What is Hydroseeding?

Mike Donley

Mike Donley holds a Bachelor of Science degree in business marketing and an MBA in International Marketing. He has 30+ years of experience in sales, publishing, writing, editing, public relations, and industrial marketing. He has been with Finn Corporation since 2019.

Origin of Hydroseeding 

The concept of Hydroseeding or hydromulching as it is also known, is credited to Maurice Mandell of the Connecticut Highway Department in the 1940’s.1 Mandell’s simple concept was to mix seed and water and spray that on the areas around Connecticut highways and roads to sow grass after construction to prevent erosion of the soil. From that start, Hydro-seeding developed into a highly technical process that we will discuss in the balance of this article. Charles Finn, founder of Finn Corporation, the largest hydroseeder manufacturer in the world, invented the first hydroseeder in 1953. 

What is Hydroseeding? 

Hydroseeding is a method of planting seeds by spraying a water-based slurry of seed, mulch, fertilizer, and other soil additives over prepared soil. Hydroseeding is the most efficient method of planning for all but the smallest of seeding applications. The keys to hydroseeding’s high efficiency are combining all the essentials for fast, healthy seed germination in one highly efficient application. The critical elements are: 

  • Good seed to soil contact 
  • Fertilizer
  • Moisture retention
  • Seed Protection

 Effective hydroseeding works by first testing the soil to determine what additives, if any, are needed to condition the soil for optimum seed germination and growth. The soil must be “prepared” for planting which includes loosening highly compacted soil to allow the plant roots to grow deep. Then, based on your soil test results, select the right blend of native seeds to create the plants you want to establish. (Note that I say “plants” because more than grass may be planted via hydroseeding). Select the correct fertilizer, tackifiers (when seeding steep slopes), additives (elemental sulfer, aluminum sulfate, iron sulfate, nitrogen, lime or other soil conditioners), and mulch to give your planting the best opportunity for a fast start and healthy, sustained growth. 

Hydroseeding for Erosion Control

As you can see, there is much more to hydroseeding than slopping some seed and mulch on the ground and hoping it will grow! It has developed into a sophisticated process that is critical to the environment after construction, especially large projects such as roads, bridges, and mining operations. It is a main technique for preserving river banks to keep runoff from getting into our waterways. It is also used extensively for mine reclamation to return these large sites back to their natural state when the mine is closed.

In fact, just about any place you see large amounts of ground disturbed for the purposes of building or transportation you will find hydroseeders on the scene when the work is done to restore the ground and keep the soil from eroding away due to wind and rain. It is even common in creating recreational areas like parks and golf courses. It’s cost effective and fast, and that makes it the go-to method in many applications.

Pros and Cons of Hydroseeding

Since I’ve been touting the benefits of Hydroseeding, I don’t want to leave the impression that it is the perfect solution in every case. There are times when alternate methods of establishing grasses are better than Hydroseeding. 

Small Area Hydroseeding

When planting a small area it may not make sense to use a hydroseeder. By the time you do the setup work required for a hydroseeder you may be able to finish a small lawn by spreading seed by hand with the help of a mechanical spreader. Then you may spread some straw over it to protect it from birds and help it retain moisture and call it a day. While this method adds some labor to the lawn installation, it also saves cost by investing in a bit of sweat equity.

I Want a Lawn Now!

When you have more money than patience you may prefer to install sod rather than hydroseed a new lawn. With sod there is no waiting for seed to germinate, you get your lawn instantly. There is lot to be said for going from dirt to grass instantly! The drawbacks with sod are the expense, limitations on the grass variety, and establishing a deep, healthy root system quickly. It’s not uncommon for sod to cost more than X times what Hydroseeding costs. With Hydroseeding, you can choose the exact species and blends of grass that you want for your lawn, and by planting seeds directly in the soil, rather than established grass, the root system of the grass grows deep, strong and healthy as long as you have prepared the soil properly, fertilized and keep it watered.

