Mid August to mid September is generally the best time of the year to plant new grass seed. Hydroseeding is a very popular way of planting grass over large tracts such as golf courses or along roads. Hydroseeding is much more cost effective than laying down sod, and is generally faster and better than sowing dry seed.
In the hydroseeding process, the landscaper prepares a mixture of seed, water, fertilizer, fiber mulch, and several additives and then sprays the mixture onto the desired area with a hose. One of the additives present in most hydroseeding mixtures is a crosslinker. Amspec sells one such crosslinker that some companies use in some hydroseeding applications, potassium pyroantimonate. The purpose of the crosslinker is to facilitate bonding of the grass slurry to the soil. The result is a kind of mat over the soil that allows enough rainwater to filter through without eroding the soil or washing away the seed. Hydroseeding slurries with a crosslinking agent are especially useful on steep slopes.