Organic Greenhouse Vegetable Production - CiteSeerX

ATTRA // OOOORGANIC RGANIC RGANIC RGANIC GGGGREENHOUSE REENHOUSE REENHOUSE REENHOUSE VVVVEGETABLE EGETABLE EGETABLE EGETABLE PPPPRODUCTIONRODUCTIONRODUCTIONRODUCTION 111

By Lane Greer and Steve DiverNCAT Agriculture SpecialistsJanuary, 2000

Introduction

Although several Extension bulletins areavailable on greenhouse vegetable production,few of these concentrate on organic productionmethods. This publication presents an overviewof greenhouse production systems and profilesseveral farmers raising organic vegetables ingreenhouses. It is hoped this will give newgrowers ideas of how to set up their systems,and provide more experienced farmers withexamples of alternative methods of production.

The term greenhouse means different things todifferent people. A greenhouse used to be astructure formed of glass, with a heating (andusually cooling) system that was used year-

round, but especially in winter. Then camehouses built of thermoplastic (Plexiglas andothers), followed by Quonsets covered withplastic, which may or may not be heated, haveone or two layers, and be used year-round or foronly a few months every year. The type ofgreenhouse you have will largely be determinedby your crop and your capital and, to a lesserextent, by your management intensity and yourmarket strategy.

For the purposes of this publication, agreenhouse can be any of the above. AnotherATTRA publication, Season Extension Techniquesfor Market Gardeners, contains furtherinformation on protected shelter structures suchas cold frames, high tunnels or “hoophouses,”and low tunnels.

800-346-9140

Appropriate Technology Transfer for Rural Areas

ORGANIC GREENHOUSE

VEGETABLE PRODUCTION

Abstract: Organic greenhouse vegetable production is regularly practiced by certified organic farmers andmarket gardeners, and has potential for wider adaptation by established greenhouse operators and entry levelgrowers as a niche market or sustainable method of production. This publication focuses on organic methods ofgreenhouse vegetable production, and it is supplemented with a listing of greenhouse resources.

ATTRA is the national sustainable agriculture information center funded by the USDA’s Rural Business -- Cooperative Service.

IndexIntroduction//Page 1The Greenhouse Vegetable Industry//Page 2How Can Small Growers Compete?//Page 2Organic Greenhouse Production//Page 4Soil vs. Soilless Culture//Page 7Soil Culture//Page 8Soilless Culture//Page 10Hydroponics//Page 12Variety Selection//Page 13Economics//Page 13Developments in the Greenhouse Industry//Page 14Summary//Page 15References//Page 15Seed Sources/Page 16Organic Fertilizer Suppliers//Page 16Resources//Page 16

HORTICULTURE SYSTEMS GUIDE


The Greenhouse Vegetable Industry

The U.S. greenhouse vegetable industry is amixture of small, family-run operations in the2,500 to 10,000 square foot range and a smallnumber of large, multi-acre facilities 10 acres ormore in size. The larger greenhouses often usewaste heat from a power plant or other sourceof cogeneration (1).

Current U.S. production estimates aresomewhere around 800 acres (2). Incomparison, Mexico has about 450 acres,Canada has about 1,600 acres, and Holland hasover 11,000 acres (3, 4). In the latter part of the1990s, Canadian greenhouse vegetableproduction grew at a rate of 20% a year. Howhas Canada been able to generate this hugegrowth? “Significant new greenhouse vegetableproduction technology that was transferred tocommercial producers has been primarilyresponsible for dramatic yield increases over thelast 7–8 years, estimated at 100–120% fortomatoes and 70–80% for cucumbers” (3). Canada is strongly supporting its greenhousegrowers, both with research and withinvestment dollars. Their research facilities atHarrow are recognized as topnotch the worldover. Although most Canadian greenhousevegetables are not produced organically, therehas been an emphasis of late to use IPMstrategies, rather than pesticides, toaccommodate the growing market of consumerswho want pesticide-free produce. Most of theorganic produce imported into the U.S. is nowcoming from Mexico.

Tomatoes are the leading greenhouse vegetablecrop, followed by European cucumbers, lettuce,peppers, and culinary herbs such as basil, sage,and rosemary. See the ATTRA publications onthese specific vegetables for more information. In addition, growers aiming at niche marketsraise specialty crops, greens, and Orientalvegetables.

The leading states in greenhouse vegetableproduction are California, Florida, Colorado,Arizona, Ohio, Texas, and Pennsylvania—allwith over one million square feet of productioneach (2). This is where the centers ofproduction exist, both as a source of competitionas well as a source of technical assistance. Small-scale growers who plan on direct marketsales may want to think twice before gettinginto this business in a region that is alreadysaturated.

How Can Small Producers Compete?

With so much competition from Canada,Mexico, and overseas, how can small farmersrealize a profit raising greenhouse vegetables? One issue of increasing importance toconsumers is vegetables grown with minimumpesticides. The public has also become educatedon the values of locally grown produce: it’sfresher, it tastes better, and it may even be lessexpensive, since there are fewer shipping costsinvolved. Also, money paid to a local farmer isre-invested in the local community and helps tokeep that economy strong.

Year-round production is key to maintaining thegreenhouse’s profitability. However, this doesnot necessarily mean that growers should beproducing the same crop year-round. (Wintertomatoes bring more money than do summerones.) Another option would be to raise a cropother than vegetables, like bedding plants forearly spring sales or poinsettias for Christmas. The grower may decide that the most cost-efficient way to use his or her greenhouseduring the summer is to shut it up to solarizethe soil and “cook” insects (and their eggs) thatare present.

Small growers must find niche markets. It ispointless to try to compete with massmerchandisers like Wal-Mart, because the smallgrower will always lose. What are some nichemarkets for organic greenhouse vegetableproducers? Some of the general niches havealready been mentioned: consumers are lookingfor organic, locally grown, early-seasonproduce. Whatever the niche market, it isimportant for growers to realize that the nature

Small-scale growers who plan on directmarket sales may want to think twicebefore getting into this business in aregion that is already saturated.


of niche markets is for them to disappear after awhile. Oversupply or lowered demand willcreate lower prices. The market will change tofavor one product and disfavor another. Thismay happen when mass merchandisers enterthe market, when the popular press promotes aparticular vegetable, or when new medicalevidence points to increased or decreased healthbenefits from certain vegetables.

A good example of changes in a niche market isthe salad greens industry. Fifteen years ago, leaflettuce was almost impossible to find. Whenleaf lettuces were introduced to the generalpublic, few people accepted them. When chefsin finer restaurants began using them, moreaffluent people began asking for them inmarkets. The undersupply led to extremelyhigh prices; as much as $16 per pound was notuncommon. More and more small growersbegan producing salad greens, but it wasn’tuntil large growers entered the market that theprice per pound went down significantly (to $6–10 a pound). Many growers can still get $4–6 apound for greens, but as more large growersenter the market, this price will continue todrop. Long before the market has bottomed outis when small growers need to diversify andfind ways to add value to their crops, likeoffering pre-cut, washed and ready-to-eat mixedlettuces. Labor and energy are usually the two greatestgreenhouse expenses. If small growers can finda way to decrease costs of either or both ofthese, their chances of making a profit arestrengthened. How can they do this? Cheapsources of energy are key. Sunlight,decomposing compost, and animal heat arethree ways to decrease energy costs.

