Why You Need To Know What’s In Your Growing Media Mix

Lucas Greenhouses uses PBH Nature’s Amendment rice hulls in its growing mixes, as a sustainable and lower cost alternative to perlite.

With the number of growing media components and pre-mixes now available, it may be difficult to keep them all straight. But ultimately, your most basic objective is to incorporate growing media mixes that meet your operation’s needs and provide the most nutrition to the crops you grow.

It’s important to remember that the success of growing healthy plants still depends on the grower and the cultural management practices that are implemented, says Dr. Brian Jackson, Associate Professor of Ornamental Horticulture, North Carolina State University.

“No new product or amendment can make growing great plants fool-proof,” he says. “Skill, experience, and attention are still needed to manage crops during production. With this being said, the use of new materials or products can, in some cases, yield cost savings or lead to the reduction of inputs, depending on the location and type of operation.”

The Best Mix For Your Crops Should Be Based On Properties

When it comes to choosing the right components or the correct mix to compose the proper growing media for your crops, there are many considerations growers need to keep in mind, starting with the same basic principles that have been used for years, says Joe Moore, Head Grower at Lucas Greenhouses in Monroeville, NJ. These include what crops you’re growing, what size pot you’re growing it in, and how long of a crop it is, Moore says.

The biggest advancement in growing media for Lucas Greenhouses, says Head Grower Joe Moore, was the ability to invest in a high-quality in line mixing system.

“All of those things impact media particle size needed, aggregates to be added and their particle size and composition, soil amendments to be added (lime, humus/topsoil), and crop protection or fertilizer options to be added in the mix pre-plant,” he says.

According to Texas A&M University’s AgriLife Extension website, it’s best to focus on physical and chemical properties more than components; thus the most effective growing media should be one that is:
1. Porous and well-drained, yet retentive of sufficient moisture to meet the water requirements of plants between irrigation
2. Relatively low in soluble salts, but with an adequate exchange capacity to retain and supply the amendments necessary for plant growth
3. Standardized and uniform with each batch to permit the use of standardized fertilization and irrigation programs for each successive crop
4. Free from harmful soil pests, pathogenic organisms, soil insects, nematodes, and weed seeds
5. Biologically and chemically stable following pasteurization; primarily free from organic matter that releases ammonia when it is subjected to heat or chemical treatments.

Different Components Can Change The Need For Inputs

The right growing media mix for the right crop can save growers money on other inputs like crop protection and fertilizer inputs, Moore says.

“You can always impact crop protection costs directly by the choice of growing media,” he says. “If the mix drains poorly and has poor air porosity, you will by default be spending more money on fungicides to help control root rots, or you will be dumping product that is either inferior or dead.”

Finding the right balance of components and growing media additives can also impact growers’ input costs. For example, because mycorrhizal fungi help plants absorb more nutrients and water, growers can significantly cut back on chemical inputs, says Graham Hetland of Mycorrhizal Applications.

Incorporating hydrogel into growing media mixes can also have an impact over time, says John Wynne, Horticultural Business Development Manager for Evonik; however, this is something growers will have to determine through close monitoring of leachates, he says.

Water should be considered an input, even though it is a necessity for plant growth. Still, irrigation techniques can play a role in how precise media components are, says Soren Møller Nielsen, National Sales Manager for Pindstrup.

“Choice of growing media goes hand-in-hand with implementation of irrigation strategy,” he says. “With an optimized substrate and irrigation strategy, better plants can be grown with less input of water, fertilizer, labor, etc.”

HydraFiber from Profile Products is allowing growers to reduce irrigation, fertilizer, and chemical inputs in early trials.

Early feedback from grower trials on Profile Products’ HydraFiber has indicated potential savings for growers, as well, says Business Manager of Horticulture Jennifer Neujahr.

“Most growers are able to grow in mixes containing 20% to 40% HydraFiber without needing to make major changes in their growing practices (water, fertilizer, etc),” Neujahr says. “However, customer feedback has indicated that HydraFiber may allow them to reduce irrigation and chemical usage due to increased available water. Many early adopters have informed us that they are starting to fine-tune their growing practices with water, fertilizer, and plant growth regulators as they learn how to grow with HydraFiber.”

Jiffy is also working on a range of substrates that will hold more water and fertilizer than a traditional substrate, says Miguel Meneses, Substrates Product Manager, for Jiffy Products International.

“They allow unbelievable dry down levels without any damage to the crops, have outstanding capillarity, and can be rewetted easily,” he says. “They allow growers to produce compact, toned plants, and reduce leaching of water and nutrients.”

Savings Versus Quality

One of the biggest misconceptions growers have when it comes to selecting growing media mixes or components to blend for their own custom mixes is that price trumps quality. Instead, the opposite is true, Meneses says.

“When you buy a cheaper mix, you are saving a bit of money, just like when you fill less to each pot,” he says. “The maximum profit comes from having the entire system working for maximum efficiency, not from cutting on the inputs.”

Moore agrees, saying growing media mixes can have several impacts on financial stability.

