I've had some for a couple of years and used in containers but last year began to build raised beds. I added these crystals to the beds which were built in wintertime. All through last summers' drought, I looked for the polymer in the beds and didn't see any but the plants survived fairly well in spite of the tough summer.
Building another bed this spring and I added them without rehydrating. We had a good soaking rain and the next morming I glanced at that (unplanted) bed. It looked like it had ice on it. The complete surface was white. I had to laugh but was glad to see how well it worked. I tilled it under and it is now planted and growing. With relief, we are getting fairly regular rains so hopefully the drought has passed.
Incidently I had ordered directly from the factory and their website has excellent information and charts. Kristi