One pound bag.
Synthetic polymer has been found to improve tree and shrub seedling survival, especially where trees cannot be irrigated. Sold in dry granular form, the polymer absorbs up to 400 times its weight when added to water. The water stored in the hydrated crystals is available to the plant roots, providing an extra reserve to help the plant through periods without rainfall or irrigation.
A large handful of hydrated polymer should be mixed with the soil backfill in each planting hole. One pound of polymer will be sufficient for 80 to 100 trees. Polymer may also be used for flower and vegetable transplants. In containers, it helps cool plant roots during hot summer months.