Realizing the potential of high tunnel tomato production and income in southern New England

Final Report for ONE13-191

Project Type: Partnership
Funds awarded in 2013: $14,996.00
Projected End Date: 12/31/2013
Region: Northeast
State: Rhode Island
Project Leader:
Andy Radin
University of Rhode Island
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Project Information


A high-tunnel trial of 13 tomato varieties and a production practice demonstration was carried out during the 2013 growing season at the University of Rhode Island and on the farms of three participating growers.  Per-plant yields and tissue nutrient levels were measured at the university trial, and grower-participants kept track of overall performance and customer receptivity with these varieties. Rhode Island growers attended several meetings concerning techniques used, which included a viewing of the project itself. All who attended were impressed by the overall health of the plants under the management system that included “lean and lower” trellising, fertigation with organic amendments, and the performances of the various varieties.  Use of intensive techniques such as fertigation, leaning and lowering, and selecting varieties appropriate for this environment, can result in high revenue on small land area.  In this case, it is possible to grow over $30,000 of tomatoes on one sixteenth of an acre.

Overall favorites at the URI trial were:

Golden Sweet: best flavor and appearance
Golden Rave: beautiful, flavorful, productive and consistent
Black Cherry: good flavor and appearance
Pink Beauty: similar to Brandywine with less disease and irregularity
Sakura: high productivity, good flavor

Three videos of the project were created and can be found of the University of Rhode Island YouTube channel.


Season extension practice using high tunnels has made possible ever earlier tomato sales in temperate climates, but the potential of these structures is far from being realized. Early production promotes increased tomato crop value, and because tomatoes grown under cover using intensive cultural practices are clean, have less disease (necessitating less fungicide), and have higher per-plant and per-area yields than field grown tomatoes, the profit margin is greater. Additional labor is required to achieve this more intensive approach, but with Rhode Island ranked at 2nd in the nation in unemployment, additional jobs are beneficial. Furthermore, as petroleum prices continue to climb, food security in the Southern New England region becomes an ever more prescient issue.


Tomatoes have long been a popular direct-marketed vegetable. Because Southern New England growers rely on direct marketing to a great extent (Connecticut, Massachusetts, and Rhode Island have recently ranked in the top three in the nation in direct-to-consumer sales as a percent of those states’ total agricultural sales) flavor and appearance should weigh in more heavily for variety selection than storage and shipping qualities. Nevertheless, those new to growing under cover (the NRCS-EQIP Seasonal High Tunnel Initiative has arranged for the funding of 66 structures in Rhode Island) seem to be taking field tomato varieties and field growing practices inside. The purpose of this study is twofold: 1) to conduct a grower and experimental farm trial of a dozen indeterminate varieties which are known to tolerate the unique set of environmental conditions of the high tunnel and which possess exceptional market qualities in terms of flavor, appearance, and direct-marketability; and 2) to carry out a demonstration of intensive indoor tomato cultivation methods applied to high tunnels.


Limited work has been done in the area of high tunnel variety selection in the Northeast. SARE grant ONE04-028, High Tunnel Tomato Variety Trial (New York State), looked at three indeterminate varieties and one determinate variety using greenhouse cultural methods, and successfully demonstrated overall higher yields and fruit numbers as well as greater mean fruit weights for indeterminates. SARE grant ONE05-046, Hybrid and heirloom high-tunnel tomato variety trial (also in New York State), trialed two additional indeterminate hybrids alongside of the two best yielding in the previous study, and also five indeterminate heirloom varieties. All were appropriate for fresh market, and the use of heirlooms is innovative because it creates interest and diversity on the roadside stand or CSA share. However, most of what has been trialed in high tunnels is round, red slicing varieties, such as those in these and other extension researchers’ work (Penn State University, 2010; Michigan State University, 2007; Iowa State University, 2006). Meanwhile, there are dozens of innovative and attractive varieties bearing a multitude of shapes, colors and sizes. Many are hybrids with disease resistance. Smaller fruits mean earlier ripening, which allows fresh local tomatoes to enter the market when the public is beginning to anticipate the season, which insures high salability. The trialing of such tomatoes is not meant to displace round red slicers but rather to diversify presentation and provide options for bringing tomatoes to market at the earliest possible time.


