It's a mixture that your tree sits in.
To make it:
-2 cups of Karo syrup
-2 ounces of liquid chlorine bleach
-2 pinches of epsom salt
-1/2 teaspoon of Borax
-1 teaspoon of chelated iron
-2 gallons of hot water
Mix all ingredients in a 5 gallon bucket.
Make a fresh cut one inch from the bottom of the tree, and place it in the mixture for 24 hours.
Place the tree in its stand, and add more of the mixture, topping it off each day.