August 2002

Hydroponics: Successful Surfing By Elizabeth Pensgard

Hydroponics was once thought simply to be the growing ofplants without soil. It has since evolved into a science–the growing ofplants in a nutrient solution with or without an inert medium such as gravel,sand, peat, vermiculite, perlite, rockwool, coir or sawdust–and onethat requires specific knowledge, capital and perhaps a bit of fearlessness.

Another derivative of evolving modernity is the Internet,which some would say also requires a bit of savvy and fearlessness. However,nowhere is there such an amassed amount “f information so readily available ason the World Wide Web. Following are listings of Web sites that GPN founduseful for the beginner or the established hydroponic vegetable grower, as wellas for those on the fence.

Why or why not hydroponics?

It is always a good idea to know all the benefits gainedfrom beginning or switching to a different technique. The pros of hydroponicsare endless and include fewer soil-borne pests and diseases, no weeds, lesslabor-intensiveness, greater plant allowance within a smaller space, morequickly grown plants with higher yield, water and fertilizer conservation andmore control over nutrient levels and fertilizer absorption(www.archimedes.galilei.com/raiar/histhydr.html).

Yet, with advantages come disadvantages. In a more basic,just-the-facts-ma’am type of site simply entitled”Hydroponics”(www.oswego.edu/nova/facts/hydroponics/hydroponics.html), some of thedisadvantages along with the advantages are outlined as well as pros and consof various kinds of media and hydroponic system types. The site notes thatwithout question, one of the biggest drawbacks of hydroponics is the cost, bothfor the initial capital investment and for the advanced heating, cooling andirrigation systems required.

General overviews

If you are a beginning grower, or even if you’re not,it is sometimes advantageous to begin with the basics. The Greenfingers site(www.greenfingers.com.au/services/digging_deeper/growing_hydroponic_veg.htm) byMalcolm Campbell is a good place to start. He gives a general overview ofhydroponics and discusses the pluses and minuses of using hydroponics, the useof different types of media, various locales for your hydroponic crop andsowing techniques.

The Foothill Hydroponics Library site is also a good sitefor beginners, or for those who need a reminder of why they initially chosehydroponics. The site offers a very helpful brochure called The 5 Ws ofHydroponics (www.foothillhydroponics.com/brochure/

5ws.htm). Questions addressed include : Whyhydroponics? When do I use hydroponics? Where canhydroponics be used for maximum benefit? How can I actually usehydroponics? What is a growing media? and Whichtypes of systems may be used for hydroponic irrigation? Also found onthe site are other links to articles and brochures with diagrams andrecommendations for the beginner.

Commercial hydroponics

Beginning a hydroponics business, or adding hydroponics toyour existing operation, is never an easy task. Like all start-ups, the oddsare stacked squarely against you. You should consider your market, skill level(both in growing and in management), growing environment, financial standingand the amount of sweat equity required. A good summary of things to considercan be found on the Practical Hydroponics & Greenhouses Web site atwww.hydroponics.com.au/back_issues/issue06.html and www.hydroponics.com.au/back_issues/issue07.html.

Hydroponic techniques

In addition to knowing the basics, it is important to beaware of the different hydroponic techniques and discern which one adequatelymeets the needs of your particular situation. While the general overiews aregood sites from which to glean basic information, they are limited in terms ofintermediate to advanced hydroponic growers’ needs. Aquamist, ahydroponic products store, describes the various kinds of hydroponic techniqueson its site (www.aquamist.com/hydroponics), and while the information is stillsomewhat basic, it provides a good stepping stone to choosing the righttechnique for your operation.

A discussion of hydroponic techniques would be remisswithout also discussing a somewhat recent technology called aeroponics inwhich, according to the International Society for Soiless Culture, “rootsare continuously or discontinuously in an environment saturated with fine drops(a mist or aerosol) of nutrient solution”(www.hydroponics.com.au/back_issues/issue05.html). This technique, thoughproven highly successful, is often not used by commercial vegetable growerssince it is initially costly and perhaps overly mechanical and delicate forsome growers.

Growing hydroponic vegetables

Though growers can grow almost anything hydroponically,there are certain vegetables that perform exceptionally well in pricingstudies. Those top performers are typically high-quality salad crops–tomatoes, cucumbers, lettuce, spinach–that have been shown to providebreak-even or better revenues in hydroponic systems(www.ag.arizona.edu/hydroponictomatoes/overview.htm).

