Production, Marketing and Financial Analysis of Seedless Watermelons Growing in Tobacco Transplant Greenhouses

Final Report for OS02-001

Project Type: On-Farm Research
Funds awarded in 2002: $12,118.00
Projected End Date: 12/31/2004
Region: Southern
State: Virginia
Principal Investigator:
Scott Jessee
Virginia Polytechnic Institute & State Univ.
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Project Information


Burley tobacco producers in Southwest Virginia have a tremendous investment in greenhouses for the production of transplants. These houses are only used for four months of the year. Tobacco quota has been significantly reduced over the past seven years, thus reducing income for producers. In order to make up for lost income, tobacco transplant producers are attempting to produce an alternative crop in their greenhouses during the summer months. The Production, Marketing, and Financial Analysis of Seedless Organic Watermelons provides greenhouse owners the opportunity to use an established facility to generate additional income.


Production and marketing of burley tobacco has been a reliable source of income for farmers in Southwest Virginia for several generations. Over the past five years, tobacco production in the area has been reduced due to quota cuts (40%). Since the Tobacco Buyout Legislation was passed in 2004, tobacco continues to be in a transition state. Older producers have ceased production and younger producers are trying to determine profitability in the new marketplace. With this level of uncertainty, establishing new crops is more difficult.

Like any crop, tobacco producers have a large investment per acre of crop planted. Tobacco transplant producers have a larger investment because transplants are grown in greenhouses. These structures are used approximately 120 days each year. After transplants are removed, greenhouses set idle. Since most transplant producers are already diversified (tobacco and beef cattle), it is a challenge to find a crop that can be easily grown and marketed.

Seedless watermelon is a crop that has potential for tobacco greenhouse operators. Watermelons are relatively easy to grown in the greenhouse and they are affected little by the extreme temperatures during the hot days of summer. Market demand for seedless watermelon is known to exist and market demand for organic products is also on the rise. With these factors taken into consideration, organically produced seedless watermelons offer producers a “niche” for summer production.

Project Objectives:

•Determine if watermelons will grow in this environment
•Determine proper plant spacing and density for each house
•Learn about trickle irrigation systems
•Evaluate hydroponic organic fertilizer sources in relation with trickle system
•Analyze plant sap in order to determine nutrient levels in the plants
•Scout crop for insects and diseases
•Market melons and realize a positive financial return


Materials and methods:

During the two years of the experiment, modifications were made to the production system. Practices for year one are listed below:

Year 1

Varieties and Media
Super Sweet (Brand Variety 5244) Hybrid Triploid Watermelon Seed and Royal Majesty Hybrid Seeds were used. Super Sweet was the seedless variety and Royal Majesty was used for pollination purposes. Melons were grown in poly grow bags filled with Premier Ultra Organic Mix (media).

Planting Density
Plants were arranged in the greenhouse in parallel rows (125 melons per house – approximately 21 per row). Each house contained six rows of melons.

Irrigation and Fertility
A drip irrigation system was installed and each grow bag was connected. Water and fertilizer were injected using a Chemilizer Fertilizer Injector. Flow was regulated by a Nelson 4 Station SmartZone Controller. Fertrell’s Organic Fertilizer was used throughout the experiment. Macro and micro nutrients were provided as well as natural bacteria and enzymes.

Monitoring Fertility
Since we were unfamiliar with the availability of organic nutrients, fertilizer was injected at each scheduled watering. Plants were watered at ten to fifteen minute intervals three times daily. Nutrient levels were monitored by utilizing Petiole Sap Testing. By using this technique and standards derived by University of Florida, we could determine if enough nutrients were being provided.

Management and Harvest
With plenty of sunlight and a constant supply of nutrients, melons grew quickly in the greenhouse. Melons were left on the vines until the tendrils (or pigtails) were almost dry. At this stage, melons were harvested. Watermelons were delivered to a local organic marketing cooperative.

Year 2

Varieties and Media
Super Sweet (Brand Variety 5244) Hybrid Triploid Watermelon Seed and Royal Majesty Hybrid Seeds were used. Super Sweet was the seedless variety and Royal Majesty was used for pollination purposes. Melons were grown in media labeled as organic from Harvest Farms. Plants were grown in the bags in which the media was shipped (not transferred to poly grow bags). Bags were placed on the floor and holes were melted through the plastic using a small propane torch. Watermelon plants were placed directly into the media through the hole.

Planting Density
Plants were arranged in the greenhouse in parallel rows (264 melons per house – approximately 44 per row). Each house contained six rows of melons – two melons per bag. Due to differing sizes of greenhouses, area was calculated and plants were distributed to maximize area per plant.

