I love those moisture crystals! I put a Black-Stem Taro (gift from a friend) into my "tropicals" bed this spring and put an extra-big dose of moisture crystals at the bottom of the planting hole. It grew 7 feet tall with huge leaves, and the bulb (corm?) is about 3 times the size I started with. :-)
They're also life savers for containers in full sun. Without them, twice a day watering wasn't enough... with them, I can even skip a day unless the temperature is up in the 90's or above.