Growing Media: To Mix Or Not To Mix
Saving money isn’t the only factor you should consider if you’re looking at foregoing commercially manufactured growing mixes to make your own. There’s a lot more to producing growing media than purchasing the components and the equipment to make them.
Ed Bloodnick, director of grower services and product development at Premier Tech Horticulture, says regardless of whether a grower is mixing his own or buying a commercial mix, he needs to look at the plant species being grown, the stage of development, the container size and culture requirements.
“At certain times of the year, these factors are going to have an impact on the plants,” Bloodnick says. “Understanding the needs of the plants and these other considerations will determine the mixes a grower is going to blend or purchase.”
Consider The Headache Factor
Bloodnick says one issue that growers may not consider is the headache factor.
“By buying a commercial mix, there are a lot of things growers don’t have to worry about,” he says. “If you are buying a mix, it is usually much simpler to store the product. If you are mixing your own, you have to have the space for all of the components, for the equipment and for the mixed product. There is the ordering involved with the different components, handling them when they arrive and mixing them. You have to be able to maintain the inventory of components to be sure they are there when you need them.”
Bloodnick says commercial media manufacturers are in the business of making mixes, so they realize an economy of scale for production that may not be available to all growers.
“The start-up costs can make mixing your own very expensive,” he says. “For large-size growers, it may make sense for them to mix their own. But that doesn’t always hold true, because we have large customers who have told us that they don’t want to mix their own media. They say it’s not worth it.”
Dan Jacques, technical service manager at Sun Gro Horticulture, says growers who are buying a commercial mix are looking for quality, consistency and a mix that meets their needs.
“Usually they don’t want to invest the time, money and labor that it takes to make their own mixes,” Jacques says. “Growers usually make their own or buy in, one or the other. There are not a lot of growers who do both.”
Even Soil Can Go Bad
Whether a grower makes his own mix or purchases a commercial product, Bloodnick says there can be issues of freshness if a mix or the components are stored for too long. He says it usually takes most peat-based mixes nine to 10 months from the manufacture date to start to change.
Jacques says storage conditions are going to have a major impact on both commercial mixes and mix components.
“If they are stored outside, whether it is a finished product or one or more of the components like bark or peat, their properties are more likely to change over time,” he says. The wetting agent is still going to be viable, but it won’t be 100 percent of what it was when the mix was fresh. A mix should be stored under cool conditions and away from excess moisture. Even under these better storage conditions, lime and fertilizer in the mix will start to react. Optimizing storage conditions will minimize this reaction.”
Jacques says a mix with a controlled-release fertilizer incorporated should be used within seven to 14 days of the date that the mix was produced. He says once a mix with a controlled-release fertilizer is a few weeks old, regardless of the storage conditions, a grower needs to handle it carefully to make sure the soluble salts aren’t too high.
Going Online With An Inline
Lucas Greenhouses in Monroeville, N.J., has been operating a Bouldin & Lawson Mixmaker continuous soil mixing system for about three years. Prior to producing all of its media, the company was making about half of its mixes and buying the other half. The company operates 25 acres of heated production space and more than 30 acres of outdoor growing area.
Lucas Greenhouses’ Head Grower Joe Moore says the company made the decision to make all of its mixes, because it offered him more control over how and when the mixes were made.
“With the system we have installed, I can make any mix I want and I can tweak it anyway I want,” Moore says. “The cost savings are fairly substantial, as long as you have the capital available for the equipment. When you are making a mix with something like a 2-yard twister mixer, the cost is nowhere near as drastic as when you put in an inline system like ours. An inline system gives you the ability, as long as you are paying attention to it, to make a mix as good as or better than what is produced by a commercial manufacturer. Our growing mixes go directly into production, so they are fresh and don’t sit around.”
Moore says it may be difficult for a small- or medium-size grower to justify the cost of putting in an inline mixing system. Lucas built a 55,000-square-foot production barn that was designed completely around the inline mixing system.
“If you can’t make that kind of investment, then you really have to think twice about whether you want to go the mix-your-own route,” he says.
Moore says he expects that most large growers could produce their own mix cheaper than the price they pay for pre-mixed media. A large grower should expect a payback on the equipment in three to five years, depending on mix volumes produced.
Pay Attention To Details
Lucas Greenhouses has one person in the production barn that ensures the mixing line is running smoothly.
“The quality control person walks along the line to be sure everything is operating the way it should,” Moore says. “The bins have sensors on them, so if the bins run out of a component or drop too low, an alarm goes off and actually shuts everything down.”
Growers who are considering mixing their own need to include a financial figure for testing or quality monitoring when determining costs, Bloodnick says.
“You should really confirm what is going into your mix, whether you test it yourself or send it to a lab for testing,” he says. “We like to see growers who are mixing their own test for pH, electrical conductivity (EC) and some independent laboratory tests as confirmation. In addition to our quality assurance lab tests, we take batches of growing mix and grow plants in it at our greenhouses. But this doesn’t take into account some of the variables that can change over time with product age.”
When it comes to the consistency and the backing of the product, Jacques says most mix manufacturers stand behind their products and will work with a grower to resolve an issue, whether it is related to the growing mix or not.
“If a grower makes a mistake making his mix and it impacts his crop, most growers don’t have someone they can quickly turn to for assistance with the problem,” Jacques says. “If the grower needs a consultant to come in, there is a cost associated with that. Generally there are a lot of hidden costs that growers don’t take into account when they decide to mix their own.”