue salt at the bottom, drop it on top each of the sponges. Make sure to use all of the mixture.
If you’d like to use food coloring, now is the time. A few drops here and there on top of the salt blobs will suffice. We found that blue worked best. Green turned teal blue, and red and yellow really didn’t leave a color at all. If you don’t use food coloring the crystals will be white which is quite stunning.
I’m not exaggerating when I say the crystals will begin blooming within the hour. The overnight results are amazing.
Add two more tablespoons of salt to the places on the sponges that crystals didn’t form. The crystals will continue to form throughout the day.
Day Three and Beyond
Prepare a half batch of the original mixture and pour it into the bottom of the container. This is the food that will keep the crystals blooming. You can continue to add the mixture every few days and your crystal garden will grow for in infinite amount of time. Ours grew for over 3 months until we decided we our needed the counter space back.
Crystal Garden Hints and Tips
- The crystals are very fragile. They will collapse if you touch them. They may collapse when you move them. No worries though, they will grow back when you “feed” your garden.
- You can add food coloring at any time, but it will dissolve your crystals. The good news is they will grow again each time you add more of the ammonia, salt, bluing mixture.
- Ammonia is not needed to get the crystals to grow. It actually just aids in the evaporation process. Leave ammonia out if you wish, but realize it will take longer for the crystals to form.
- After days of feeding your garden it may begin to try to escape your original container by growing up the sides. That’s ok, just put the container inside a larger container like a cake pan.
- Don’t be afraid to experiment with the crystals. After months of feeding the crystals we tried to kill them off by just adding water, instead of the solution. Guess what, they still grew back for days.
- Any porous substance can be used instead of sponges; charcoal or lava rock would make a good substitution.
- Air needs to flow freely around the crystal garden for it to grow, so don’t cover it up.
The Science Behind the Crystal Garden
Soluble – easily dissolved, especially in water.
Crystalize – to change from a liquid to a solid form that is made up of crystals.
Evaporation – to change from a liquid state to a gaseous state.
Colloidal Suspension – A substance where the particles of the solution are mixed, but they are not dissolved.
Porous Substance – Any substance having small spaces or holes through which air or liquid may pass.
Capillary action – The ability for liquid to travel through small spaces without the help of forces like gravity.
Now that you know the science terms here’s how they apply to the salt crystal garden. First off, salt is a soluble crystal, therefore, it’s a crystal that can be dissolved in water. In any salt and water solution when the liquid evaporates the salt will crystalize. Think of a saltwater fish tank, in all saltwater fish tanks a white powdery crystal substance can be found at the top. This is because water in the tank has dissolved leaving salt crystals at the top of tank. You can test this for yourself by dissolving 1 teaspoon of salt in one cup of hot water. After a few days, some of the water will evaporate and white crystals will form at the point where the water originally started.
In the recipe for the crystal garden large amounts of salt are added in proportion to the amount of liquid. You can see this just from the fact that when mixed it is impossible to get all of the salt to dissolve.
Because there is so little liquid, the crystals will form quickly. The Mrs. Stewarts bluing acts as a colloidal suspension in the mixture. Since the bluing particles are not dissolved, they form the nucleus of the crystals and allow the salt garden to bloom around it rather than form chunky solid salt crystals.
As mentioned earlier, the ammonia aids in rapid evaporation. It not only evaporates quickly, but it also helps the water and liquid bluing to evaporate quickly.
On day three and beyond you should add the mixture to the bottom of the container. This helps keep the crystals from being disturbed. Because the sponges are porous, the mixture will be drawn up through the sponges by capillary action. This feeds the crystals, and keeps them growing for months as long as you remember to feed them. If you don’t feed them, the crystals stay for a while, but their appearance changes dramatically.
So whether you are planning your next science project, or just want to have fun growing a crystal garden this project is a must try.