Tomatoes are the highest of the top performers, according tothe University of Arizona. They are one of the most commonly grown hydroponicvegetables since 4.3 billion tomatoes are consumed in the United States alone.Due to the relatively high cost of hydroponic growing, tomatoes are among themost likely crop to recoup the extra expenditure in capital, automation andenergy costs required for hydroponics. When consumers are willing to pay 2-3times more for a better tomato, hydroponic tomato growing can be highlylucrative. On its site, Growing Tomatoes Hydroponically(www.ag.arizona.edu/hydroponictomatoes/overview.htm), the University of Arizonarecommends greenhouse and environmental control system types, offerspropagation techniques, illustrates proper growing media for plant types, plantnutrition, pest and disease control and provides harvest information forhydroponic tomatoes.

North Carolina State University (NCSU) and Mississippi StateUniversity also offer wonderful sites (www.ces.ncsu.edu/depts/hort/greenhouse_veg/topics/topics-pages/GH_Tomato_Production.htmland www.msucares.com/pubs/pub1828.htm, respectively) devoted to hydroponictomato production, though you will need Adobe Acrobat to view thepresentations. NCSU lists statistics, common grower problems, types of tomatocrops that can be grown, costs and possible returns on investment, andrecommends the best growing media, structures, production systems, growingtimes, insect population monitoring systems and insect biocontrols. MSU offers varietyinformation, pruning advice, temperature, humidity and pH recommendations, aplanting schedule and lists nutrition deficiency symptoms.

While tomatoes are the most common hydroponically growngreenhouse crop, growers also grow lettuce, spinach, cucumbers and otherveggies. For a listing of several Web sites for commonly grown hydroponicvegetables, including tomatoes, cucumbers and lettuce, visit the University ofFlorida’s research and education site atwww.nfrec-sv.ifas.ufl.edu/gh_&_hydroponics.htm#GH%20Crops. Though directedprimarily at Florida growers, the information is still pertinent to mostgrowers? needs. The University of Florida also illustrates effectivecucumber and tomato growth using perlite media (www.nfrec-sv.ifas.ufl.edu/keys_to_success.htm)and has several links devoted to seed sources, greenhouse design, nutrientsolution formulation and their own vegetable production handbooks(www.nfrec-sv.ifas.ufl.edu/gh_&_hydroponics.htm).

Cornell University, like the University of Arizona, NorthCarolina State University and the University of Florida, has its own controlledenvironment agriculture program. The program grows hydroponic lettuce, spinachand pak choi. Their lettuce, spinach and pak choi handbook sites are located atwww.bee.cornell.edu/extension/CEA/LettuceHandbook/Lettuce%20Intro.htm;www.bee.cornell.edu/extension/CEA/Spinach_Hanbook/index.html; andwww.bee.cornell.edu/extension/CEA/Pakchoi_Handbook/index.html, respectively.The sites offer greenhouse hardware and environmental control systemrecommendations and advice on production, transplanting, crop health, harvestand postharvest procedures. Also available are images of various growth stagesfor each vegetable.

Proper electrical conductivity and pH levels for hydroponic vegetables

The GTG Hydroponics site(www.gtghydroponics.com/veggiph.htm) is an excellent resource for determiningthe proper pH level of the particular hydroponic vegetable you are growing.Once you have determined the proper pH for your particular crop, consultPractical Hydroponics and Greenhouses’ article “Calibrating pH& Conductivity Test Pens”(www.hydroponics.com.au/back_issues/issue09.html) to learn how to properlymeasure the pH and electrical conductivity of your crop.

Also discussing the proper way to measure for pH and EC isthe University of Massachusetts’ site(www.umass.edu/umext/programs/agro/floriculture/floral_facts/phecpens.html).The site describes how to calibrate and use the “pen” correctly tomeasure pH and EC, and lists additional supplies needed. In addition to theproper use of the pen, the site explains how to extract growth medium samplesand interpret the test data. The site is based upon bedding plant data, but thedirectives are the same for hydroponically grown vegetables, with the exceptionof pH levels, which should be predetermined for the particular vegetable youare growing.

Nutrient management

Practical Hydroponics and Greenhouses is also an exceptionalresource for nutrient solution management of hydroponic vegetables, and offersa 4-part article on issues concerning proper nutrient management. Part oneintroduces the principles involved in nutrient management, though it is notavailable on the Internet and must be requested directly. Similarly, part twodiscusses the general principles of nutrientmanagement, including water quality, fertilizers andnutrition in open and closed conditions (www.hydroponics.com.au/back_issues/issue14.html). Part three concernsrecirculating systems and discusses the two different kinds of closedrecirculating systems as well as different management techniques, EC and pHcontrol, water quality, the dumping of extraneous nutrient solution, bleedingand waste management (www.hydroponics.com/au/back_issues/issue16.html). Partfour of the article, dealing with management of open or non-recirculatingsystems, is also unavailable on the Web site and must be requested directly.