When to Hydroseed

Naturally, when to hydroseed depends on your climate. The ideal time is when it is cool but not cold, and you are expecting a reasonable amount of rainfall. The rain will help defray the costs of watering. Fall is widely accepted as the best time of year to install a lawn. Installing a lawn in early fall gives the lawn time to establish before winter sets in. The lawn will go dormant in the winter and then have the rain and cooler temperatures of spring to give it a good start before a hot summer.

Planting in the early spring is also acceptable. Taking advantage of spring rains and cooler temperatures makes for very good growing conditions. The disadvantage is that if spring is followed by a hot summer, it may take more watering for the first year to keep it alive and thriving in the summer. Finally, unless you have an abundant and cheap source of water its best not to plant in the summer. There is not much point in fighting off high temperatures if it is possible to avoid it.

Hydroseeding Equipment

Hydroseeders come in all shapes and sizes. While I am not going into great detail about products, features and benefits of different brands, I do want to offer an overview of the key differences.

Jet or Mechanical Agitation

Here is where you can start some fights. Maybe not to the Ford vs. Chevy level but commercial Hydroseeding professionals definitely have their preferences. In general, you will find jet agitated equipment used more commonly for residential and light commercial applications, and mechanical agitation for both the small and larger jobs. 

Easy Lawn Jet Agitation System – 200 Gal.

The advantages of jet agitation are that it is less expensive and generally works well with smaller tanks and applications. This makes it ideal for residential and light commercial work. For example, if you are a landscaper hired to plant the “islands” in a retail parking lot. Jet agitation equipment would be ideal for this. 

If you are hired to plant the seven acres around a new hospital complex, you would want larger and beefier equipment that can plant a half acre or more on each load and mix your slurry very fast. Mechanical agitation typically mixes faster and more thoroughly for larger equipment and can process heavier mulch products. Jet application machines do well with lighter mulches that are paper based. However, some jet agitation equipment can handle the heavier mulches as well.

The bottom line is that it is your application and budget that determines what type of equipment is best for you. Consider the type of work you are going after, and then research the equipment designed for that application and you will do fine.

FINN Mechanical Agitation System 900 Gal.

Available Sizes and Types

Hydroseeders come in sizes ranging from 100 to 5,000 gallons. Hydromulch may even be applied by helicopters or planes depending on the available access points to the jobsite. Hydroseeders are available on skids for installing on a truck bed, chassis or even a tractor, as well as trailer versions designed to be towed by trucks and tractors. 

Pump Technology

Hydroseeders have different pump technologies available with the most common being centrifugal and vortex. Agitators and pumps may be driven by mechanical or hydraulic means. Hydraulic systems don’t require a clutch or belt which reduces potential mechanical failure points but they do require additional hoses and valves that offer their own challenges. 

Spray Methods

Spraying is achieved through a boom or hose system. The largest equipment can spray nearly 370 feet through its boom, allowing access to areas difficult to reach by truck or hose. Hose comes in many sizes and lengths allowing for precise application and distances up to 300’ or more from the truck.

Dual Boom Spraying 

Costs of Hydroseeding

The costs of sod, seed and Hydroseeding are regional so I can’t really give you accurate pricing for your area. However, in general terms, planting seed alone will be the cheapest method because it eliminates the Hydroseeding equipment and extensive labor of sod. 

Hydroseeding comes in second and will be about twice the cost of seeding alone. Sod will run about 2-3 times the cost of Hydroseeding making it the most expensive option of the three. Keep in mind that these are very general and depending on your area the costs could vary wildly. It’s best to inquire if you are considering a lawn installation project.

Do it Yourself, or Hire a Pro?

I mentioned above that there are many considerations with Hydroseeding and doing the job right. While this is true, it’s not rocket science and if you are handy and want to invest the time, you can do a small job like a typical yard yourself. Many FINN dealers rent equipment and many rental stores carry hydroseeders. For a few hundred dollars a day you can get a 300 or 600 gallon hydroseeder and do the job yourself. 

If doing the job yourself, take the time to learn how to do it right. This article is not intended to be a detailed “How To” manual for installation, but I will summarize the steps to give you an idea of what is involved so you can make an assessment of whether you want to take this on or hire it out.

