They hold moisture in the soil of hanging baskets and containers, so plants do not dry out as quickly, improving displays and growth even in dry conditions. You may only need to water every 7-10 days.
Adds Potassium - Not Sodium
Another advantage of Rain-Gel and Rain-Mats is that they slowly release small traces of potassium, unlike other products that release sodium (salt) which can adversely affect some plants.
"Rain-Gel" water retaining granules give much better performance than products that are sodium based. "Rain-Gel" and "Rain-Mat" products are potassium based and take up water in a few seconds, forming a fine textured jelly. This rapid uptake ensures much better performance within the soil and provides an immediate reservoir to plant roots. Quite simply, the "Rain-Gel" granules "grab" the water immediately, before it can drain through the potting mix (unlike other slow acting granules). Saturation can be achieved with one watering, instead of having to rewater several times. The roots are then able to draw water from the reservoir as and when needed.
One teaspoon of Rain-Gel mixed into the potting soil at root level is enough for a 12" hanging basket. Use two teaspoons for larger baskets.