The hydroseeding process involves mixing grass seeds with natural wood fibers, fertilizer, binding agents and water to create a slurry, and then that slurry is sprayed onto the ground under pressure through a hose. As the slurry dries, the binding agents and wood fibers adhere to the underlying soil and hold the seeds in place, and the fibers and fertilizer act as a growing medium that encourages germination of the seeds and development of seedlings.
Hydroseeding may be an effective option for establishing turf in large areas and on steep slopes where traditional seeding methods are difficult. The technique, though, has some advantages and disadvantages.
Speed of Establishment
In ideal conditions, hydroseeded grass seeds often germinate within one week, and turf can be well-established within three to four weeks, which may be faster than turf seeded with a traditional broadcast method. Sod, of course, offers instant establishment as soon as it's installed, but the hydroseeding process is faster than the process of installing sod.
The binding agents and fibers in the hydroseed mixture not only hold the grass seeds in place; they also can help to hold soil in place by lessening the erosive effects of rain and runoff water by forming a barrier between the water and the soil.
For effective binding and establishment of a mulch barrier, the hydroseed slurry must dry for 24 hours before it's exposed to rain or irrigation.
The fiber contained in the hydroseed mixture acts as a mulch and helps to maintain a consistent level of moisture around the seeds, encouraging germination and protecting the seedlings from drought stress. The fiber absorbs water and holds onto it, which makes water available to the seedlings for a longer period of time than it is in sodding and other seeding methods. The dried slurry also forms a barrier above the soil that helps to hold moisture in the soil longer.
Even with these advantages, however, hydroseeded grass may need additional irrigation during prolonged dry periods. The fiber in the hydroseed mixture degrades quickly. So the benefits it provides last for only part of the growing season.
Hydroseeding is substantially less expensive than the installation of sod, which may cost as much as four times more than hydroseeding to cover a comparable area. The process must be done by a qualified contractor, however, and the cost of labor and specialized equipment generally makes hydroseeding more expensive than traditional broadcast seeding.