  1. Test your soil. Get soil samples from your yard so you can test your soil Ph levels. The experts at Pennington Seed state that, “Soil pH preferences vary between regional lawn grasses, but most grasses prefer soil pH between 5.8 and 7.2. Warm-season grasses tolerate slightly lower pH, while cool-season grasses prefer pH slightly higher.”2 Just Google “test my soil” and you will find some resources that explain how to do this and where to send your soil samples. Figure a couple of weeks for this and a $25-$50 fee.
  2. Measure your lawn so you know how much seed and additives you need to establish the lawn.
  3. Prepare your soil by making it is smooth and de-compacted to at least 3”
  4. Purchase Your Consumable Supplies (No skimping here, use the recommend quantities) A. Find a local source with experience with Hydroseeding and they can help advise you on what materials and how much is needed based on the size of your yard. B. Select the seed type you want for your lawn. You will have some choices for the type of seed blend that grows well in your area. C. Select the fertilizer that blends well in the hydroseeder and is designed for new lawns. D. Select the additives need to get the soil Ph to the right levels based on your soil test.
  5. Rent the hydroseeder. Most commercial grade hydroseeders use mechanical agitation to mix your slurry. This is widely accepted as the best method to mix. Your rental agency may offer equipment with “jet agitation”. This will work for smaller tanks but mechanical agitation tends to mix the slurry more thoroughly.
  6. Get the equipment and consumables back to your job site and mix it up. Follow the instructions with the equipment and you will be fine. Just don’t skimp on quantities of components. Make sure you mix it thoroughly and that you have the right consistency. Not to thin or thick. Ask the supplier about the consistency of the slurry for the products you have selected.
  7. Don’t skimp! Whether spraying from a hose or a boom, be sure to cover the ground thoroughly. Thorough covering is essential to establishing a healthy lawn. You’ve spent some money on this job and don’t cut a corner at the last minute and try to save a couple of bucks. This may cause the entire application to fail. Do it thoroughly and do it right.
  8. Once finished, clean the equipment and return it to the rental agency. You may also be able to return any unopened bags of consumables.
  9. Keep the lawn watered according to the label instructions on the consumables and watch your new lawn grow! You will probably be cutting grass in 3-6 weeks depending on the seed selection and growing conditions.

Seed Selection

The purpose, of course, is to grow grass so select a seed blend that both grows well in your area and has the texture and color you want for your lawn. I say blend because often a blend of perennial and annual seed is best because the annual grass comes up quickly to protect the perennial seed while it germinates. Grass seed manufacturers produce seed designed specifically for your area. There is seed for shade or sun; sand or clay, dry or wet and probably many more. Choose what is right for your lawn and don’t skimp in the application. Always apply it at the recommend level. You will find a label on the seed with instructions so be sure to read that and know what you are getting and how much to install.

Some common grass choices are:

  • Bentgrass – Found on many golf courses in the Northern U.S.
  • Bermuda – Found on many golf courses in the Southern U.S.
  • Cetipede Grass – Likes the warm, humid areas of the south.
  • Fine Fescue – Tolerates shade well but not hot and dry areas.
  • Kentucky Bluegrass – Popular in the north, not good for deep shade
  • Ryegrass – Does well in the cool-season areas of the north
  • St. Augustine – Likes warm areas of Florida and the Gulf Coast
  • Tall Fescue Cool-Season but also can tolerate some heat
  • Zoysia – Middle US and east towards the Carolinas

I found some of this content on Scotts.com2 so be sure to do your research on what grass appeals to you and what grows well in your area before you plant.

Fertilizer

Choose your fertilizer based on your soil sample. Make sure it has the nutrients that your seed and soil require. Understand the three main components of fertilizer. Nitrogen, Potassium, and Potash. I learned this little phrase from a summer job that helps me remember what each does: “Up, down and all around.” Up, is for the green grass you see, nitrogen makes the grass green and healthy looking. Down, Potassium is for a healthy root system, and “All Around” is for the overall plant health such as disease resistance. Make sure these combinations are designed for a new lawn because the chemical makeup will be different for established lawns.

