What Mulch Is Used for Hydroseeding? | Choosing the Correct Mulch for Your Project

Mulch and water make up the bulk of a hydroseed mix with certain types of mulch being better for different hydroseeding scenarios. Consequently, the type of mulch you use can have a considerable impact on the success or failure of a project.

There are many varieties of mulch that can be used when hydroseeding each has its own set of uses in the field. Your choice will come down to a series of criteria and these criteria will largely be job dependent, although the price will also have a bearing on your choice.

We will look at the various types of mulch that are commonly used and discuss their use cases as well as their pros and cons as well as the impact the choices can make.

What Role Does Mulch Have in Hydroseeding?

Outside of the kind of seed that is going to be used, the biggest difference between hydroseed mixes is the type of mulch that is employed.

The role of mulch in hydroseeding is significant. Mulch is critical to making the hydroseeding process possible! It has various roles but it allows the seed to take on water before it is sown and acts as a shield and method of keeping the seed in place. It also makes the application easier as wet mulch is heavier than a mixture of seed and water, and therefore more straightforward to spray.

The mulch also supports the grass seeds in a variety of ways throughout their growth and development. In addition to aiding in the reduction of moisture loss from the soil and the maintenance of a uniform soil temperature, mulching also helps to decrease weed development while also adding organic material.

As the seed mixture rests on the soil after application, a blanket forms over the top of it. Its primary function is to hold the seed in situ while also shielding it from severe weather conditions and assisting in the initiation of seed germination.

Furthermore, because of the protections offered by the mulch blanket, the mulch can help contain and prevent the likelihood of soil erosion.

The Main Criteria in Choosing the Right Mulch for A Hydroseeding Job

When choosing a mulch for a project there are several factors that need to be considered to ensure the best mulch is chosen. It is true that many contractors have their personal favorite mulches but having a ‘one size fits all policy’ can lead to project failures.

The following are some general guidelines that may help you in making this decision:

1. Type of soil – Is it clay or sandy? If so, what type of sand?
2. Amount of moisture in the soil (moisture content) – How much do you want to add to the soil?
3. Soil temperature – Will you be working during cold weather months?
4. Amount of rainfall – Do you need to protect against runoff from heavy rain events?
5. What kind of grass will you be planting?
6. Cost

What Types of Mulches Are Used in Hydroseeding?

Various types of mulch are used in the hydroseeding process. These range from wood-based mulches, paper, and cellulose-based mulches to combinations of both. You will also find straw and cotton-based mulches together with specific erosion-prevention mulches, as well as other materials. 

Each of these types of mulches has its advantages, particularly in given situations, and are often used accordingly. 

Wood fiber mulch is somewhat more expensive than other types of mulch, but it does a better job of preventing erosion and promoting plant growth than the latter types of mulch. Wood mulch is especially beneficial for sloping lawns, and it is often used in the production of high-quality lawns.

Wood fiber mulches are produced from both soft and hardwoods and can also include a quantity of consumer wood waste. The best wood mulches are heat-treated in a pressurized chamber. This process produces longer wood fibers with a higher water-holding capacity. This can be around ten times the fiber’s weight.

Because of the long fibers wood fiber mulch can be used to help reduce soil erosion and can be utilized on slopes. Indeed, wood fiber forms the basis of erosion-specific mulches such as may be utilized on steep slopes a Bonded Fibre Matrix.

Wood fibers are an organic material with a carbon-to-nitrogen (C:N) ratio of 100:1. This ensures that they will decompose over time and enrich the soil. This process is enhanced with moisture and fertilizer in most hydroseed mixes.

Key Benefits of Wood Fiber Mulches

• Wood-fiber mulch is flexible in terms of use case.
• More effective in hotter more arid conditions than paper cellulose mulches
• Wood-based mulches offer stronger moisture retention capacities than straw or cellulose-based products, and with wood’s moisture reabsorption properties are superior.

Possible drawbacks of Wood Fiber Mulches

• Cost can be a drawback as wood fiber mulches are some of the most expensive mulches
• Wood fiber mulch needs to be applied at higher rates than paper cellulose
• Wood mulches can be more difficult to apply with any consistency with certain hydroseeder machines.
• Because of its high carbon content nitrogen is drawn from the soil as it decomposes , thereby lowering grass nutrition over time. A slow-release nitrogen source might need to be added to mitigate against this.

Paper Cellulose Mulches

Paper mulch is a low-cost mulch amendment that is especially well suited for instances where cost management is a priority and quality is a secondary factor. This strategy is useful for flat large fields bordering industrial zones or highway central reservations. It is also commonly employed in residential yards.

There is some debate about the merits or lack of regarding paper cellulose mulch. Its key benefit is its price with it being about the cheapest option. Just because it is cheap though, doesn’t mean it in ineffective. Indeed, if applied correctly where conditions suit its application, it can be an excellent mulch to use.

It is also flexible enough to be able to be used on slopes and can help with erosion control, although it is by no means the best solution if that is an issue. Perhaps its biggest drawback is that it has poorer water retention capabilities than other mulches meaning that it is not necessarily suitable for hotter climates. It also will require more water over time than other mulches, particularly in terms of after care while the seeds germinate and establish themselves.