Solar Greenhouses

Greenhouses can be designed to take advantageof solar radiation and cut fuel expenses. Solargreenhouses are popular with small-scalegrowers. These are super-insulatedgreenhouses designed to collect and retain solarenergy. The technology associated with solargreenhouses is rather detailed. In addition, theliterature on solar greenhouses is quite large. To

help growers identify some of the best resourceson this topic, ATTRA compiled the SolarGreenhouses Resource List.

One recent publication that features organicvegetable production in a solar greenhouse isAnna Edey’s book Solviva: How to Grow $500,000on One Acre and Peace on Earth. Solviva is Edey’saward-winning solar-powered and animal-heated greenhouse on Martha’s Vineyard. Thebook discusses greenhouse design, function,construction, and management. Ms. Edeyincludes numerous energy-efficient designs likewater walls and growtubes. She also tells howmuch everything costs, which is invaluable formarket gardeners. Solviva is available for $38from:

GFM BooksPO Box 3747Lawrence, KS 66046800-307-8949

Composting Greenhouses

Heating greenhouses with waste heat generatedby compost is a second option that takesadvantage of local resources and integratesdifferent farm activities. In a compostinggreenhouse, heat and carbon dioxide aregenerated from manure-based compostcontained in a special chamber attached to oneside of the greenhouse.

Compost-heated greenhouses gained a lot ofattention from work undertaken at The NewAlchemy Institute at Falmouth,Massachusetts. The New Alchemy Institutewas one of the premier appropriatetechnology centers that operated in the 1970sand 80s. The Institute published widely onecology, wind energy, solar energy,bioshelters, solar greenhouses, integrated pestmanagement in greenhouses, organicfarming, and sustainable agriculture.

Though the technology to implementcompost-heated greenhouses exists, they areseldom done on a commercial scale. ATTRAcan provide more information on this topic onrequest.


Animal-Heated Greenhouses

Small animals like chickens and rabbits produceheat and carbon dioxide in addition to productslike eggs and meat. A few growers have takenadvantage of this fact and integrate animalswith greenhouses as a source of heat. However,it can be a challenge to keep livestock in agreenhouse—the higher temperature andhumidity of a greenhouse are generally nothealthy for animals.

Anna Edey, mentioned above, uses an “earth-lung” to filter out the toxic ammonia gas fromthe rabbit and chicken manure she uses in herSolviva greenhouse. In addition, she keeps herchickens in a poultry room attached to thegreenhouse where temperatures do not fluctuatefrom about 70°F.

In 1996, there was a SARE-funded projectheaded by Rick Meisterheim in Michigan titled“Permaculture Greenhouse System.” He raisedchickens in the greenhouse and found that theyraised the overall temperatures inside thegreenhouse by an average of 8°F. This provedto be very helpful in raising vegetabletransplants. Rick was able to set out seedlingsmuch earlier than other years, thus increasingthe length of time his CSA generated income (5).

Again, bio-heated greenhouses hold interestamong small-scale growers who are focused onbio-integrated systems as a form of energyefficiency and biomass utilization. Of the threegreenhouse-heating methods summarized here,solar greenhouses have the least risk and holdthe most promise for commercial-scale ventures. Nevertheless, for those individuals seekinginformation on bio-heated greenhouses, ATTRAcan supply more information on request.

Organic Greenhouse Production

As defined by the USDA in 1980 (6), organicfarming is a system that excludes the use ofsynthetic fertilizers, pesticides, and growthregulators. Organic farmers rely heavily oncrop rotations, crop residues, animal manures,legumes, green manures, organic wastes, andmineral-bearing rocks to feed the soil andsupply plant nutrients. Insects, weeds, andother pests are managed by mechanicalcultivation, and cultural, biological andbiorational controls.

Organic certification emerged as a marketingtool during the 1970s and 80s to ensure foodsproduced organically met specified standards ofproduction. The Organic Foods Production Act,a section of the 1990 Farm Bill, enabled theUSDA to develop a national program ofuniversal standards, certification accreditation,and food labeling. Early in 1998, the USDA

Related publications from ATTRA include:

• Hydroponic Vegetable Production• Aquaponics: The Integration of

Hydroponics with Aquaculture• Solar Greenhouses Resource List• Organic Potting Mixes• Disease Suppressive Potting Mixes• Sources of Organic Fertilizers and

Amendments• Season Extension Techniques for Market

Gardeners• Integrated Pest Management for

Greenhouse Crops• Greenhouse IPM: Sustainable Aphid

Control• Greenhouse IPM: Sustainable Thrips

Control• Greenhouse IPM: Sustainable Whitefly

Control• Compost Teas for Plant Disease Control• Use of Baking Soda as a Fungicide• Organic Greenhouse Tomato Production• Organic Greenhouse Pepper Production• Organic Greenhouse Cucumber Production• Organic Greenhouse Lettuce Production• Organic Greenhouse Herb Production• Organic Plug and Transplant Production

No single fertilizer will provide all of theessential elements required, but acombination of organic products can bedevised.


released a draft of the new standards for publiccomment. Public opposition to these proposedstandards was vocal, sending a message to theUSDA that more work was necessary. A newdraft of organic standards may be released in2000. In the meantime, organic certification willcontinue to occur at the state level for most ofthe country. For more information on theseorganizations, ask for ATTRA’s OrganicCertifiers resource list and Organic Certificationpublication.

Growers may choose organic methods for avariety of reasons. One of the attractions ofgrowing organic produce is that it sometimesbrings a 10–30% premium in the marketplace. As organically grown produce becomes morecommonplace, however, premiums may be theexception rather than the rule, and motivationbeyond market premiums should be considered.These may include the possibility of reducedinput costs, improved farm safety, reducedenvironmental impact, and a better functioningagroecosystem.

Greenhouse technology and horticulturalpractices differ little between conventional andorganic greenhouse production. The mainvariations are concerned with pest control andfertility. The ATTRA publication Integrated PestManagement for Greenhouse Crops examines thefirst issue; the second issue is addressed in thefollowing sections.

Fertility

Although the process is more complicated, it ispossible to obtain adequate nutrients fromorganic sources, but it takes more careful andcreative management. No single fertilizer willprovide all of the essential elements required,but a combination of organic products can bedevised.

Organic fertilizers have not been wellresearched in greenhouse vegetable production.However, a 1999 study performed at theUniversity of Kentucky analyzed severalproducts for the levels of nutrients theysupplied. The researchers were attempting toprove that organic fertilizers could supplynutrients at the same level as syntheticfertilizers. Products derived from algae(Algamin, a liquid, and Maxicrop, a powder),bat guano, and fish waste (GreenAll FishEmulsion, a liquid, and Mermaid’s FishPowder) demonstrated nutrient levelscomparable to conventional, synthetic fertilizersused for greenhouse plant production (7). Thereport concluded that these organic fertilizerscould not be used as a concentrate for injectorsystems, but they would be suitable in acapillary mat subirrigation system. Forinformation on how to obtain these products,see the Resources section.

