Hydroseeding uses a mixture of water, seed, mulch, fertilizer, and tackifier (if needed for a sloping area) and is sprayed out over your lawn. The mulch that some companies, including ourselves, include in this mixture serves a couple of purposes. It creates a high moisture bed which produces the best conditions for the germination of the seed and also serves as a safeguard from runoff and birds so your finished product is an even carpet of lawn can develop and flourish.