Years ago, when we could get them at an easy price, we did that, and I think it did some good. Be sure, though, that you have them completely hydrated BEFORE adding to the planting -- or they may hydrate later, and actually push plants out of the ground.

I use about a tablespoon in each planting hole, mixed thoroughly with the soil, not just in the bottom of the hole. A tablespoon may seem laughable but it is enough to absorb a quart of water. If you use too much it will ooze out of the soil which does not enhance garden ambience. Although I used to mix it with water first, as I got used to the amounts to use I put it in dry because that is so much easier.

A few years ago on the Tropical Fruit Forum someone (Ethan maybe?) said that these crystals have some sort of growth promoter and that is why he used them. IIRC

Cath

I used water crystals in my sandy soil raised beds, and the brand that I used worked fine. Apparently some of the early brands were better that others as they contained a more "plant friendly" counter ion than the other type.

Since I had about 1000 roses I switched to unscented kitty litter - the cheapest - no frills. That is essentially clay.