In 1993, Premier Peat Moss in Canadaconducted research on organic wastes from the

Fertilizer N-P-K Shoot wt. (grams)Crab-shell meal 8.2-1.5-0.5 18.8Blood meal 12.5-1.1-1.0 18.5Dried whey sludge 5.3-2.5-0.9 18.3Feather meal 13.6-0.3-0.2 17.3Fish meal 10.1-4.5-0.5 17.1Meat meal 7.7-3.1-0.7 16.3Cottonseed meal 6.5-1.1-1.6 16.2Fish-scale meal 10.0-3.7-0.1 15.8Distiller’s dried grains 4.3-0.9-1.1 14.5Soybean meal 7.5-0.7-2.4 14.4Wheat bran 2.9-1.4-1.3 13.5Alfalfa meal 2.5-0.3-1.9 10.8Canola meal 6.0-1.1-1.3 10.8None (control) 0-0-0 10.3


agri-food industry and their ability to fertilizegreenhouse tomato transplants (8). Theresearchers found that meal from blood,feathers, meat, crab shells, fish, cottonseed andwhey by-products increased shoot weight by57–83% over non-fertilized plants. The resultsof their study are shown on page 5.

Liquid fertilizer applied through irrigationlines—a technique known as fertigation—is acommon practice in greenhouse production. Nitrogen and phosphorus are the two primarynutrients injected through fertigation systems.Fertigation can provide supplemental doses ofthese nutrients, especially at critical periods

during the growing season such as fruit filling. However, fertigation is not a substitute for acomplete soil-based fertility program.

The injection of organic fertilizers into low-volumeirrigation systems like drip emitter and micro-sprinkler is non-conventional, because the standardmethod relies on commercial synthetic fertilizersthat are highly soluble in water. The major concernwith organics is clogging of emitters and pores withparticulate matter and algae.

In the early 1990s, researchers in Californiaconcluded that fertigation with certain organicfertilizers is feasible (9). Spray-dried fish and

Organic Strategies for Nutrient Deficiencies*Element Deficiency Symptoms RemedyNitrogen (N) Old leaves turn pale green then yellow with

reddish veins and midribs. Stunted growth.Dried blood, fish meal, or guanoextracted in water. Add greateramounts in your next compostbatch.

Phosphorus (P) Stunted growth, dull green leaves with purpletints. Old leaves scorch at the edges andwither early. Early, premature bolting.

Add reactive rock phosphate orextract of guano in solution. Addgreater amounts of guano, bonemeal, or fish meal to the nextcompost batch.

Potassium (K) Small, dark, bluish-green, glossy leaves,curving slightly backwards. Old leaves withyellow patches, scorched edges curedupwards. Small root system.

Add more kelp extract to thenutrient solution. Add greateramounts of ashes to the nextcompost batch.

Calcium (Ca) Young leaves cupped backwards, with whitespots around the edges. These later turnbrown. Forward rolling of the leaf margin.

Add lime in solution. Add greaterproportions of bone meal,gypsum, or dolomite to the nextcompost batch.

Element Deficiency Symptoms RemedyMagnesium (Mg) Leaves become bronzed, and later, yellow

patches appear between the leaf veins.Dolomite or serpentine insolution. Add greater amounts ofdolomite and animal manures tothe next compost batch.

Sulfur (S) Purpling of old leaves, which then shrivel. Young leaves small and yellow between theveins.

Sulfur in solution. Greaterproportions of gypsum andpoultry manure required in thenext compost batch.

Manganese (Mn) Veins stand out clearly with yellow inbetween. As the plant ages, small dead spotsand papery areas appear. Slow root growth.

Add extra kelp extract.

Boron (B) Split or thin misshapen roots. Roots with tornpatchy surface and dull skin.

Add extra kelp extract.

Iron (Fe) Very pale leaves, especially the youngest earlyin the season. Veins stay dark.

Add more kelp extract or placesome rusty nails in the bottom ofthe nutrient tank.

*Reprinted with permission from: Morgan, Lynette. 1997. Organic fertilizers for hydroponics. The Growing Edge. November-December. p. 32-35, 37-39.


poultry protein fertilizers were injected throughvarious drip, drip-tape, and micro-sprinklerirrigation systems, with even distribution andminimal clogging. The protein products areeasy to use because they are finely ground andsold dry. The N-P-K analysis for both fish andpoultry protein is 14-0.5-0.7. At the time of thestudy, the material cost $1.60/lb., or $12/lb. ofnitrogen. In comparison, sodium nitrate costsabout $2/lb. of nitrogen. For productinformation on spray-dried protein fertilizers,see the Resources section.

Neptune’s Harvest®, with fish, seaweed, andfish-seaweed blends, is a product line that ispopular with organic growers using dripsystems. (For more information on Neptune’sHarvest, see the Resources section.) DavidHertzell, an organic greenhouse tomato growerin Kansas, applies Neptune’s Harvest throughhis drip-tape system at 32-oz./400 gallons waterevery ten days. He and other growers prefer theblended mix to straight seaweed, because theyfeel the nutrient ratios of trace elements are notas balanced in seaweed alone. David also usesrock phosphate at 10 lbs/85’ row, as well asblood meal, bone meal, and alfalfa meal. Heuses alfalfa mulch, a heavy application of leaf-mold compost, and cover crops. He alsosolarizes his soil every five years.

In an excellent article on organic fertilizers forhydroponic systems, Dr. Lynette Morgansuggests remedies for nutrient deficiencies. Thetable on page 6 is excerpted from her article (10).

James Baker raises organic cucumbers, tomatoes,chives, and squash in Israel. He applies 20–25cubic meters (706 to 882 cubic feet) of compostper quarter acre in the first year of production,then 10 to 15 cubic meters (353 to 530 cubic feet)on following crops. In addition, he uses feathermeal for nitrogen, basalt rock for iron and traceelements, and applies bat guano through hisirrigation system. Says Baker, “I’d prefer to usepoultry manure, but that’s not strictly organicbecause the chickens are fed antibiotics andhormones, and aren’t fed organic grain” (11).

Soil vs. Soilless Culture

Greenhouse production is based on either soil orsoilless culture. In soil culture, vegetables areproduced in the native soil or in a loamy soilbrought inside the greenhouse. Soilless culture,the production of plants in a soilless medium,can be done via hydroponics or with an organic(or artificial) substrate.

The two broad categories of soilless culture areillustrated in the diagram below, with examplesof media used in each.

Soilless Culture

Organic Substrates Hydroponics

Vertical Towers Straw Bale Shallow Bed Bag Culture

Aggregate Liquid Aquaponics Bioponics

Inert Organic Mixed Nutrient Film Technique Perlite Peat Peat-Perlite Aeroponics Sand Sawdust Peat-Bark-Sand Floating Raft Gravel Bark Peat-Vermiculite Noncirculating Rockwood Rice Hulls Clay Granules


In 1974, 70 percent of U.S. production was basedon soil culture and 30 percent on soilless culture.By 1988, a significant shift to soilless systemshad occurred, with soil systems making up only40 percent of the acreage (12). The majority oflarge producers in Canada raise tomatoes,cucumbers, and peppers in rockwool, andlettuce is usually raised with a nutrient filmtechnique (NFT) system (3). Bag culture is oftenpracticed in the U.S., however. The chiefreasons soilless culture became so popular are:a) the elimination of fumigation and steamtreatments for soil-borne diseases; b) ease ofinstallation; c) technical assistance available forsoilless systems; and d) fertility control throughcommercial soluble fertilizers.

Five greenhouse production methods suitablefor organic production are covered in thefollowing material: soil culture, bag culture,vertical towers, straw bale culture and shallowbed culture. Although an overview ofhydroponics is discussed in this publication, seeATTRA’s Hydroponic Vegetable Production formore in-depth information.