Some of the missing potential for production and sales can be made up in modification of production methods. The practices to be implemented at the experimental farm include: modification of planting date; pruning technique; and trellising with the use of “leaning and lowering.” The last involves the provision of additional vertical growing space throughout the season. This is accomplished through the use of string trellis hangers that allow for several additional feet of string to be wound upon them; as the vines grow in height, string can be unwound as the hangers are slid along overhead tunnel-length cables, which accommodate the lower portions of the plants. Some growers are using string trellis but are not lowering, which makes picking possible only from a high ladder. In some cases, the vine growth slows down to the extent that lowering is not necessary, and this is likely because plant tissue nutrients are not being maintained. A study carried out in Rhode Island (SARE grant FNE05-556, A feasible method for organic fertilization of greenhouse tomatoes through drip irrigation) demonstrated the practice of organic fertigation of tomatoes. Some growers believe that particulate matter in the drip tape is a problem but this study showed otherwise, and this practice will be used in the URI trial. As for planting date, some growers are not planting until well into the month of May, which fails to take full advantage of season extension on the spring side. Transplanting can take place in April; in the event of a few cold nights, additional winter-weight row cover will keep plants safe.

Project Objectives:

Most objectives for this project were accomplished, including:

  • Establishment of trial plantings of 13 tomato varieties at URI and at three cooperating growers’ farms
  • Introduction to growers of a broader range of variety classes suitable for high tunnels 
  • Documentation of yield, leaf tissue nutrient status, and plant growth at URI trial
  • Dissemination of techniques and production methods for high tunnel tomatoes to the greater Rhode Island vegetable farming community through various forms of outreach

Two objectives were not accomplished:

  • Tissue sampling at participating growers’ farms
  • Acceptably accurate yield data from all growers

One additional outreach objective was created and executed:

  • Production of a series of three 12-minute videos on high tunnel tomato production, viewable on the University of Rhode Island’s YouTube channel


Click linked name(s) to expand/collapse or show everyone's info
  • Dr. Rebecca Brown
  • Judith Carvalho
  • Vinnie Confreda
  • Christina` Dedora
  • Matthew Thibodeau


Materials and methods:

Materials and Methods

Concurrent studies were conducted during the 2013 growing season: a grower variety trial and a University of Rhode Island variety trial. Seedlings were raised by a Rhode Island greenhouse grower with seed provided by Johnny’s Selected Seeds.

Grower Trial

Thirteen indeterminate tomato varieties (Table 1) were grown in high tunnels on four farms in Rhode Island. The primary parameter measured was yield by variety, and general observations and preferences among participating growers were documented.  Nine seedlings of each variety were provided to each grower during the last week of April, 2013.  Most plants were set in the ground by May 1.  Fertilization and production practices varied amongst all growers.  Two utilized practices which are generally akin to organic, though neither are certified.  The other two generally used conventional fertilization and pest management, including fertigation with completely soluble plant nutrient blends.  One of these two growers sprayed fungicide on numerous occasions, although no disease pressure appeared to warrant these treatments.  One grower was an avid participant at first but when it became clear that he was unable to keep up with regular maintenance and fertilization, he was asked to drop out of the project.  The three remaining partners pruned and trellised their tomato vines in a variety of ways, though none of them used the “lean-and-lower” method.  All kept track of their harvests to greater and lesser extents, and yields reported here are not definitive.  However, all had general impressions of the relative productivity of the varieties, and their relative popularity among their customers. 

University of Rhode Island Trial

The same 13 indeterminate tomato varieties were grown in two high tunnels at the agronomy research farm at the University of Rhode Island. The primary parameters measured were yield by variety, vine length, and tissue nutrient status.

