Hydroseeding is effective, especially for steep slopes, rocky terrain and other areas where conditions make it impractical for other methods of seed application. Hydroseeding is the application of a slurry of seed and water to soil. The slurry may also contain mulch (hydromulching), a tackifier and fertilizer. Mulches are made of wood fiber, paper or excelsior, and their purpose is to hold seeds in place, help retain moisture and provide protection from erosion; mulches are usually dyed green as a visual aid in even distribution. Rates of application for most mulches are between 1500 and 2300 pounds per acre. In general, hydroseeding/hydromulching is most successful in moist climates or in irrigated areas.
When hydroseeding, most authorities agree that germination is better when seed is applied first with 5-10% of the mulching fiber–the balance of the mulch being applied separately as a second step. This approach ensures optimal seed/soil contact; otherwise, many seeds are wasted because they become suspended in the fiber. In addition, it is important that proper procedures are followed to minimize the amount of time that seed is circulated through pumps or paddles prior to application. Over-circulation may damage the seed.