Greenhouse Vegetable Production Systems for Every Grower
Greenhouse vegetable production has never been easy. With rising production costs, expanding environmental regulations, and a diminishing labor force, now more than ever growers are forced to be innovative. Thankfully, growers have an increasing number of tools at their disposal.
“There’s no one-size-fits-all method; I’ve seen many growers producing great crops in different ways,” says Joe Swartz, Vice President at AmHydro and a controlled environment agriculture consultant with more than 30 years of hydroponic growing experience under his belt.
“We have all these available tools and technologies, so it’s about finding the right fit. The results are what counts.”
Swartz says the key to any growing system, however, is two-fold. The systems need to be based in sound horticultural production techniques, and they need to be efficient. When it comes down to it, he explains, controlled environment agriculture is a real estate game. Growers will always be limited by their production space. The right system will help them manage it effectively while minimizing production costs.
Here are some of the latest and greatest options for growers to consider.
NFT and Hydroponics Systems
NFT technology has come a long way. While the traditional method uses channels to stream water and dissolved nutrients directly to plant roots before recycling and recirculating the unused materials, most commercial greenhouses have taken the basics of this system and made improvements.
lef Farms, for instance, uses a hybrid NFT system that helped the salad greens grower conserve resources and speed up its production process. Instead of rockwool, lef Farms uses peat moss to reduce pest populations and to create a compostable bi-product that’s sustainable and won’t end up in the landfill. This isn’t the only difference.
According to Rough Brothers’ Tom Vezdos, another option is a fully automated NFT system that uses conveyors and lifts to move the crops through the different stages of the cycle, from germination to harvest. The addition of automation helps eliminate the labor issues that can sometimes be associated with traditional NFT where every step of the process is done by hand.
Vezdos also likes deepwater culture (DWC) systems. DWC is sometimes called hydroponics in its purest form, as it doesn’t require growing substrate growing. The plants roots dangle directly into pools of nutrient-rich aerated water.
“Nowadays, there’s automation that allows growers to virtually eliminate the need for people,” he says, adding that DWC with a raft system works well in a large-scale operation. “The benefit is that DWC has a large mass of water and isn’t susceptible to whether a pump is running. If there’s a mechanical issue, the system maintains its integrity. You simply push the rafts to where you’re doing the work.”
While traditional NFT systems are primarily for leafy greens and herbs, bucket and vine crop systems offer a closed-loop system for larger root crops like tomatoes, peppers, cucumbers, eggplants, and more. In these systems, the roots are contained in a soilless media instead of a channel. Swartz says these systems used to be “drain to waste,” but ones like AmHydro’s now close the loop and recycle the unused nutrients.
Even hydroponic growing substrate has gotten more advanced. Oasis Grower Solutions, for example, offers a hydrophilic foam medium that contains starter nutrients, an Easy Plant system of products that include the plug, block, and slab for hydroponic crops such as tomatoes, and one-bag hydroponic fertilizer. “Hydroponics will see explosive growth in the next few years,” says Oasis Global Marketing Manager Jeff Naymik. “As the cost/value of land increases, governmental changes and global demand will put pressure on growers to increase turns in less space while increasing the yield per square meter.”
Many growers are eager to find NFT upgrades, but others are happy with the traditional systems. Great Lakes Growers loves that its hydroponics system allows it to grow produce year-round in Ohio. Co-owner Tim Ryan says this system uses less water than both raft systems and traditional outdoor farms.
“The water we do use all gets recirculated and re-nutrified and sent back out to feed the plants, meaning we don’t send anything down the drain or run excess water outside the greenhouse into rivers, streams, etc.,” Ryan adds.
“Our system also allows for fine tuning of pH and fertilizer content on a continuous basis. And we have very good airflow from underneath our NFT benches, which some other hydroponic systems cannot provide. This is beneficial to the health of the plants.”
NFT and their upgraded counterparts have obvious benefits, but as with any system, there are drawbacks, as well. Automation is never cheap, and there’s an ongoing debate about whether the NFT-grown vegetables could ever be as tasty as their field-grown counterparts.
For those who want to grow organic, however, the biggest con is that substrate media can’t meet the standards for certification. Ryan explains that fertilizer can also pose a problem since natural animal byproducts like cow manure could expose the produce to animal-based diseases, but synthesized options won’t meet organic certification requirements.