Key Benefits of Paper Cellulose Mulches

• Considerably less expensive than wood fiber or wood/paper blended mulch. It is also generally cheaper than straw and cotton mulches.
• Paper cellulose mulches are usually easier to apply and don’t clog hydroseeders as much as other types of mulches can.
• Application rate of paper cellulose mulch is much less than wood mulch. 

Possible drawbacks of Paper Cellulose Mulches

• The mulch is of lesser quality and is less effective at preventing seeds from being washed away in poor weather.
• Paper mulches can crust over if applied too thickly preventing the grass from growing through.
• It is more suited to cooler climates as it has poorer water retention properties compared to wood, cotton, and straw.

Wood/Paper Blended Mulches

A wood/paper combination that is 70/30 wood and paper offers better erosion control and supports better grass growth than paper mulch alone but at a considerably lower cost than utilizing 100% wood fiber mulch.

This mulch is a very popular solution because it has the majority of the benefits of wood fiber mulch but at a reduced cost. If you need a better water retention than paper cellulose but don’t have the budget for wood fiber then this is a happy medium.

Although it will perform well it won’t quite have the capabilities of pure wood mulch and if you are in a dry and arid area you may not achieve much of a saving as you will probably find you will need to lay down a thicker mulch than if using pure wood fiber.

Another issue can be the carbon levels in the wood paper blend. These are higher than just pure wood fiber and you might need to add a slow-release nitrogen fertilizer to combat this of nutrients cold leach from the soil.

Key Benefits of Wood/Paper Blended Mulches

• Have most of the benefits of wood fiber mulches but a a reduced cost
• Readily available in most areas

Possible Drawbacks of Wood/Paper Blended Mulches

• Still more expensive than other types of mulch
• wood/paper blended mulches have even higher carbon content meaning nitrogen is drawn from the soil as the mulch decomposes 

Straw Mulch

In comparison to other mulches such as wood, paper, or mixed mulch, straw mulch consumes less water, is easier to place in the hydroseeding tank, and produces a more uniform layer of coverage when applied to the soil.

Straw mulch is heat treated and its use as a mulch in hydroseeding has become a more popular choice, its popularity growing especially strongly over the last fifteen years or so. 

Straw has long fibers and can be used in bonded fiber matrix mulches. It has a considerably better carbon-to-nitrogen (C:N )ratio of 35:1 than wood, paper, wood/paper blend or cotton mulches. This means that it is much kinder to the soil in terms of the amount of nitrogen it draws out when decomposing. 

Water retention is a key attribute for straw mulch as it can retain approximately five times its fibers weight in water. This water is also better utilized as straw has the ability to dispense the retained moisture more easily than other mulches, enabling the water to be used more efficiently.

Key benefits of Straw Mulch

• Straw mulch uses far less water than other mulches and the water that it does use is better utilized.
• It is not as expensive as wood fiber mulch and only slightly more expensive than paper cellulose mulch
• Straw mulch has a lower carbon-to-nitrogen ratio than other mulches.
• Better coverage from fewer tank loads can be achieved with hydrostraw mulch.

Possible drawbacks of Straw Mulch

• Straw mulch can be more easily blown or washed away in poor weather conditions.

Cotton Fiber Mulch

In research that was conducted by Auburn University’s Department of Agronomy[1,] cotton fiber mulch was shown to be a highly effective mulch. The study showed that cotton fiber mulch establishes seeds faster and stimulates grass growth better than either wood, paper-based mulches, or erosion control blankets.

Cotton, being a naturally permeable, absorbent, and biodegradable material, therefore makes it an excellent mulch for decreasing erosion and developing seedlings and is a cost-effective option for hydroseeding mixes.

Cotton Fiber Matrix

There are several cotton fiber options on the market with Cotton Fiber Matrix (CFM) being commonly used. Using cotton, straw, and a balance of performance-enhancing tackifiers and additives, it forms a seal over the soil similar to the role of a cotton bandage on a cut.

The CFM mulch is absorbent enough to retain moisture thus providing excellent seed-to-soil contact, while also being sturdy enough to protect the seed and soil from wind and heavy rain.

In addition, the cross-hatching of the fibers in the matrix allows air to circulate and is porous enough for the germinating grass to grow through without being obstructed.

As an alternative to wood and paper mulch, cotton fiber is an environmentally friendly organic substance. Its ability to control erosion and deal with grass on slopes up to  2:1 in steepness, as well as its use on used on level ground, makes it an attractive option.^[2]

Key Benefits of Cotton Fiber Matrix

• It may improve grass growth.
• it is a natural substance.
• Cotton fibers are very strong and long-lasting.
• Reasonably cost-effective.

 Possible drawbacks of Cotton Fiber Matrix

• Very little farmed cotton is grown naturally and it is subjected to numerous chemicals and pesticides.
• It has been known to clog up hydroseeder machines if the full tank load is not sprayed in one go.