“Most of which are not what people initially look at, such as the direct costs of the mix itself,” he says. “Yes, you can improve your bottom line by looking for ways to decrease the direct cost of the media itself, and the components that make it up. There’s a fine line, however, between saving a few bucks on mix quality, and losing a lot of dollars by then producing a crop with a higher shrink value or a poorer quality crop that impacts the ability to sell through better and/or at a higher price.”

Lucas Greenhouses uses Riceland Foods’ rice hulls product, PBH, in many of its mixes. When the operation first looked at the product, Moore says they were pleased with some of the cost savings compared to perlite, but that wasn’t the most important factor.

“If it would have negatively impacted our soil mix, we would never have worried about saving a few bucks but giving up quality,” he says. The product being a renewable resource is another positive benefit, he adds.

Still, because retaining financial sustainability is important to every grower, it is important to consider the optimal economic scenario for your operation, in addition to the ideal cultural properties. Factors determining the cost of a growing medium include transportation, labor, equipment, materials, and handling, among other considerations. Growers who are considering investing in equipment to mix their own blends may not realize that this option can be costly in comparison to buying commercially prepared materials. These factors must be studied carefully before making a decision.

Growing media manufacturers seem split on this topic. While some say the cost of growers custom blending their own material is underestimated, others say that’s a fallacy.

Moore says for Lucas Greenhouses, the ability to invest in a high-quality in line mixing system has been about more than cost.

“We can make all of our own mix here, and we have the ability to make many different types of mixes, so we can tailor mixes for the specific crop,” Moore says. “This is a massive advantage over having to grow everything in one or two different mixes. We can adjust pH and porosity, add time-release fertilizers if we want or need to, and add special additives.”

For growers who have not invested in mix lines, either due to the investment involved or preference to buy pre-mixed blends, growing media manufacturers now offer the added flexibility of producing a custom recipe as a service.

3 Things To Know About Growing Media Suppliers

1. Many of the larger mix manufacturers will have a handful of standard mixes, but they also offer hundreds of custom blends suited to growers’ preferences.

2. You don’t have to be a big operation to get a custom blend. “It used to be you had to be really large in order to get the customization, but with the computer controls on some of this equipment, you can dial it in much more readily,” says Bill Fonteno, Professor in the Department of Horticulture Science at North Carolina State University.

3. Quality is their forte. Mix manufacturers have invested in the equipment and personnel to ensure a consistent, high-quality product.

Value For The End Consumer

Ultimately, whatever choices growers make about the components that go into their growing media mixes will impact postharvest plant health and shelf life at retail and subsequent plant sales based on these factors, and plant performance in the consumers’ garden or home. Miguel Meneses of Jiffy Products International says when it comes to selecting growing media, growers don’t place enough emphasis on the success of the end consumer. That’s something he says he’d like to see change going forward.

“Growers tend to buy substrates that make their life easier at the nursery, but that is often the least challenging environment plants have to face, with all those professionals taking care of them, in a benign climate, with automation, etc.,” Meneses says. “The difficult part begins when we ship the plants away and expect them to perform well in a windy location, and have less prepared people making decisions about watering or not. Ironically, that’s when your plant should look the best. Retail, transplant, or home conditions are the real challenges.”

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2 comments on “Why You Need To Know What’s In Your Growing Media Mix

  1. This is an interesting article, but the major mix manufacturers all require truck load quantities for a custom blend. This limits custom blends to only the medium to large growers. Most small growers can’t afford to take a truck load of a custom mix.

    I also use Rice Hulls in my mixes. I despise perlite because of how dusty and unsightly it is. It is a non-renewable, non-decomposable product. I have replaced it in all of my mixes with rice hulls.

    Fafard, Premier, Berger and all of the others will NOT mix rice hulls in ANY of their mixes, even if they are in their catalog. I have called and asked for a price. Fafard (Sungro) outright said no when I asked for Rice Hulls. They said the cost of shipping is too high. Premier was willing, but I had to ship the rice hulls to them (Canada) and then pay to ship the completed mix to the farm. It is cheaper to do it myself or work with a local company.

    I have lately been working with HSU growing supplies in Wausau, WI. They will custom blend down to individual loose fill sling bags. They will also blend rice hulls with just about anything and incorporate just about anything. I am sourcing some of my mix from them and it is a time saver.

    Articles are good as it gets growers thinking. What I find troubling is that the big mix sellers don’t want change. They don’t want custom mixes. It cuts into their existing lines which they are streamlined for. Those that would like to tailor their mixes would do well to get some equipment to do it themselves or see if there is a local growing supply company that may already have this equipment.

    1. Hi Matt: Please consider contacting Mike Faust – Jolly Gardener ProLine / Oldcastle Lawn & Garden. We’ve partnered with Profile Products, referenced in the article as the manufacturer of Hydrafiber – a new substrate alternative. We also produce rice hull mixes for other growers today. We’ll produce custom blends in quantities as small as 6 pallets – not full truckloads. Our closest production plant to you is just outside of Chicago.


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