When hydroponics systems met aquaculture, the result was aquaponics: A symbiotic relationship in which fish waste is converted to natural fertilizer that nourishes plants. One of the major benefits, says Rebecca Nelson, Co-founder and Co-owner of aquaponics manufacturer Nelson and Pade, Inc., is that growers can produce a protein source and a green crop in one small body of water.
“With aquaponics, you can grow almost any vegetable,” Nelson explains, saying that she’s worked with growers who have produced everything from sweet corn and green beans to kale and swiss chard. “Because most crops don’t tolerate salt water, aquaponics typically produces freshwater fish. The most common is tilapia. It’s very hearty and thrives at 74 degrees, the same temperature as plant roots.”
The other big benefit to aquaponics is that the fish produce a completely natural fertilizer, which allows growers to save money on that input. While growers would need to purchase fish food (and feed the fish multiple times per day), they won’t use pesticides, herbicides, or any contaminants throughout the process.
The most difficult thing about going the aquaponics route is that the system requires someone to monitor the system seven days per week. As Nelson puts it, if there’s a problem with the hydroponics equipment, you could lose a vegetable, with aquaponics, you could lose a fish.
Even with an automated, science-based design with backup generators, growers will encounter a learning curve. Integrating two very different systems can be tricky, especially on a commercial scale. Nelson and Pade offers long-term grower support for how to use the systems. Anyone interested in making their green business sustainable would want to consider working with a manufacturer that offers the same.
Vertical Growing Systems
For some growers, the future of farming is vertical. This growing method turns traditional production methods on their sides, stacking plants on top of one another to better optimize space. The method has been particularly popular in urban spaces where real estate is a hot commodity — and fresh produce is a rarity.
At the 2017 Global Innovations in Horticulture Seminar, Wageningen University’s coordinator innovative technologies and guest speaker Frans Kampers identified another promising feature: The innovative technology is getting young people interested in the green industry.
According to “Vertical Farming Could Take Horticulture Higher,” a recent article on GoodFruitand Vegetables.com , Kampers says, “There are parts of the world where it is very difficult to get young people to take over the farm. If we can include more technology, it will involve less heavy work and will be more interesting for young people to do.”
Still, some experts remain skeptical that the technology delivers on its promises.
“The problem with tower systems is that you’re always robbing Peter to pay Paul,” Vezdos says, adding that even with innovations in light wave diffusion technologies, there will always be a portion of the tower that’s shaded. “Growers are going to struggle with uniformity issues.”
Swartz agrees vertical technologies aren’t as promising as they sound. He says he was fooled until he ran tests and closely examined the data. In his recent LinkedIn article (Going Vertical to Increase Your Yields? Let’s Look at the Realities. You might be Surprised!) on the topic, Swartz found that in a 30-foot-by-96-foot greenhouse, horizontal NFT channels produced 10,368 plants compared to 6,456 plants in vertical towers in the same space.
Another system that has caught people’s attention in recent years is aeroponics. This sunless, soilless system delivers air, water, and nutrients directly to the root zone. Aeroponics is known for its quick growth and compact space requirements.
Although this grow method has many small-scale successes, there haven’t been many commercial operations embracing the process. AeroFarms, a manufacturer of a patented aeroponic growing systems, wants to change this.
“We disrupt traditional supply chains by building farms on major distribution routes and near population centers,” the company’s website explains. “We defy traditional growing seasons by enabling local farming at commercial scale all-year round. . . . And we do it all while using 95% less water than field-farmed food and with yields 130 times higher per square foot annually.”
This method sounds like the perfect solution to a variety of farming-related problems, but Swartz says growers need to be cautious, particularly when scaling up to a commercial business.
“The technology is expensive and requires a high level of maintenance,” he says. “There are a number of mechanical challenges when growing this way. Most growers haven’t been able to find the right parameters to make this method cost-effective and productive.”
Finding the Right System
So, what’s the best system for growing produce? It depends. Growers need to ask several questions to get to the perfect solution. Geography, crop type, desired level of automation, and budget all play a role in what system makes sense.
Another important thing to consider is the end product. A technique that works well for tomatoes might not be the best for a cut salad mix. Manufacturers are willing to work with growers to build the best systems for their operations, and many offer technical support to ensure employees know how to properly use the equipment. Ultimately, there’s no perfect system.
“I’ve been hearing that hydroponics is the future of food for 30 years, but that’s crazy,” Swartz says. “Controlled environment agriculture is just a technique. It’s no more legitimate than any other tools or techniques.”