Soil Culture

In soil culture, also known as ground culture,vegetables are raised on level ground as well asin mounded beds. Soil culture is more popularwith organic growers than hydroponic methods.One of the reasons organic growers prefer soilculture to hydroponics is that soil-buildingpractices are an already familiar concept basedon decades of research and experience.

Production techniques used in ground cultureare similar to intensive market gardeningmethods used in the field. Rear-tine tillers ormechanical spaders are used in soil preparation,and specialized wheel hoes and hand tools areused for cultivation and weed control. Organicfertilizers and soil amendments are extensivelyused to feed the soil.

In Quebec, organic farmers raising greenhousetomatoes by the ground culture method use tworows per bed raised about one foot high. Compost is applied at a rate of 1.2 to 2.4 cubicyards per 1000 sq. feet. The first year it is

applied 5–6 times per growing season at 5–6week intervals. In years two through four thecompost is applied at a lower rate. Followingcompost application, the beds are covered withstraw mulch. Soil organic matter in thesegreenhouses ranges from 10–12% up to 25–30%.

In contrast, the Luebkes, one of the best knownorganic farming families in Austria, fertilizegreenhouse tomatoes at a rate of 8tons/acre/year (13). However, they useControlled Microbial Compost™—a highquality, microbially inoculated compostprepared under aerobic (oxygen-present)conditions. In addition to compost, greenmanures are an integral part of the Luebke soilmanagement program. After the green manureis mowed but prior to plowdown, the greenresidue is sprayed with a microbial inoculant tospeed decomposition and enhance humusformation. Soils treated in this manner havetested at 15% organic matter. More informationon CMC compost is available from ATTRA onrequest.

ATTRA publications that explain sustainablefertility management in more detail includeSustainable Soil Management, Non-ConventionalSoil Amendments and Farm-Scale CompostingResource List.

Cover Cropping in Ground Culture Systems

Cover crops fit nicely into ground culturesystems that include a crop-free rest period (insummer, for example). Short-term cover cropsinclude legumes, buckwheat, annual ryegrass,oats, rapeseed, and oilseed radish. Often, thechoice of cover crop will depend on thevegetable rotation and the intended purpose. Cover crops can replenish and help buildorganic matter in soils, increase microbialactivity, add nitrogen, and help prevent orsuppress diseases and nematodes, especiallywhen brassica and oilseed radish cover cropsare used.

Marty Legant, who raises 2 acres of organicwinter tomatoes by the ground culture methodin Parowan, Utah, has an 8-week period inwhich cover crops occupy his greenhouse. He’s


raised buckwheat and oats in the past, and hasplans to try hairy vetch. At plowdown, heinoculates the green manure with vitamin B-12,sugar, and a catalyst to help speeddecomposition and enhance humus formation.

Anna Edey, whose primary commercial cropis salad greens, recommends the following(14).

For average soil, add, per squareyard: 4 gallons of compost, 4 cubicfeet of peat moss, 1-2 pounds ofsoft rock phosphate, 1-2 pounds ofgreensand, and lime if needed. Spread it out evenly and blendthoroughly by rototilling twice,rake it smooth and level, and thenwater well enough to soak throughto the full depth.

The next day sow buckwheatseed, spaced ¼ to ½ inch apart,cover lightly and water it well. Let the buckwheat grow forabout two to three weeks, toabout 10-12 inches high, thenturn it under and sow anotherround of buckwheat. Repeatthese buckwheat cycles until thegrowing beds in the greenhouseare ready to be filled.

In order to maintain highest soilfertility, the soil needs to beenriched with compost andminerals four to five times peryear. I recommend that everyarea of the greenhouse…receivea buckwheat treatment once ayear.

An alternative to growing cover crops inside thegreenhouse is incorporation of freshly choppedcover crops or pasture-grown foragestransported from a nearby field. These arecalled green-leaf manures.

Weed Control in Ground Culture Systems

Strategies for non-herbicidal weed controlinside the greenhouse include a combination of

hand hoeing, mechanical cultivation, steampasteurization, soil solarization, mulching(fabric, plastic, or organic mulches), and poultrygrazing.

Poultry grazing is a unique method of“biological” weed control that may be an optionfor some greenhouse growers. This system isused by Lynn Shanks, a vegetable grower nearBixby, Oklahoma (15). Mr. Shanks raisesgreenhouse tomatoes and early-seasoncantaloupes by the ground culture method. Tomanage weeds, he houses jungle fowl fromIndia in the greenhouse to “graze” on weeds. The jungle fowl are also deft at picking insectsoff the vegetable plants without damaging anyfruits. (Jungle fowl should not be confused withthe domesticated chicken, which is notorious forpecking at tomatoes in the garden). Theimpressive aspect of this system is that weedingrequires no labor, mulching, or cultivation onthe part of Shanks’ family.

Soil Disinfection in Ground Culture Systems

A major concern in ground culture systems issoil sterilization or pasteurization for control ofsoil-borne pathogens. Methods ofdisinfection—including solarization, steam,electrical heat, and biological control—arecovered in the ATTRA publication titledIntegrated Pest Management for Greenhouse Crops.

Resources on Ground Culture Systems

The New Organic Grower, a 340-page book byEliot Coleman, is one of the best resources onintensive market gardening. Many of thetechniques he describes—especially fertility,weed control, and soil blocking—are readilyadaptable to greenhouse ground culture. Coleman has also written two books dealingwith year-round production of food. The first isFour-Season Harvest, which focuses on usingcold frames and high tunnels. The second is TheWinter Harvest Manual: Farming the Back Side ofthe Calendar. This small book concentrates oncommercial winter production of freshvegetables in cold climates withoutsupplementary heat. See the Resources sectionfor more information.


Soilless Culture

Soilless culture methods usually have higheryields than ground culture systems. Anotheradvantage of a soilless system is easier controlof disease problems. In the soilless techniquesdescribed below, the media can be disposed ofafter one crop has been grown, or it can bepasteurized relatively easily.

Bag Culture

In bag culture, plants are grown in a soillessmedium contained in lay-flat or uprightpolyethylene bags (2–5 gallons in size) and fedwith liquid fertilizers through drip irrigationlines. Media can be peat/vermiculite, sawdust,rockwool, rice hulls, pine bark, peanut hulls, ormixes of any of those. Bag culture is adaptableto both aggregate hydroponics fed with liquidfertilizers as well as standard soilless culture, inwhich the bulk of fertility is supplied viacompost-based potting mixes.

Upright bags should be purchased atgreenhouse supply houses, since householdgarbage bags are usually not strong enough. Upright bags usually contain one plant per bag.Lay-flat bags are closed and are made of 4-mil,UV-protected polyethylene. Lay-flat bags oftenhave two or three plants per bag. Bags are mostoften placed in double rows in the greenhouse.

Bag culture is well suited to the production ofupright and vining crops like tomatoes,cucumbers, and peppers. Bag culture hasbecome the preferred method of greenhousevegetable production in many parts of the U.S.because it is easy to establish and managesuccessfully. One problem with bag culture isthe potential for excess fertilizer solution toleach out of the drainage holes in the bags andinto the greenhouse soil.

Adapting bag culture to standard soillessproduction in a certified organic greenhouseoperation requires specially formulated organicpotting mixes. An organic potting mix shouldnot include any synthetic fertilizers or wettingagents. Growers can purchase certified organicpotting mixes from a commercial supplier, ormix their own. Organic bag cultured vegetablesmay include a combination of incorporated,topdressed, liquid-fed, and foliar-fedfertilization systems. See ATTRA’s OrganicPotting Mixes publication for a summary ofmedia and fertilizers that can be used in organicproduction systems; this publication includesrecipes for organic potting mixes collected fromthe alternative agriculture literature andinterviews with organic farmers.