Erosion Prevention Mulches

Erosion prevention mulches are, specifically prepared mulches that aid in the prevention of soil erosion. These are often utilized in locations that are highly prone to erosion, which include areas like slopes or water-adjacent regions and arid climate conditions to prevent soil attrition.

These mulches frequently contain binders and synthetic polymers, which are used to stabilize the soil or have been specifically designed to combat erosion.

Bonded Fiber Matrix

Bonded Fiber Matrix (BFM) is a product that has been developed to help with soil erosion issues. If you are planting seeds on a slope, paper cellulose mulch is often chosen as it helps keep the seeds in place. A bounded fiber matrix, on the other hand, is designed to hold the soil into place and is particularly efficient in terms of erosion control, holding the soil together while the grass’s root system can do so on a more permanent basis..

The mulch is typically made out of shredded wood that has been woven together and bonded with a tackifier to form long fibrous threads. These threads intertwine with one another, producing a locking pattern that attaches to the soil and keeps it in place.

The tackifier acts as a glue to keep the mulch in position on the soil. Despite the tight woven nature of bonded fiber matrix mulch it still allows the necessary moisture to get through to the seeds allowing them to germinate and eventually grow through the mulch.

Key Benefits of Bonded Fibre Matrix

• It provides protection against surface degradation caused by raindrop contact in the short term (after a twenty-four to forty-eight-hour curing period)
• Because it molds itself to the soil’s surface, it can prevent erosion from surface drilling.
• The long-term management of erosion is given by the grass germinating from the seed.

Possible Limitations of Bonded Fibre Matrix

• Because steeper slopes demand higher application rates, it is possible that the germination of seeds and the establishment of long-term vegetation would be impaired.
• Surface treatment alone is unlikely to enhance compacted, nutrient-depleted, or poorly draining soils to the extent that is required to maintain a healthy long-term vegetative canopy.
• BFM is an inefficient method for treating areas of less than half an acre. Where small scale application is needed it would be better to use alternative erosion control mulches.

Flexible Growth Medium

Mulch technology to combat soil erosion is continuing to evolve. In recent years we have seen the arrival of flexible growth medium (FGM). FGM combines interlinked hydrocolloids (super absorbent material often found in wound dressings) with wood fibers. When it is applied to the target area it creates a flexible absorptive blanket that attaches itself to the soil. Because of this FGM can be applied across uneven terrain and difficult seedbeds using paddle agitated hydroseeding equipment.

To secure soil on the targeted ground, FMG employs both mechanical and chemical bonding approaches. The contained wood fibers are thermally treated and combined with crimped man-made fibers, and performance-enhancing chemicals combine to produce an interlocking matrix that generates air space and water-absorbing holes that promote germination, lessen the effect of raindrop energy, and reduce soil loss.

When using FGM, the matrix created on the application has greater resistance levels to run off from heavy rains and severe rains. Tackifiers and flocculants, that are resistant to water, chemically attach the blanket formed by the matrix to the ground, absorbing water and allowing for enhanced plant development. When the matrix has dried and hardened completely, it is at its most effective.

FGM can be used for dormant seeding programs, long-term protection in dry areas, and other tasks that need extended protection.

Key Benefits of Flexible Growth Medium

• Use of hydrocolloids to enhance soil protection
• More effective than BFM and erosion blankets

Disadvantages of Flexible Growth Medium

• Expensive compared to other solution
• Requires larger hydroseeder/hydromulcher to distribute

Buying Mulches for Hydroseeding

The mulches used can be bought commercially and generally come in compacted 50-lb bales. These bales will often include a dye to aid with application uniformity when the mulch is sprayed.

A specific manufacturing technique is used to create certain mulches, which enables them to be discharged directly into the hydroseeding tank.

Certain mulches are manufactured to include synthetic fibers and or tackifiers. These are added to improve the abrasion resistance of the mulch. 

Final Thoughts: What Mulch Is Used for Hydroseeding

It is obvious the importance of selecting the most appropriate one for your requirements is critical.It is important to judge the climate and site conditions for each job when deciding on the mulch. 

It is true that on some jobs, particularly commercial jobs, the mulch is like to be specified as a wood fiber but otherwise, the eventual choice of mulch will often come down to personal preference and what works for you in terms of successful projects.

When you have flexibility in choice, particularly if you work in more temperate conditions, you can experiment more easily. you might well find that paper cellulose mulches do as good a job as wood fiber or blended mulches. In ideal circumstances, for example, a residential lawn that has a sprinkler system installed or is watered on a regular basis is likely to see very little performance difference in using paper over wood.

Site condition though, should be your lead when deciding on a mulch. In hotter conditions, wood or a wood paper mix may have clear benefits as is also the case with erosion management on a steep bank for example.

The wrong mulch choice can cause a project to fail. Sometimes saving a few pennies is not worth the risk if it puts the success of the hydroseed application in danger.

Notes:

[1] [1] Richard Guthrie, Director Auburn University: Cotton Research Report 

[2} Agriculture Journal, Vinay Bhaskar & Michael F. Walter: Living Mulch Performance in a Tropical Cotton System and Impact on Yield and Weed Control