Prior to planting, beds were amended with 2” of finished compost from Earthcare Farm and dolomitic lime at a rate of 1 ton per acre.  In addition, an organic fertilizer blend was incorporated into the soil at a rate of 75 lbs. N per acre in a 12” wide band. Sixteen consecutive plants of each variety were planted on April 18, 2014, in five rows in two high tunnels on April 18, 2013.  Beds were 5 feet apart on center, and plants were spaced at 16” within the rows.  Polyester row covers over wire hoops were installed over each row. Plants were regularly pruned and maintained with one stem each.  A total of 20 feet of string was wound onto each of 220 “tomahooks,” which were hung on overhead pipes approximately 8 feet above ground level.  As plants grew, each stem was clipped to its own string. As plants reached the hanger above, additional string was unwound (lowering the growing tips) to allow continued upward growth of the stems.  Because tomato vines are only semi flexible, the hangers needed to be moved incrementally down the length of the pipes in order to accommodate the additional vine that would be lowered to the ground. Plants were drip irrigated regularly, with weekly alternating fertigations using fish emulsion, seaweed extract, liquid chelated calcium (not an OMRI approved product), and Epsom salt (Table 2). 


On May 30 and October 29, 5 vines of each variety were measured for length to determine overall vigor.  On June 12 and July 8, eight leaves of each variety were taken and held separately. Samples were dried and ground and sent for analysis to the University of Connecticut.

Tomato harvest began on June 18 and continued until a hard freeze on October 25 killed all plants and froze all green fruit.  Fruit was harvested twice weekly until late September when ripening slowed, when it was harvested once per week.  All fruit was considered marketable until the second week of July, when lower quality fruit was separated from top quality.  Any fruits which lacked structural integrity were not harvested. Harvest yield records were maintained throughout the production season.

Research results and discussion:

URI Trial

Harvest data from the URI trial is shown in Table 3.  On less than a 1/16 of an acre, 3,700 lbs of tomato were produced. Fruit production was continuous from early July until an October 25 freeze killed all plants, still heavily laden with fruit.  Most varieties performed very well, but since several tomato classes are represented, comparative rating is not possible. The only disease that was seen consistently was powdery mildew, but did not begin to be common until mid September. The disease did not appear to have affected yield. Occasional gray mold and leaf mold were also seen but only in scattered locations.

Standout varieties included ‘Golden Sweet’, ‘Golden Rave’, and ‘Sakura’.  These ripened evenly, had excellent color, flavor and holding ability, and vines remained healthy and productive until the freeze.  Two were less than satisfactory:  ‘Rebelski’ has been highly rated in other trials but in these conditions, although very productive, most fruits had green cores even when the fruit was red-ripe, and the flavor was unremarkable; ‘Indigo Rose’ was very slow to ripen, had insipid flavor and was unproductive.  Several varieties (‘Suzanne’, ‘Pozzano’, 'Pink Beauty', 'Juliet') had ripening disorders, including yellow shoulders and blotchy ripening.  This took place especially during periods of extreme heat, when watering was probably less than adequate, resulting in potassium deficiency, which is known to be associated with blotchy ripening.  Tissue testing in June and July revealed significant potassium deficiency in both samplings (Table 4). Most likely, potassium demand is excessive due to a high growth rate and heavy fruit load, leading to the ripening disorders.

Overall favorites at the URI trial were:
Golden Sweet: best flavor and appearance
Golden Rave: beautiful, flavorful, productive and consistent
Black Cherry: good flavor and appearance
Pink Beauty: similar to Brandywine with less disease and irregularity
Sakura: high productivity, good flavor

Tissue macro- and micro-nutrient levels varied little across varieties and classes on both sample dates (Tables 4 and 5). While boron and manganese concentrations were below reference values, at no time in the season did leaves or fruits exhibit any deficiency symptoms.  In addition, the generous application of compost should have easily provided all the B or Mn that plants required.  All were treated equally with soil amendments and fertigation, indicating that nutrient demand varies little between these varieties and classes, which allows for even-handed nutrient application when growing a mixture of tomato types within one high tunnel. 

