Hydroseeding 101

Hydroseeder on construction site

Hydroseeding is a method of hydraulically applying seed and mulch.

You can hydroseed lawns, slopes, residential developments, highway medians and almost anywhere else that needs vegetation and erosion control. The method and products vary per project but the outcome is the same; fast and widespread ground cover.  

In this article, we’re going to cover some hydraulic seeding basics including:

  • Hydroseeding vs. hydromulching
  • Why hydroseed?
  • What is a slurry?
  • Types of hydromulch
  • Application rates

We’ll tie everything together with a hydroseeding case study at the end.

Hydroseeding vs. Hydromulching

Even if you’re new to the erosion control and landscape industry, you have likely heard the terms “hydroseeding” and “hydromulching.” Other versions include hydraseeding, hydraulic mulching, hydraulic mulch seeding.

Hydroseeding school with hydromulch

Although these words are used interchangeably in our industry there is a technical difference between the two.

Hydroseeding applies a slurry for hydromulch, seed, fertilizer and amendments. This hydraulic seeding method intends to establish vegetation for ground cover and erosion control.

Hydromulching generally includes just mulch and tackifier. This method establishes a temporary protective cover over bare ground in order to lock in soil for erosion control.

Although there are slight differences in these two terms, most industry professionals use these terms interchangeably.

For consistency sake, our team usually sticks to the term hydroseeding.

Project plans, owners and site requirements will make the distinction clear by specifying what should be applied. If there is ever any doubt, however, just ask.

Why should you hydroseed?

There are many different reasons you might need to hydroseed. In almost all situations, however, the goal is fast and thorough coverage.

Landscapers for example, hydroseed subdivisions for a uniform application.

Contractors on the other hand, hydroseed to establish vegetation and control erosion on construction sites. Contractors also use hydromulch in lieu of rolled erosion control blankets.

Hydroseeders also give you access to hard to reach places. These machines have hoses that extend and spray beyond the truck.

Hydromulch steep slope on new construction site

Lastly, hydroseeding combines three actions in one: seeding, fertilizing and erosion control ground cover. This triple threat not only saves time but effectively establishes vegetation and controls erosion.

What is a slurry?

When you hydroseed you hydraulically apply a slurry; a mixture of water, mulch, seed, fertilizer and soil amendments.  

The slurry includes everything you need for proper vegetative establishment:

  • Seed
  • Nutrition through fertilizer, lime and amendments
  • Ground cover with hydromulch
  • Water

The slurry’s products and quantities will depend on the application rate. Mulch manufacturers specify application rates for hydromulch. It’s important to follow these rates in order to achieve effective erosion control and vegetation and avoid over (or under) spraying.

Types of Hydromulch

There are hundreds of hydromulches on the market today. There are single product bales, blends and high performance hydraulic mulch. Here are a few common mulches.

100% Cellulose

This hydromulch is made of fully biodegradable 100% recycled cellulose fibers. 100% Cellulose Hydromulch is also known as paper mulch. It is recommended for erosion control on slopes less than 4:1.

100% Cellulose is inexpensive compared to hydromulch blends and high performance mulches. For that reason, it is a popular choice for ground cover when slopes are not too steep and erosion is not severe. 

100% Wood Mulch

This hydraulic mulch is made from 100% wood fibers that are derived from wood chips. 100% Wood Hydromulch should be applied on slopes that are less than or equal to 2:1.

Apply 100% Wood Mulch when you need greater erosion control. It has greater moisture retention than 100% Cellulose which means it aids vegetative establishment.

70/30 Hydromulch

70/30 Hydromulch is a blend of wood and cellulose fibers. These bales are made up of 70% wood fibers and 30% cellulose fibers. For that reason, 70/30 Hydromulch should be applied on mild slopes that are less than or equal to 3:1 in grade.

High Performance Hydromulch

High Performance Hydromulches are engineered for improved moisture and soil retention. These mulches are often made from wood fibers but some mulches are made of straw.  

These mulches are specified for steep slopes, severe erosion and long term soil loss mitigation. 

High Performance Hydromulches can be more difficult to apply than the traditional products like paper mulch. It’s important to abide by the specified application rate when spraying High Performance Mulches. 

Application Rates

The application rate refers to how many pounds of hydromulch is applied per one acre. This rate varies by product so it is important to follow the manufacturer’s recommended application rate.

Site conditions, project goals and the type of hydroseeder you use also affect product selection and application rate. Hydroseeding bare soil for turf establishment, for example, will require a different rate than hydroseeding steep slopes for erosion control.

For best results, always adjust your products and rates to the needs of your specific site.

Two Step Solution: Hydroseeding Project

The contractor on a construction site in Chesapeake, Virginia was struggling to achieve vegetative establishment on a two-acre stock pile.

Bare slopes before applying hydromulch and soil ammendments

After several failed seeding attempts, we requested a soil test. The test determined that the soil had a low concentration of organic matter.

Organic matter provides the soil with nutrients, helps with moisture retention and contributes to key chemical processes.

We suggested applying ProGanics Biotic Soil Media to replenish the depleted soil. ProGanics is an affordable alternative to top soil. It has demonstrated success with improving sustained vegetation which is exactly what this site needed.

Spraying ProGanics top soil alternative

ProGanics’s application rate was determined by the soil’s content of organic matter, which fell between 0.75% and 1.5%.

4,500 pounds of ProGanics was applied per acre which totaled 9,000 pounds for the project.

A High Performance Hydraulic Mulch followed the ProGanics. We chose a mulch that has a lot of tackifier in the matrix which helped bond the slurry, soil and ProGanics.

4,000 pounds of hydromulch was applied per acre which totaled 8,000 pounds for the project.

The slurry also included Seed, Lime and Fertilizer at the following application rates:

  •             Seed: 150 lbs/acre for a total of 300 lbs
  •             Fertilizer: 200 lbs/acre for a total of 400 lbs
  •             NeutraLime: 80 lbs/acre for a total of 160 lbs
Vegetated slopes after hydroseeding

As you can see, with proper planning and application, grass began to grow and the stockpile has been properly vegetated.

Contact Colonial with all of your hydroseeding questions

Hydroseeding is an effective seeding and erosion control strategy for sites of all sizes. It is important to understand how different mulches, slurries and application rates will result in different outcomes. For more in depth product information or site-specific questions, contact our sales team. We can recommend products to solve your site’s problems as well as connect you to equipment suppliers and hydroseeders in the Mid-Atlantic region. 

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