By Bobby Barnitz | August 13, 2015 | Source: GreenhouseGrower.com

My father started our company 45 years ago growing bedding plants, mainly early season production and finished plants for our West Virginia market. It was in the early 1980s that we started growing earlier spring production and shipping materials to southern markets, and by the late 1980s, we also produced pansies for fall.

We started using hydrogels when they first came on the market in the early 1990s and found that they really helped with our production by keeping plants healthier for these new markets.

Over the years, we’ve grown to be a large young plant producer and have a sizable business growing finished plants in cell packs, 4 1/2-inch pots, 6-inch pots, gallon containers, hanging baskets, multiple sizes of large containers and large baskets for municipal use.

Creating The Ideal Soil Mix

With our old system, it took several workers to mix pre-made soil with slow-release fertilizers in cement mixers, and then blend in the hydrogel material. Even though the granules are the size of sugar, they expand in the soil when they absorb water.

We experimented with the idea of pre-hydrating the hydrogels by filling a number of flats with dry hydrogels and adding water, while filling other flats with pre-hydrated hydrogels mixed into the soil.

Bob’s Market and Greenhouses’ Ron Morris pours Stockosorb into the hopper for distribution on the conveyor line

We knew that hydrogels improved plant quality from the very beginning, because we tested African Marigolds both without hydrated hydrogels and with them. To establish, we used the same amount of water on both sets of plants, but once the roots established, we saw greater benefits. The roots grew through the gels and the plants didn’t wilt as quickly. We saw that they were less stressed and were higher quality plants, and less apt to be diseased. Our customers also realized that we had made changes to our soil mix without us telling them. The plants required less water than before.

After several trials, we realized that by adding pre-hydrated hydrogels into our soil mix, we had created a better soil mix, with lower cost inputs and the opportunity to reduce our labor costs.

Our business continued to grow, and around three years ago, we looked for ways to reduce our labor costs for soil mixing by automating the process. We committed to a soil line vendor at Short Course in July that year, and they designed a computerized mixing and distribution line to retrofit into our operation that would minimize input costs and give us more consistency. We also use Stockosorb hydrogels from Evonik Corp., working closely with them, using their samples to determine the type of equipment and method of distribution to use for the mixing line.

By October, we were busy expanding our building for the line and had the automated line partially installed and tested by December — almost ready for January production to start. It was only a six-month process.

A diagram of the hopper, the delivery rate is controlled by the speed of the auger and conveyor.

How The Mixing Line Works

The 100-foot mixing line starts with a series of hoppers above that dispense components of the growing media onto a conveyor line below: peat, rice hulls, hydrated Stockosorb, perlite, pine bark and other low volume additives (lime, nutrients, fungicide, etc.).

The hydration of the hydrogel is critical to this system. We use purified water to get maximum hydration of the Stockosorb, and rely on a Rainsoft commercial water softener with reverse osmosis to get the purification level we want. We place 15 ounces of Stockosorb in a clean, 15-gallon plastic container and add 13 gallons of the purified water, letting it sit for around 40 minutes to hydrate. We use different sizes of hydrogel particles, depending on the application — the smallest size for cell packs and the larger size for large pots. Whatever the size, they will be distributed uniformly by our system.

Once the material is hydrated, the container is tipped into the hopper, which is fitted with an auger to move the hydrated hydrogel through to a layer on the conveyor belt, and then moves on to the perlite and pine bark hoppers. Once all components are layered onto the belt, they progress to the mixing hoods for thorough mixing. The mixed materials then are transported to the dispensing section of the belt. Sensors monitor the dispensing into flats and containers for consistent filling.

As for maintenance of the hydrogel mixing hopper, all we need to do is give it a few blasts of compressed air. The material does not wear down the stainless steel auger.

The plants that benefited the most from pre-hydrated hydrogels were those grown in larger containers.

Benefits For Growing And Selling

This was a serious investment for us, but it quickly paid for itself through labor savings, reducing the number of workers needed from six people to one. It is a safe, automated system needing minimal work and providing consistent mixing.

The soil blending line has benefitted our growing operations as we continue to produce healthy, high-quality crops.

The plants that benefit the best from the hydrogels are our larger containers, which are a huge part of our business. This in turn really helped our customers, because with our product on their tables, the plants survived longer, and our customers had less shrink (and therefore, more sales).

Plan Ahead For Automation

Many growers visit us to see this line and ask how they can incorporate these ideas. My advice is to plan ahead when you design a soil mix system, consider all the mix components you’ll want to use and look at your costs. For us, this solution was a great way to cut costs and improve our plant quality.