Tackifier

This is essentially a glue that holds the Hydromulch in place on steep slopes. There are many varieties to choose from. 

  • Polyacryalalmide (PAM) is a synthetic tackifier with a sand-like texture. It only takes about 3-5 lbs per acre and is fairly inexpensive. 
  • Polysaccharide (GUAR) has a flour-like consistency and is an organic material. It typically takes 20 to 60 pounds per acre depending on the slope and is more expensive than PAM. It will hold up better under rainy condiditons.
  • Other styles include: Fibers, Cross-linkers and Liquids.

Hydromulch

Hydromulch is the large bales of “Green Stuff” you see loaded into the hydroseeder. The main components are paper, wood, paper/wood blend, bonded fiber matrix (BFM), and flexible growth medium (FGM).

  • Paper – Typically made from recycled newspaper and is less expensive than the other mulches. It is very easy to spray for all hydroseeders including jet agitation machines. It must be kept wet or it will “paper mache’” and become difficult if for grass to pass through as it grows. It is vulnerable to erosion since it is light.
  • Wood – Better moisture retention and less vulnerable to erosion than paper and It creates a strong matrix when mixed with tackifier and sprayed at the proper rate. 
  • BFM/FGM – High performance products that are essentially spray on blankets that form a tight matrix. It is thicker when mixed so it takes very thorough mixing to achieve the right consistency. These are used by the major players in the Hydroseeding industry using the largest tanks and completing the biggest jobs.
Hydromulch Spray

Lime, Sulphur and Gel

Lime is used to raise the Ph of acidic soil. For a more basic or alkaline soil you can add Sulphur to lower the Ph. They come in powdered, pelletized or liquid forms and any form is suitable for a hydroseeder. Gels are used to help with moisture of retention. The tiny crystals in the Gel hold 100 times their weight in water and then slowly release it after a rain to keep the seed moist.

Topsoil Alternatives

Topsoil alternatives are used on soils and substrates that have been stripped of their nutrients from construction and other land-disturbing activities. It can be very expensive to bring topsoil in to large areas to give new grass seed a chance to thrive. These topsoil alternatives are sprayed with a hydroseeder and are a good substitute to allow seed to germinate and thrive. For a more detailed look, check out Profile Products “ProGanics Biotic Soil media (BSM) at this link.4 

Summary

We covered a lot of ground here (pun intended) with this overview of hydroseeding. We learned about the importance of hydroseeders in erosion control, what goes in the tank to make the seed grow, when the best time to plan is and so much more. I encourage you to take a look at the sources below if you want more information and feel free to comment on the post with more details. There is way more content than I can include so your comments can help other readers learn more about the subjects that interest them.

  1. https://en.wikipedia.org/wiki/Hydroseeding
  2. https://www.pennington.com/all-products/fertilizer/resources/does-your-lawn-need-lime#:~:text=Soil%20pH%20preferences%20vary%20between,grasses%20prefer%20pH%20slightly%20higher.
  3. https://www.scotts.com/en-us/library/grass-grass-seed/identify-your-grass
  4. https://www.profileevs.com/products/engineered-soil-media/proganics-biotic-soil-media-bsm

Material blowers are the most versatile machines

Material Blowers: The Most Versatile Machines in Your Fleet

June 11, 2021

Material blowers are versatile machines that can reduce material costs by up to 40% and increase productivity by up to 700%. They disperse a variety of material including mulch, soil, seed and even rocks.

Straw blowers can do more than just cover seed

Straw Blowers Can Do Much More Than Just Cover Seed

June 11, 2021

Straw blowers can be used for seed protection, raindrop erosion prevention, mud mitigation, animal bedding, soil stabilization and much more.

Why Ground Prep Attachments are Key to Sowing New Grass

April 15, 2021

Ground prep attachments clear terrain, loosen soil and level the field in advance of applying a hydroseeding slurry or sod for a beautiful bed of grass.

Have a question about a blog post? Ask it here.