Adapting bag culture to soluble hydroponics orbioponics requires special hydroponic formulasand ingredients. These are covered inATTRA’s Hydroponic Vegetable Productionpublication.

Vertical Towers

A form of bag culture is the vertical tower. Long bags full of media are hung fromsupport wires or beams, and plants are placedin slits or holes made on the sides of the bag.The appeal of this system is the very efficientuse of greenhouse space; since the plants areusing vertical space, very little floor space isneeded.

The most popular vertical tower is a patentedsystem called Verti-Gro. Verti-Gro uses square,styrofoam pots, which are stacked 8–10 potshigh and can be re-used for 5–10 years. TimCarpenter, who owns the company,recommends using perlite and coir (coconutfiber) for media. Fertilizer is supplied by a dripirrigation system, in which solution flows fromthe topmost to the bottom box and into a gravelsupport base, where it can be captured and re-used. Crops that have been grown with thissystem include lettuces, strawberries, herbs,tomatoes, greens, spinach, nasturtium, and cutflowers. For more information on this system,contact:

Bag culture has become the preferredmethod of greenhouse vegetable productionin many parts of the U.S. because it is easyto establish and manage successfully.


Verti-Gro, Inc.720 Griffin Rd.Lady Lake, FL 32159800-955-6757352-750-4202http://vertigro.com

Straw Bale Culture

Straw bale culture was an important method ofgreenhouse cucumber production in Europe andCanada prior to the development of rockwooland NFT hydroponics. Bale culture can be

especially useful as a method to avoid soilscontaminated with diseases or in greenhouseswith concrete or gravel floors. Based on limitedexperience in Canada in adapting straw baleculture to organics, this method appears to havemerit where one of the aforementionedconditions exists.

In bale culture, the greenhouse floor can beconcrete or lined with plastic or fabric mulch,and bales are laid out in rows. Bales are pre-wetted with manure tea, which initiatesdecomposition and causes the bales to heat up. On the average, about 7 gallons of water arerequired for a normal 50 lb. bale. When thetemperature of the bales cools down to below110° F, they are capped with six inches of acompost-based potting mix to accommodatethe root balls of the transplants. Normally,planting would take place on about theeleventh day.

Fertilizers topdressed to the bales include drybone meal, sul-po-mag, and an organic nitrogensource. Manure tea, seaweed, and fish-seaweedblends are used as liquid fertilizers. As thebales continue to ferment and decompose, heatand carbon dioxide are generated and these

byproducts promote plant growth by warmingthe roots and enriching the greenhouseatmosphere.

In considering straw bale culture, the cost of thebales and topcapping compared with costs of acomparable production system such as bagculture, will need to be weighed. Also, inorganic culture, a major factor would be theavailability of certified organic straw. Herbicideresidues in straw can cause serious injury togreenhouse crops.

Canadian studies conducted in the 1960s and1970s showed that:

• Spring-grown cucumbers grown on strawbales yielded an average of 21% more fruitthan soil-grown plants, although fall-sownplants did not have a yield increase.

• Wheat straw bales provided the best results,followed by clover straw. Timothy/alfalfahay bales gave poor results.

• Using half a bale per plant caused nosignificant loss in yield.

• Using a plastic sheet under the bales causeda 9% reduction in yield

• There is little or no difference in yieldbetween bales placed on the soil surface andthose buried or half-buried in a trench.

• Growing in straw bales was economicallyfeasible for spring-sown plants (16).

Missouri farmer Eric Hemple raises organicarugula, squash, green beans, onions,eggplant, tomatoes, and cucumbers using thestraw bale method. A neighbor providesorganic straw bales at a price of $3 each. Hemple places the bales between two sheets ofcorrugated tin braced with stakes to create amore uniform growing surface. He uses asterile potting mix as his capping medium andbone meal, blood meal, fish emulsion, androck phosphate as his fertilizers. Hemple usesa drip irrigation system and warns that carefulattention to watering is essential, as are propernutrient levels. He sells all his products atretail and estimates that he is receiving a grossreturn of 50 cents per square foot of bale spaceper week (17).

In considering straw bale culture, thecost of the bales and topcappingcompared with costs of a comparableproduction system such as bag culture,will need to be weighed.


Shallow Bed Culture

Shallow bed culture, also known as thin layerculture, is the production of sprouts orherbaceous herbs and vegetables in a thinlayer—1 to 3 inches in depth—of potting mixor compost laid on top of plastic mulch orwoven weed barrier. Herbaceous cropsadapted to shallow bed culture includespecialty lettuces, greens, cresses, and selectedculinary herbs.

At least one commercial sprout grower inCalifornia uses this method in the production oforganic wheat grass, sunflower, and buckwheatsprouts. Root-zone heating tubes are laidunderneath the plastic to provide bottom heat. In turn, they rest on top of polystyrene panelslaid directly over the greenhouse soil. Gas-firedwater heaters are used to heat the water, butsuch a system could easily be retrofitted to solarcollectors located outside the greenhouse. Narrow boards are laid out every three feet towalk up and down between the beds to seed,water, and harvest.

Jay Fulbright, a commercial lettuce and specialtygreens grower in Arkansas, has three growingsystems. In the first, he amends his soil withcompost and pelletized chicken litter and plantsdirectly into the ground. In the second system,he uses tables made of 2x8 lumber and places3½” of compost onto 2x4 welded wire mesh,covered with perforated plastic to allow fordrainage. All the greens are hand-harvestedusing this system. The third method involvesplacing 4” of compost and chicken litter directlyonto polypropylene sheets laid on the ground. Jay devised the third method in order to cutdown on labor; he hopes to be able to use asalad harvester. He is now harvesting anaverage of 300 pounds of lettuce per week,which he sells to restaurants and specialtygroceries.

Education Concerns for Hunger Organization(ECHO), a nonprofit organization that works inagriculture development, is promoting theshallow bed method as a technique for rooftopgardening in urban settings. The beds theydescribe are deeper—3 to 6 inches in depth—

and are more typical of standard trough cultureusing a soilless mix. They’ve achieved goodsuccess raising a variety of vegetable cropsusing locally available materials such as leafmold and compost.

ECHO has published several reports on shallowbed culture and low-tech hydroponics. For moreinformation, see their web site athttp://www.echonet.org/azillus/azch17ov.htmor contact them at:

Educational Concerns for HungerOrganization (ECHO)17391 Durrance Rd.North Ft. Myers, FL 33917941-543-3246http://www.echonet.org

Hydroponics

In hydroponics, plants are grown in a soillessmedium and fed with fertilizer nutrientsdissolved in solution. There are two broadcategories of hydroponics: liquid hydroponicsand aggregate hydroponics.

Liquid systems feature the nutrient filmtechnique (NFT), aeroponics, floating raft, andnoncirculating water culture. Aggregate systemsinclude inert, organic, and mixed mediacontained in bag, trough, trench, and benchsetups.

Liquid systems like NFT are often managed asclosed, or recirculating systems. Aggregatesystems are commonly managed as open, orflood and drain fertigation systems.

There are three basic approaches to organichydroponic vegetable production: a) solubleorganics, also known as hydro-organics, b)integration of hydroponics with aquaculture, alsoknown as aquaponics, and c) bioponics.