Irrigation and Fertility
The drip irrigation system was re-installed and used for the second year. A drip emitter was placed in the center of each media bag. Water and fertilizer were injected using a Chemilizer Fertilizer Injector. Flow was regulated by a Nelson 4 Station SmartZone Controller. Neptune’s Harvest Organic Fertilizer (fish emulsion blend) was used throughout the second year of the experiment.

Melons were monitored in a manner similar to that as described in Year 1.

Research results and discussion:

Results and Discussion

Organic Seedless Watermelons have potential to generate additional summer income for tobacco transplant greenhouse owners. During year #1, watermelons were transplanted and organic fertilizer was applied with the drip irrigation system. Producers experienced difficulties with the injector system due to the thickness of the fertilizer mixture.

Plant nutrient levels were monitored throughout the season using Plant Petiole Sap Testing (Plant Petiole Sap Testing, University of Florida Circular #1144). As the fertilizer injector became clogged and nutrient flow was decreased, plant nutrient levels were reduced. When the system was disassembled and cleaned, spikes in nutrient levels were apparent. The changes in plant growth pattern could be detected visually as well as through the nutrients extracted from petiole sap.

To help alleviate the fertilizer problem, one producer diluted the fertilizer mixture and added a small circulation pump. This solution helped to alleviate the problem.

Powdery mildew became a problem in early August. At this time of year, Southwest Virginia is noted for heavy fog. Many mornings the fog does not dissipate until 10:30 a.m. The presence of the pathogen and excess moisture caused problems for the crop. Several organic compounds were tried, but they were unsuccessful. Preventative sprays with organically certified fungicides are necessary to prevent powdery mildew.

Withstanding several minor problems, the seedless plants did produce melons. Melons were monitored and harvested when the tendrils began to dry. Due to nutrient availability problems and the low density of plant per house, there were never enough melons ripe at any one time to fill a produce bin. By waiting for the majority of the house to become ripe, several of the melons were harvested too late. Despite the best efforts of our local organic marketing cooperative, it was difficult to market the melons.

In year two several modifications were made to the production system. After Bovine Spongiform Encephalopathy was discovered in Canada, we could not obtain the Premier Media. Because this media contained a bovine byproduct, it could not be transported across the border. Harvest Farms Organic Media was purchased and used in the experiment. This media was not as suitable as the Premier Brand, which is reflected in production.

To alleviate problems with the fertilizer mixture, Neptune’s Harvest Fish Emulsion was used. The analysis of this fertilizer was similar to the brand used in year number one, and it was more “injector-friendly.”

Melons were transplanted and monitored. Growth with the new media and fertilizer was not as vigorous as the year before. Because two variables had been modified, it is difficult to pinpoint the major growth limiting factor. Melons were watered and irrigated on a similar schedule, but the plant showed nutrient deficiency symptoms throughout the summer. Since the plants were stressed and not growing at their optimum genetic ability, no marketable melons were produced.

Agriculture producers are very adaptable and they are willing to try new crops. Although learning new production practices and quality standards takes time, they can be attained. Based on the successes of year one, it is proven that watermelon can be produced in tobacco transplant greenhouses. As with most crops, marketing at a profitable level creates the major problem. With any new crop, it is likely that the producer will lose money in the first years of production. If additional research is conducted to alleviate the minor production problems, organic seedless watermelon production offers greenhouse owners the opportunity to generate extra income during the summer months.

Participation Summary

Project Outcomes

Project outcomes:

Economic Analysis

Year #1
All expenses and inputs were recorded throughout the production cycle. Expenses for the irrigation system were pro-rated. With production levels described in year one, it is projected that expenses will be recovered over a five year period. During the first year of the experiment, a positive return was generated despite the low population density of plants.

An Excel Spreadsheet was developed to further analyze this data. Plant Densities, melons produced per house, etc. are incorporated into the spreadsheet. At the density of 125 plants per house, a profit of $42.59 can be generated. If population densities can be increased (by 140 plants – 6 rows per house with 2 plants per bag), there is potential to generate an additional $700.00.

Year #2
Due to problems with the media and fertilizer, there were not any watermelons suitable for retail sale. Although the producers and support team was discouraged, this is typical of what a producer might experience in the real world.


Areas needing additional study

Organic Fertilizers and Drip Irrigation:

Drip irrigation is a common tool used in fruit and vegetable production. The use of organic fertilizers in the drip system caused problems during the growing season. Due to product thickness, the injector was clogged numerous times. This interrupted the flow of nutrients to the plants, thus reducing yield potential. Additional work needs to be done to determine which organic fertilizers are compatible with drip systems. This will allow other organic producers to utilize modern irrigation technology.

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.