Hydroseeding is a method of planting that uses a pressurized spray to apply a slurry mixture onto the soil. This mixture typically contains grass seed, mulch, fertilizer, and a binding agent to hold the components in place. While the application is fast and efficient, the ultimate success of the new lawn relies almost entirely on the quality of the ground preparation before the slurry is applied. The process of preparing the soil creates the optimal environment for seed germination and root establishment.
Clearing the Site and Removing Debris
Before shaping or soil conditioning, the site must be cleared of existing materials that would interfere with seed-to-soil contact. This involves eliminating old turf, rocks, tree roots, and any construction debris present on the surface. A clean base allows the hydroseeding mixture to adhere properly.
Special attention must be paid to removing perennial weeds and unwanted existing vegetation. Killing these invasive plants at the root system prevents them from aggressively competing with the new grass for water and nutrients. If chemical weed killers are used, they must be selected carefully and applied with sufficient lead time to ensure the active ingredients dissipate or break down. Residue from certain herbicides can harm or prevent the germination of the new grass seed, making the waiting period necessary.
Addressing Grading and Drainage
Once the site is cleared, the land’s contour must be established to manage water flow. Proper grading is necessary to direct rainwater away from structures, preventing water pooling that can damage foundations and wash away the newly applied seed slurry.
This process involves rough grading to address significant changes in elevation, fill in low spots, and establish the main slopes. After major earth-moving, the soil should be allowed to settle naturally, or be lightly compacted. Low areas that collect water must be eliminated, as standing moisture will suffocate the delicate seedlings and create bare patches. The goal is a smooth, uniform surface that minimizes the risk of erosion and provides a consistent depth for the seedbed.
Soil Testing and Amendment
The chemical composition and nutrient profile of the soil are factors influencing long-term lawn health, making a professional soil test highly advisable. This analysis provides a detailed report on the soil’s pH level, which influences nutrient availability, and the concentrations of macro-nutrients like nitrogen (N), phosphorus (P), and potassium (K). Hydroseeding mulch and the starter fertilizer within the slurry cannot correct poor soil structure or chemistry.
Soil acidity or alkalinity must be corrected before seeding to ensure the grass can absorb nutrients effectively; most turfgrasses prefer a slightly acidic to neutral pH range of 6.0 to 7.0. If the test indicates a low pH (acidic soil), agricultural lime is applied, while sulfur compounds are used to lower a high pH (alkaline soil). These amendments must be tilled or incorporated deep into the soil profile (ideally 4 to 6 inches) and require time to react with the soil, often necessitating application weeks in advance.
The soil test will also guide the application of other necessary amendments, such as organic matter like compost or peat moss, which improves water retention and aeration, particularly in heavy clay or very sandy soils. Any required bulk fertilizers, especially those high in phosphorus to encourage root growth, should be worked into the upper soil layer at this stage.
Final Surface Preparation
The final stage of preparation focuses on creating the ideal seedbed texture immediately before the hydroseeding contractor arrives. The surface should be lightly tilled or scarified to a depth of 1 to 2 inches, which breaks up any surface crust that may have formed. Using a rake or light equipment to achieve a slightly roughened texture allows the hydroseeding slurry to adhere effectively to the soil.
After roughing the surface, the area should be lightly rolled or walked over to ensure the soil is firm enough to prevent excessive settling, yet still loose enough for root penetration. The final grade should be smooth, with no deep ruts or ridges, as these imperfections can lead to uneven coverage or “shadowing” when the slurry is sprayed.