Hydro-organics is based on hydroponic solutionsderived from organic fertilizers like fish meal,spray-dried blood, and guano. Aquaponics isbased on recirculating aquaculture in whichirrigation effluent from fish tanks is used tofertigate sand or gravel cultured hydroponic


vegetables. For more information, see theATTRA publication Aquaponics. Bioponics, or“living hydroponics,” is based on inoculating thehydroponic medium with microorganisms. SeeATTRA’s Hydroponic Vegetable Production formore information on bioponics.

The key difference between organic and chemicalhydroponics is the source of fertility and presenceof microorganisms. Microbes are essential toorganic systems because they help regulate pHand availability of nutrients. In addition,bioponic researchers claim that enzymesproduced by the microbes interact with plantroots and stimulate biochemical processes in theplants which enhance the flavor of bioponicproduce. For more information on hydroponics,see ATTRA’s publication Hydroponic VegetableProduction.

Variety Selection

Variety or cultivar selection plays an importantrole in greenhouse vegetable production. Cultivars often originate in greenhousebreeding programs where selection is based ondisease resistance and ability to perform undergreenhouse climatic conditions. Greenhouseseed vendors and the Cooperative ExtensionService can recommend appropriate cultivars. Seed suppliers are listed in the Resourcessection below. See the ATTRA series ofpublications on specific greenhouse crops forother recommendations.

Economics of Greenhouse VegetableProduction

Greenhouses are expensive to build and operate.A commercial greenhouse (30’ x 100’) withcomplete heating, cooling, and ventilationsystems will cost between $10,000 to $30,000 toerect and equip.

Low cost greenhouses—like hoop houses andattached solar greenhouses—can be constructed

for as little as $500 to $1,500. Hoop houses aresimilar to plastic Quonset greenhouses but arenot equipped to heat or cool, and are usedprimarily for season extension. Solargreenhouses work fine for small-scaleproduction—especially for the production oftransplants and cool-season lettuces—but maynot provide adequate space or climate controlfor commercial tomato, cucumber, or pepperproduction.

Otto Wells, a professor at the University of NewHampshire, found that growing tomatoes in anunheated 14x96-foot hoop house in NewHampshire could be profitable, if he realized ayield of 2000 pounds and sold the tomatoes for$1.60/lb. Using these estimates, the growerwould earn a net return of 71 cents per pound(18).

The greenhouse vegetable business iscompetitive. Wholesale markets for off-seasonproduce often become saturated and causeproduce prices to drop. Competition stemsfrom an established domestic industry as well asDutch imports. In addition, field-grownMexican produce frequently sells at half theprice of greenhouse produce. Local andspecialty markets provide alternative outlets,but the volume of produce that can be moved ismuch less than what can be shipped to distantmarkets.

Greenhouse vegetable yields determinepotential gross sales. Typical yields ofgreenhouse tomatoes are 20 to 30 lbs. per vine,or 2–3 lbs. per square foot. Greenhousecucumbers yield around 2 dozen fruits per vine.Greenhouse peppers yield 2½ -3 lbs./sq. ft. Astudy conducted in Missouri in the winter of1995–96 showed that supplemental lighting oftomatoes increased total yields from 12,444 kg to18,840 kg. Because the lighted tomatoes werelarger, they brought a better price and resultedin additional revenues of $25,000 (19).

Prior to sinking lots of money into a greenhouseventure, growers should examine produceprices in their region and estimate their cost ofproduction. Historically, the breakeven pricefor most greenhouse tomatoes has been around

The greenhouse vegetable business iscompetitive.


75 cents per pound, with selling prices rangingfrom 90 cents to $1.60 per pound. The break-even price for cucumbers is similar—around 75cents per pound (18-21).

Estimates of net income from conventionalgreenhouse tomatoes range from $3,100 to$18,500 per greenhouse unit (21, 23). Theseestimates are for good yields and favorablemarket conditions. Low yields, or a dip in themarket, can lead to negative returns to thegrower.

The following estimates from 1994 areassociated with a double polyethylenegreenhouse: the greenhouse itself would costabout $6–$7 per square foot; hydroponicequipment would be an additional $1.50–$2.00per square foot; land cost, site preparation,foundations, concrete floors, and utilitieswould be an extra $3.50–$4.00 per square foot(24).

As a suggestion, growers should gather all theeconomic data they can about the greenhousevegetable business before building agreenhouse. Also, take a look at othergreenhouse business enterprises and determineif vegetables are really the best deal. As anexample, greenhouse vegetable growers in someparts of the country have begun to diversify intobedding plants because that market is morelucrative.

Developments in the Greenhouse Industry inthe Last Decade

One exciting development is the introduction ofbumblebees for greenhouse tomato pollination.

Pollinating by hand is expensive (in terms oflabor), tedious, and time-consuming. Severalcompanies are now raising bumblebees to beused for indoor pollination. Although the hivesare expensive, they pay for themselves manytimes over.

There have also been many new biorationalpesticides in the last five years. Some of thesebiorational pesticides (also known as least-toxic, environmentally friendly, orbiopesticides) include Bt, Beauveria bassiana,and Cinnamite™, which was just released in1999 for control of several greenhouse pests.

Use of biological control agents has alsoincreased in the last decade. Much more isknown about how to use these insects to theirfullest advantage and about how to applyinsecticides while preserving predators. Formore information on these, see the ATTRApublication Integrated Pest Management forGreenhouse Crops.

Additionally, new cultivars bred exclusively forgreenhouse growing are now available to smallgrowers. Seed vendors like DeRuiter's areconstantly testing new cultivars for greenhouseproduction. Although seed for greenhousecrops is still more expensive than for field crops,it has become more affordable. Growersthemselves have been testing cultivars forsuitability in greenhouse work, especially in thearea of heirloom vegetables.

Another change that is occurring is in the fieldof greenhouse coverings. Modern greenhouseplastics are resistant to breakdown fromultraviolet light and are rated to last severalyears. This reduces annual expenses formaterials, labor to reglaze, and fees for landfilldisposal. Structured sheets are the deluxealternative to Quonset-style plastic houses. They are more expensive to purchase andinstall, but they provide optimumenvironmental controls and have a very longlife. Research into the chemistry associatedwith greenhouse glazing is aimed at energysavings, pest control, and enhancement of plantgrowth.

Eliot Coleman and his wife BarbaraDamrosch raise organic produce in theirgreenhouses in Maine. They charge$6.25/lb for salad mix, $3.00/lb. for bulkspinach, $1.25-$2.00 for carrots, and$3.00/lb for baby turnips. They droppedscallions because they couldn’t makemoney from them (22).


Summary

Organic greenhouse vegetable production haspotential as a niche market for out-of-seasonproduce and as a sustainable method ofproduction. Soil-based systems are readilyadaptable to certified organic production, butspecial care must be taken for soil-borne diseasecontrol. Soilless systems can also be adapted toorganic culture, and systems like bag culture areeasy to get into. Little research is available forspecific organic production systems, pottingmixes, and fertilizer regimens, however, andgrowers must use best available knowledge andimprovise.

References:

1) Snyder, Richard G. 1993. The U.S.greenhouse vegetable industry update andgreenhouse vegetables in Mississippi. p. 78–82. Proceedings of the American GreenhouseVegetable Growers Conference. Held Aug.19–21, Denver, CO.

