Hi Linnea,
You should be able to find those polymers in any nursery or possibly nursery section of Lowes, Home Depot etc. I've only used Soil Moist, with great effect, but there are other brands out now. Make sure you mix it deeply into the potting soil at the root level. I was surprised and mystified to see glistening slimy things on top of some dahlia pots last year- but instead of the slug eggs I suspected, it was only jello cubes of stray Soil Moist granules. A pleasant surprise for a change!

Here is a link that might be useful: About Soil Polymers

Hi Linnea, I use them too! BUT..I soak them first then add them to the soil. Dry, they are very tiny, so wetting them first is helpful in knowing how much to use.

I've used Shultz Moisture Plus Watering Crystals, they used to sell it at Wal-Mart and Soil Moist, which is sold at Pike here in Atlanta GA. I use the crystals for my Window boxes and it keeps my plants alive. Other than that , they would surely die, because my boxes are up high and the heat is relentless. You only need a tiny bit for each plant or else you will have a ton of jelly like beads all over the place that will eventually surface.