water gel crystals

REMEMBER: All application rates will vary depending on type of soil, type of plants as well as the region that you live in.
*Clay Soils require less WaterSmart Crystals
*Sandy soils require more.
*Dry/arid regions require less WaterSmart Crystals.
*Wet/cool regions require less.

* When applying your WaterSmart Crystals dry, do not use more than necessary - more isn't always better.
* WaterSmart Crystals need to be worked into the soil to provide equal distribution.
* WaterSmart Crystals left above ground will breakdown faster due to sunlight. Ensure crystals are buried for good long term use.

For 1 gal root size container- use 1/4 cup, 3 gal - use 1/2 cup, 5 gal - use 3/4 cup, 15 gal - use 1 1/2 cup. Dig a hole at least three times the size of the container and dig in your crystals, thoroughly mixing them with the soil that will surround the plant. After planting, dig a small divot around the tree to collect water. If the tree is on a slope leave an area on the top side open as a reservoir for the water to seep into the ground to be absorbed by the crystals. (1/4 cup = 2 oz. crystals)

VEGETABLES and FLOWER BEDS
Use 1-3 pounds of crystals per 100 square feet at 4-6" depth cultivation. Use less in areas of plants that like drier conditions and more in areas of moisture loving plants. After planting, a good coat of mulch will dress up the bed and cover any loose crystals. This gives the bed a finished look, protects the crystals from the sunlight as well as cuts down on weeds.

I hope this is of some help

The answer to your question is yes, water storing gels such as Broadleaf P4 are completely safe to use with edible plants. They are completely non-toxic and break down into non-toxic substances either when exposed to aluminium, UV light or after time (in the case of P4 approx 5 years).
The only thing taken up by the plant is the water stored by the gel, unless you soak the crystals in a fertilizer solution prior to mixing with the compost. In that case, both the nutrients and the water will be absorbed by the roots.
It's also well worth doing as the factor which normally limits productivity and maturity of plants is water availability- on all the trials with Broadleaf P4 the plants grew larger and stronger sooner and also matured faster, as they had access to the water whenever they required it via the granules- which meant that the first crops were ready well in advance of untreated plants.