Hydroponics for a changing market

Hydroponics is like a kid in school looking to find a way to fit in. While the technology to produce crops hydroponically — in soilless substrates and using nutrient-rich solutions that go directly to the plant roots — has been around for a long time, its usage has been more novel than practical.

That, however, is changing. Health-conscious consumers with increasingly sophisticated tastes are prompting more farmers to consider, or reconsider, covered cropping to grow an increasingly diverse number of organic vegetables. This appears to be particularly true in the southern states and locations near large population centers, such as Orlando, Fla.

“The biggest advantage between growing under cover versus growing outside is keeping the crop out of the weather,” says Dan Cantliffe, professor, Horticultural Sciences Department, University of Florida’s Institute of Food and Agricultural Services (UF/IFAS).

Cantliffe points out a number of advantages to covered cropping including less use of pesticides, protection from the elements, and, in Florida markets, being able to grow colored peppers. In short, he says, you have “more control over the environment.” Covered cropping for hydroponic production includes high and low tunnels, vented greenhouses, as well as the use of cooling pads and shade cloths during the heat of summer.

The increase in hydroponic production in Florida reflects an upward trend in hydroponic production in this country and internationally. Robert Hochmuth, multicounty extension agent, Suwannee Valley Agricultural Extension Center, said a soon to be published survey done by the University of Florida reveals there are now 400 acres of land devoted to covered hydroponic production in the state, compared to the 100 acres noted in a 2001-2003 survey. He says most of this growth has occurred in the past five years.
 

No walk in the park

Starting up a hydroponic growing operation is not easy –or cheap. The initial investment in coverings and hydroponic growing equipment is high and the learning curve is not only sharper, but also differs from conventional farming.

“People have traditional farming skills that don’t transfer to hydroponic growing,” says Hochmuth. “It’s important to get preliminary training before spending a lot of money.”

It also costs more to grow a crop hydroponically. This means growers need to retain 50 to 100 percent of the retail value of the crop, according to a report titled, “Hydroponic Vegetable Production in Florida,” by Hochmuth, Cantliffe, and Richard Tyson, county extension director, UF/IFAS.

To make a profit, it is important to know your markets, says Hochmuth, whose “Top 10” things to know about hydroponics is largely comprised of marketing tips. Selling directly to retail markets, including farmers markets, is one way to make hydroponics profitable, he notes.

“It takes a real commitment of time and energy; it’s a lifestyle” adds George Saridakis, president, International AquaFoods Corporation Seaburst Farms / Olive Creek Farms in Woodbury, N.J. Saridakis grows basil, leafy greens, and tomatoes under cover in a greenhouse at Rutgers University and sells to several corporate clients.

Fortunately, there are many good resources to reduce the learning curve for farmers wishing to get into hydroponics on a small or large scale (see below).
 

A changing market

Hydroponic production in Florida and other locales has changed in the last 15 years. While tomatoes and peppers are still mainstays in hydroponic operations, several more food items are being grown, including lettuce and other greens, micro greens, herbs, cucumbers, and strawberries, according to Hochmuth. This diversity in fresh vegetable and herb offerings is being spurred on mostly by consumer demand, particularly shoppers who frequent farmer’s markets and roadside stands.

The changes are also being felt in some of the more northern states. Saridakis says he sees quite an interest in hydroponic production from growers he’s acquainted with, despite the need for supplemental heating in the north, which drives up costs. Hochmuth currently uses the heat produced from methane gas from a nearby landfill, and a natural gas backup. He says some growers in New England are heating with wood-fired boilers.
 

Plethora of options

Presented here are the many and diverse systems used for hydroponic growing.

Floating raft systems. This is perhaps one of the easier and cheaper hydroponic growing systems with which to get started. This relatively new system for hydroponic growing works well with short season, shallow rooted crops including lettuce, basil, and watercress. These crops grow well under high moisture conditions. The floating raft system utilizes Stryofoam “rafts” and a vessel to hold water, which can range from a children’s swimming pool to a 4- x 8-foot frame lined with 6-mil polyethylene sheeting. These systems are currently being used on hydroponic farms in Florida.

Vertical towers. Growing vertically is a good way to save space in the greenhouse. With this system, which is most suitable with strawberries and leafy vegetables, six to eight containers are stacked one atop of the other with a pole through the center for support. A nutrient-rich solution is poured through the top container and trickles down to each container underneath via drainage holes. The liquid exits the bottom where it can be reused.

Ebb-and-flow system. This system of hydroponic growing, which is easy to construct and maintain, is also known as a flood-and-drain system. The main goal of the ebb-and-flow system is to maximize nutrient uptake and available oxygen to the plant’s root zone. The most basic ebb-and-flow system uses one pump to deliver nutrients to the root zone, and gravity to return the solution back to the reservoir (the growing tray is located above the reservoir and pump).

Recently, growers using the ebb-and-flow system have realized the potential benefit to using a dual pump system. With this system, which doesn’t require gravity to return the nutrient solution to the reservoir, everything can be placed on the floor, thus maximizing space for tall plants, such as indeterminate tomatoes.

Nutrient film technique. With this technique, which some growers refer to as a true hydroponic system, nutrients are delivered via a shallow film of water along a water tight gully that slowly moves a solution past the root zone of the plants. This ensures that the thick root mat that develops in the bottom of the channel has an upper channel that is moist, but nevertheless in the air. To work properly, an NFT system needs to have a channel with the correct slope, flow rate, and channel length. When properly designed and installed, an NFT system will expose the root system to adequate supplies of water, nutrients, and oxygen.

The main challenge of this system is the extensive root system that can develop with some plants, making it difficult for the solution to flow through the channels.
 

Substrate options

To ensure proper aeration and to prevent the clogging of the irrigation system, substrates for hydroponic production must provide adequate pore size. Here are the options with which growers should be familiar.

Coconut coir. Coconut coir is increasingly being used in conventional greenhouse growing and is also gaining attention from hydroponic growers. Cantlisse says Florida hydroponic growers are turning to coconut coir due to the availability and price as well as its ability to deliver. Coco coir, as it is also referred to, provides better aeration than rockwool and has a higher water holding capacity.

Soilless potting mixes. Peat-based mixes used in conventional greenhouses are also used in hydroponics and can have different compositions of perlite and vermiculite. Peat-based mixes, which includes peat moss harvested from bogs in northern Canada, are available and reasonably priced, though they may not be suitable for specific hydroponic growing systems.

Perlite and vermiculite. Perlite is the white “popcorn” type substance found in traditional potting mixes. It is a chemically inert substance that provides high porosity and aeration to plant roots. Vermiculite is used for its water holding capacity. It has a natural wicking property that is capable of soaking up three to four times its volume in water. Both are commonly used in hydroponic production.

Neil Moran is a horticulturist and freelance writer based in Sault Ste. Marie, Mich.

For more:

Hydroponic systems
University of Florida’s IFAS Extension (http://edis.ifas.ufl.edu/hs405)

“Virtual Field Day” videos of hydroponic systems produced by UF/IFAS,
http://vfd.ifas.ufl.edu/index.shtml.

Greenhouse structures
Atlas Greenhouse Systems
http://www.atlasgreenhouse.com/

Farmtek
http://www.farmtek.com/farm /supplies/home

HiredHand
http://www.hiredhand.com/

Seed for hydroponic production
https://www.paramountseeds.com/