One of my favorite things to do as a kid was to grow "Crystal Gardens." The first time I did it was in a Sunday School class; the teacher found the instructions in a little booklet tied to a jar of laundry blueing. This is a super activity for a rainy summer day with your kids. You can build a single garden together, or, if you've got multiples or the neighbor kids, they can each make small individual gardens.

Things You Need

• A glass or ceramic dish (not metal, and nothing precious)
• Several pieces of charcoal briquette, bricks, or small pieces of porous rock, that are roughly an inch in diameter. This is the medium upon which your crystals will grow.
• A clean empty glass jar
• Salt (table salt is fine; salt without iodine is slightly better)
• Blueing (look in the detergent section of the grocery store)
• Ammonia
• Food coloring

Procedure

1. Rinse the material you'll use for a growing medium in water. You want it to be damp but not soaking in water.
2. Arrange the medium in the bottom of the glass dish. It doesn't have to be in a single layer; feel free to be a little creative.
3. Mix the following in the glass jar:
   • 3 tablespoons Salt
   • 3 tablespoons ammonia
   • 6 tablespoons bluing
4. Mix or gently shake until the salt is dissolved.
5. Pour the solution over the medium in the glass dish. Try to saturate all of it with the liquid.
6. Rinse the jar out with a tablespoon or so of water, and pour that into the dish as well. Set the jar aside; you'll need it again.
7. Carefully put drops of food coloring on the medium; anyplace that you don't add food coloring to will have white crystals. Remember that yellow and red makes orange, blue and red purple makes purple.
8. Sprinkle an additional two tablespoons of salt on top of the medium.
9. Place the dish someplace where it won't be disturbed, out of the reach of pets and small children.
10. On the second and third days, pour a solution of 2 tablespoons of salt, 2 tablespoons of ammonia, and 2 tablespoons of bluing into the bottom of the dish. You need to be a little delicate in doing this, since there will be tiny crystals already.
11. The crystals will grow for several days, then stop. They are very delicate, and will crumble if disturbed.

You'll see crystals start to form just a few hours after you add the solution. What happens is that capillary action draws the solution up through the coal, where the liquid evaporates, leaving the crystals behind. You can engage in variations on this theme, as well; you can make trees out of thick blotter paper; make two trees, and split one down the middle, vertically, half way down the top, and the other halfway up from the bottom; intersect the two trees to make a three-dimensional tree. Color the tips of the branches with colored markers, then place the tree in the solution. This is essentially the way the "Magic Tree" works.