2) Census of Agriculture. 1997. U.S. Census ofHorticulture Specialties. Bureau of theCensus, U.S. Department of Commerce,Washington, D.C.

3) Anon. 1999. Agriculture and Agri-FoodCanada: Introduction to the GreenhouseVegetable Industry. Greenhouse &Processing Crops Research Centre, Ontario,Canada. http://res.agr.ca/harrow/hrcghar.htm. 16 p.

4) Jones, J. Benton, Jr. 1999. Tomato PlantCulture. CRC Press, Boca Raton, FL. p. 90.

5) Meisterheim, Rick. 1998. SARE grant project— final report. Project No. FNC 96–139. 4 p.

6) USDA Study Team on Organic Farming. 1980. Report and Recommendations onOrganic Farming. USDA, Washington, DC. 94 p.

7) Anderson, Robert G. and Robert Hadad. 1999. Nutrient analysis of organic fertilizersfor greenhouse vegetable production. HortScience. June. p. 463. Abstract.

8) Gagnon, Bernard and Sylvain Berrouard. 1994. Effects of several organic fertilizers ongrowth of greenhouse tomato transplants. Canadian Journal of Plant Science. January. p. 167–168.

9) Schwankl, Lawrence J., and Glenn McGourty. 1992. Organic fertilizers can be injectedthrough low-volume irrigation systems. California Agriculture. September–October. p. 21-23.

10) Morgan, Lynette. 1997. Organic fertilizersfor hydroponics. The Growing Edge. November–December. p. 32–35, 37–39.

11) McMullin, Eric and Warren Clark. 1993. Riding Israel’s vegetable boom. AmericanVegetable Grower. March. p. 34–35.

12) Hickman, Gary. 1988. Greenhouse vegetableproduction in the United States—1899–1988—A statistical review. p. 6-8. In: Proceedings ofthe American Greenhouse Vegetable Growersconference. Held Sept. 6–9, Orlando, FL.

13) Uta Luebke. 1994. Humus ManagementSeminar. Bird-in-Hand Village, PA.

14) Edey, Anna. 1998. Solviva: How to Grow$500,000 on One Acre and Peace on Earth. Trailblazer Press, Martha’s Vineyard, MA. 221 p.

15) Lynn Shanks. 1994. Oklahoma StateUniversity Field Day, Bixby, OK.

16) Loughton, Arthur. 1977. Straw-bale cultureof greenhouse crops. p. 208–215. In: MerleH. Jensen (ed.) Proceedings of theInternational Symposium on Controlled-Environment Agriculture. Held April 7–8,1977, Tucson, AZ.

17) Flaim, John. 1999. Growing in haybales. Small Farm Today. August. p. 58–60.

18) Byczynski, Lynn. 1993. Greenhouse tomatoconsiderations. Growing for Market. April. p. 1, 12.

19) Larson, Arley, Alex Ching, and Scott Walk. 1996. Economics of greenhouse tomatoproduction in the rural north central U.S. ActaHorticulturae. No. 429. p. 75–80.


20) Schatzer, Raymond Joe, B. Dean McCraw,Ahmed Al-Abdulkador and Harry P. Mapp. 1994. The Economics of Bag CultureGreenhouse Tomatoes in Oklahoma. CurrentFarm Economics. December. p. 29–40.

21) Al-Abdulkador, Ahmed M. 1992. EconomicFeasibility of Greenhouse VegetableProduction in Oklahoma. Oklahoma StateUniversity, Stillwater. M.S. Thesis. 139 p.

22) English, Jean. 1999. Seasoned farmersspread the word about year-round growing. Maine Organic Farmer & Gardener. June-August. p. 20–23.

23) Hochmuth, George J. 1992. Production andeconomics of rockwool tomatoes in Florida. p. 40–46. In: Proceedings of the 13th AnnualConference on Hydroponics. HydroponicSociety of America, Concord, CA.

24) Anon. 1998. Greenhouse cucumbers. http://www.orst.edu/Dept/NWREC/cuc-gh.html. 6 p.

Greenhouse Vegetable Seed Sources:

Crop King5050 Greenwich Rd.Seville, OH 44273800-321-5656http://www.cropking.com/

Sell treated seed only.

De Ruiter Seeds, Inc.3001 Bethel Rd., Suite 118Columbus, OH 43220614-459-1498http://www.deruiterusa.com/

Can special-order untreated seed.

Hydro-Gardens, Inc.P.O. Box 25845Colorado Springs, CO 80936888-693-0578http://www.hydro-gardens.com/

Sell untreated and treated seed.

Petoseed Co., Inc.1905 Lirio Ave.Saticoy, CA 93004805-647-7386

Sell untreated and treated seed.

Stokes Seeds, Inc.P.O. Box 548Buffalo, NY 14240800-396-9238http://www.vaxxine.com/seeds/seedpage.htm

Sell some untreated seed.

Suppliers of Organic Fertilizers:

(For a complete listing of suppliers of organicfertilizers, see ATTRA’s publication Sources forOrganic Fertilizers & Amendments.)

AlgaminPeaceful Valley Farm SupplyPO Box 2209Grass Valley, CA 95945888-784-1722

GreenAll Fish EmulsionPeaceful Valley Farm Supply (see addressabove)

Neptune’s HarvestNeptune’s Harvest Fertilizer88 Commercial StreetGloucester, MA 01930800-259-4769

MaxicropMaxicrop International, Inc.[Contact: Per Ohrstrom]PO Box 964Arlington Heights, IL 60006800-535-7964

Mermaid’s Fish PowderPeaceful Valley Farm Supply (see addressabove)

Spray-dried protein fertilizersCalifornia Spray Dry Co.P.O. Box 5035Stockton, CA 95205209-948-0209

Resources:

Books:

Coleman, Eliot. 1992. Four Season Harvest. ChelseaGreen, Post Mills, VT. 212 p.

Inspired by Scott and Helen Nearing's garden inthe late '60's and based on the author's success withharvesting fresh vegetables year-round in New England,this book contains details on design, construction, andmanagement of the outdoor garden, cold frames, tunnels,


and root cellars. It includes growing tips for 50 vegetablecrops, a planting schedule for extended harvests for alllocations in the US, and sources of tools and supplies.Available for 19.95 from:

Chelsea Green PublishingP.O. Box 513Lebanon, NH 03766 800-639-4099

Coleman, Eliot. 1995. The New Organic Grower: AMaster's Manual of Tools and Techniques for theHome and Market Gardener, 2nd Ed. Chelsea Green,White River Junction, VT. 340 p.

Written primarily for the market gardener with 1to 5 acres, the book is based on over 25 years of study andpersonal experience. It covers everything from landselection to marketing, including soil fertility management,field layout and spacing, rotations, direct seeding,transplanting, cultivation, season extension, andintegration of livestock into the vegetable system. Extensivechapter notes and annotated bibliography. Available for$24.95 from Chelsea Green (see address above).

Coleman, Eliot and Barbara Damrosch. 1998. TheWinter Harvest Manual. Four Season Farm,Harborside, ME. 56 p.

Emphasis is on commercial production ofgreenhouse vegetables. Available for $15 from:

Four Season FarmRR Box 14Harborside, ME 04642

Grotzke, Heinz. 1990. Biodynamic GreenhouseManagement. Biodynamic Farming and GardeningAssociation, Kimberton, PA. 112 p.