Final vine lengths all ranged in the 17 to 19 foot range with the exception of ‘Indigo Rose’, ‘Clermon’, and ‘Pink Beauty’, which reached from 10 to 13 feet.  Knowing which varieties are less vigorous is important for planning space usage in the high tunnel.

Grower Trial

Three of the four growers produced tomato crops from the seedlings supplied.  All, including the fourth, found the experience to be extremely valuable, not only for improving their tomato selection criteria and production practices, but also in how they think about high tunnel production in general. This includes use of space, fertigation and water use, control of temperature, and factors influencing plant diseases.  All were intending to include some of these varieties in their 2014 growing seasons, and to incorporate “leaning and lowering” style trellising.

All grower participants were interested in customer reactions to these varieties and ‘Golden Rave’ was the most well-received among everyone’s customer base. ‘Black Cherry’ and ‘Golden Sweet’ were also standouts.  However, both of these varieties crack easily and are less productive than the other cherry varieties.

Research conclusions:

As farmland acreage in states like Rhode Island continues to shrink while prices rise, compact and intensive operations continue to grow in number. High tunnels are becoming omnipresent on Southern New England vegetable farms, and this popularity has been partly fueled by the continuation of the NRCS-EQIP High Tunnel program. Farmers have a new kind of environment in which to innovate, and practices demonstrated by this project propagate further interest and innovation. Use of intensive techniques such as fertigation, leaning and lowering, and selecting varieties appropriate for this environment, can result in high revenue on small land area.  In this case, it is possible to grow over $30,000 of tomatoes on one sixteenth of an acre.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

There were numerous outreach efforts from this project, including:


  • A twilight meeting, attended by thirty-eight people, was held at the URI Agronomy Research Farm on August 12.
  • Thirty people attended a meeting at the URI Turf Research building on November 14, which featured presentations on the current high tunnel tomato project, and greenhouse tomato production, by Dr. Richard McAvoy of the University of Connecticut
  • On March 22, 2014, a presentation on the project was given at a conference of the Southeast Massachusetts Agricultural Partnership in New Bedford, MA


  • A report on the project was published on DigitalCommons@URI in the Rhode Island Agricultural Experiment Station Bulletin, and a link to the publication was sent out on the RIAGNOTES listserv
  • The project was featured in an article by Sanne Kure-Jensen in the June 2014 issue of Country Folks Grower

Other media:

  • On February 19, 2014, three separate videos were uploaded to the University of Rhode Island Youtube channel, each dealing with separate aspects of the project (views of videos are as of June 2014)

o Tomato Trellising for a High Tunnel Environment 319 views

o Tomato Varieties for a High Tunnel Environment 271 views

o Tomato Health for a High Tunnel Environment 152 views

In addition, requests for additional information and gratitude for the work were received by emails and phone calls. This indicated that many growers were influenced by various aspects of the project and were willing to employ some or all of the practices demonstrated.

Project Outcomes

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

Tomato production in high tunnels is clearly gaining in the percentage of overall fresh market tomatoes grown in New England.  There are problems which stand out as unique to the high tunnel:

1) Maintaining adequate potassium and calcium is essential in the high intensity growing conditions of midsummer, particularly in an organic production system.  Comparisons of grafted vs. non-grafted varieties might reveal if deficiencies are root system related.  Temperature control is difficult in a passively ventilated tunnel, and this may also be related to excessive water imbalance, which can affect nutrient uptake.

2) Diseases unique to high tunnel tomatoes, such as powdery mildew, grey mold and leaf mold, can cause significant losses without proper vine management and control measures.  Better control of these diseases should be studied.

3) Many growers with high tunnels produce tomato crops, year after year, on the same soil.  While this practice is counter intuitive, no one has yet studied if there are specific significant problems with this practice.

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.