Intro: Making 9,000 Grow Spheres
The goal was to make 90 centerpieces that would contain these amazing grow spheres that would be centerpieces for a cocktail-esque fundraiser event.
Step 1: Find a Good Fit
Pick out a groovy piece of glassware to display your spheres. Roughly 90-100 jumbo grow spheres fit nicely into one of our large martini glasses. For simplicity we rounded to 100.
Step 2: A Little Math
We then counted 100 dry grow spheres and found their mass to be 5.5 grams.
100 grow spheres = 5.5 grams
 * 100 grow spheres =  * 5.5 grams
9000 grow spheres = 495 grams
For simplicity ~500 grams of dry grow spheres will make ~9000 grow spheres.
Step 3: No Scale?
If you don't have a scale a helpful measurement is that one standard styrofoam coffee cup will hold about 175 grams of jumbo grow spheres.
Step 4: Food Coloring
We went to GFS and picked out some bulk food coloring. Those little bottles you get at the local grocery store are not going to cut it.
Getting the color you want is somewhat challenging since the concentrated food coloring doesn't necessarily reflect the true color. Our goal was to make some blue, orange, and florescent yellow spheres. Blue was easy. We just added a half bottle of food coloring to a small dish and let them soak.
Making orange was slightly more difficult because food coloring only comes in yellow (or eggshell) and red. We started by mixing 400 mL of each together hoping a 50/50 mix would give us orange but ended up needing to add another 300 mL of yellow to lighten it up; in my opinion they were still to dark. My advice is start with a lot of yellow and slowly add red until you get the orange color you want.
Step 5: Florescein
We have access to some raw florescein from our chemical lab to make the yellow grow spheres. You can order it from most chemical supply stores and it is safe to handle. Another option would be to smash highlighters and squeeze the liquid from the center into a bowl. You would probably need a lot of highlighters.
If you are using (and you probably should be) the chemical florescein a little goes a long way but you want to start out with a small container of water and add enough that the liquid turns a deep, almost amber, yellow. You will then water it down from this concentration.
Step 6: Soaking in Small Containers at First
You want to have them absorb as much of the coloring as possible at first so dump your dry grow spheres into small shoe box sized containers with just the food coloring. Slowly add water as they absorb the color. You'll see little bumps form on the surface of the water when it's time to add water.
Step 7: Transfer to Larger Containers
Eventually the shoe box size container will not be large enough and you'll have to transfer your spheres. This happens surprisingly quickly considering all 9000 of those spheres absorb 800 times their mass in water.
Step 8: Strain Your Spheres
After about a day the spheres will reach their maximum size. At this point you want to strain and rinse them off with water. We used a giant pasta strainer to do this. If you neglect this step then the spheres will die your hands a little when you touch them.
Step 9: Start Filling Your Glassware
We had two different types of glassware loosely designed to look like giant drink glasses. By complete coincidence they both needed about 100 grow spheres to fill them.
Step 10: Add Lights
We picked up these led ice cubes to light up our displays. They have a bunch of different settings but blinking was the obvious choice.