One of the few publications specific to organicgreenhousing. Grotzke has chapters on soils, fertilization,and biodynamic preparations, but they are short ontechnique and mostly contain insights on the biodynamicview of greenhousing. He states that soilless culturesystems lack essential microorganism activity andtherefore only soil-based potting mixes or ground culturesystems can produce biodynamic quality produce. Available for $12 from:

Fertile Ground BooksPO Box 2008Davis, CA 95617800-540-0170http://www.agaccess.com/

Twenty-one separate fact sheets comprise the 137-page Greenhouse Vegetable Guide, which treats topicsranging from locating and constructing thegreenhouse to insects and diseases attackinggreenhouse vegetables. Included is an 18-page factsheet on production economics, marketing, and

financing of greenhouse vegetables. It is available for$10.00; make checks payable to TAEX. Contact:

Greenhouse PublicationsRoom 225 HFSBTexas A&M UniversityCollege Station, TX 77843-2134

Hydro-Gardens, Inc. in Colorado Springs, Colorado,carries a large selection of publications ongreenhouse vegetable production. See their web sitefor a complete listing. Contact: Hydro-Gardens, Inc.

P.O. Box 25845Colorado Springs, CO 80936888-693-0578http://www.hydro-gardens.com/

Selected Publications available from Hydro-Gardens,Inc.

Florida Greenhouse Vegetable Production Handbook. $19.95

Greenhouse Tomatoes, Lettuce & Cucumbers, by S.H.Wittwer and S. Honma. $17.95

Nutritional Diseases in Glasshouse Tomatoes,Cucumbers, and Lettuce, by Roorda van Eysinga andK.W. Smilde. $53

Vertical Plant Production Manual. $35

Greenhouse Tomato Instructional & Plant CultureManual. $10

Growing Greenhouse Tomatoes in Soil and in SoillessMedia. Available only on the Internet.

Soilless Culture of Commercial GreenhouseTomatoes. $3

Greenhouse Cucumber Instructional and PlantCulture Manual. $10

Growing Greenhouse Cucumbers in Soil and inSoilless Media. Available only on the Internet.

Cucumber Diseases, by W.R. Jarvis and V.W. Nuttall. $5

The Cultivation of European Cucumbers inGreenhouses. By Nunhems Seed Company, Holland.$5

Greenhouse Pepper Pamphlet. $2


Periodicals:

The Growing Edge is a bi-monthly magazine thatfocuses on hydroponics and high-tech gardeningfrom an ecological angle. The emphasis is ongreenhouses, hydroponics, artificial lighting, dripirrigation, and other protected culture methods. Special issues have featured articles on bioponics andorganic soilless culture. Back issues are available. Contact:

The Growing Edge New Moon Publishing

341 SW 2nd Street Corvallis, OR 97333 800-888-6785

http://www.growingedge.com/$26.95/year

Trade Publications:

The trade journals listed below regularly reviewgreenhouse developments and products. The buyer's guideissues are a comprehensive source of supplies.

Greenhouse GrowerMeister Publishing Company37733 Euclid Ave.Willoughby, OH 44094440-942-2000440-942-0662 Faxhttp://www.greenhousegrower.com

$29/year for 12 issues; Buyer’s Guide issue everysummer

GMPro (Greenhouse Management & Production)Branch-Smith PublishingPO Box 1868Fort Worth, TX 76101800-434-6776817-882-4120817-882-4121 Faxhttp://www.greenbeam.com

12 issues/year; free to qualified greenhousegrowers; $96/year for non-growers

Greenhouse Product NewsScranton Gillette Communications, Inc.380 E. Northwest Hwy.Des Plaines, IL 60016-2282847-298-6622847-390-0408 Faxhttp://www.greenhouseproductnews.com

$30/year for 12 issues

GrowerTalksBall Publishing Co.P.O. Box 9335 N. River StreetBatavia, IL 60510-0009630-208-9080630-208-9350 Faxhttp://www.growertalks.com

$25/year for 14 issues

American Vegetable GrowerMeister Publishing Co.37733 Euclid AvenueWilloughby, OH 44094440-942-2000440-942-0662 Faxhttp://www.greenhousegrower.com

$15.95/yr, 12 issues. Buyer's Guide published inJuly issue.

Web Sites:

http://www.ces.ncsu/edu/depts/hort/hil/hil-32-a. htmlGreenhouse Vegetable List of References

http://www.cahe.nmsu.edu/pubs/_circulars/circ556. htmlGreenhouse Vegetable ProductionNew Mexico State University

An excellent overview of greenhouse vegetableproduction. The circular includes information onSite Selection, Greenhouse Design, GreenhouseCoverings, Environment, Soil Culture,Hydroponic Culture, Carbon Dioxide, IPM, andDisease. The circular is specific to tomato,cucumber, and lettuce production.

http://aggie-horticulture.tamu.edu/greenhouse/ghhdbk/handbook. htmlhttp://aggie-horticulture.tamu.edu/greenhouse/guides/green/green. htmlTexas Greenhouse Management HandbookTexas A&M University, Aggie Horticulture

Comprehensive information on GreenhouseStructures, Greenhouse Heating Requirements,Growing Media, Growing Media & pH, FertilizingGreenhouse Crops, Calculating Parts Per Million,Diagnosing Nutritional Deficiencies, IrrigatingGreenhouse Crops, Monitoring the Quality ofIrrigation Water, Treating Irrigation Water,Managing Soluble Salts, Air, Water andMedia...Putting Them All Together, and AdditionalReferences for Greenhouse Management.


http://ext.msstate.edu/pubs/pub1957.htmStarting A Greenhouse BusinessMississippi State University, Cooperative ExtensionService

This information sheet provides an overview offactors to be considered by the greenhouse business.The cost estimates used are intended forinformational purposes only, since costs varydepending on the supplier and crop mix selected.

http://www.greenhouse-bbs.comGreenhouse Industry Trade Show On-Line

Online resource to greenhouse growers, suppliers,buyers, and researchers.

http://www.ext.vt.edu/departments/commhort/ commhort-30.htmlUpdate on Production Costs/Expected ReturnsBudget for GreenhouseVirginia Cooperative Extension

http://www.cals.cornell.edu/dept/flori/tcwres1.htmlControlled Environment Agriculture InformationResources 1996Cornell University College of Agriculture and LifeSciences

An online resource listing of publications (books& journals) on the following topics: Conferences,Trade Journals, Newsletters, IndustryOrganizations, Greenhouse Suppliers, DiagnosticServices, Business Planning & Operation,Cropping Systems, Greenhouse Management,Photosynthesis Management, Greenhouse CropProduction, General Crop Production, PostHarvest Horticulture, and Interiorscaping.

By Lane Greer and Steve DiverNCAT Agriculture Specialists

January, 2000

The electronic version of OrganicGreenhouse Vegetable Productionis located at:http://www.attra.org/attra-pub/ghveg.html

The ATTRA Project is operated by the National Center for Appropriate Technology under a grant from theRural Business-Cooperative Service, U.S. Department of Agriculture. These organizations do not recommend orendorse products, companies, or individuals. ATTRA is located in the Ozark Mountains at the University ofArkansas in Fayetteville at P.O. Box 3657, Fayetteville, AR 72702. ATTRA staff members prefer to receiverequests for information about sustainable agriculture via the toll-free number 800-346-9140.

http://www.cals.cornell.edu/dept/flori/tcwres1.html#10

Organic Greenhouse Vegetable Production - CiteSeerX

Documents

Transcript of Organic Greenhouse Vegetable Production - CiteSeerX