This is a viewer bought jelly crystals in a store, those that expand to a hundred times their original size in water. They wonder whether they can actually put it in their garden soil to retain moisture or will it do any damage to the plants?
It won't be damaging and interestingly enough we've done a lot of work in horticultural and turf situations on these products. They expand a hundred times their size in distilled water, but when you use water with a little higher pH, as you do with water in soil, the expansion is probably only 10-20 times. The gels themselves will release moisture to dry soils, if they come in contact with the root, some of our results shows they have a greater affinity to roots. We've never seen a real positive effect from a watering standpoint.
Data shows there is a thermal buffering effect. It doesn't get too hot because of the moisture in the gel. We're not big fans of those except in container plants where they've proven to be a good thing to buffer the temperature. It's the exact same gel that's in baby diapers.