Hort. Series # 250
Principal Investigators: Jonathan R. Schultheis, Professor and Extension Specialist, Department of Horticultural Science, NC State University; Stuart W. Michel, Research Technician, Department of Horticultural Science, NC State University; Brandon K. Parker, Research Associate, Department of Horticultural Science, NC State University; Baker E. Stickley, Research Assistant, Department of Horticultural Science, NC State University.
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Acknowledgements
We gratefully acknowledge the assistance of Hunter Barrier (Superintendent) and Wesley Hairre (Horticulture Supervisor), Horticultural Crops Research Station, Clinton, NC, as well as the personnel at the research station for their help in establishing, maintaining, and harvesting the 2025 cultigen evaluation study. We want to acknowledge summer employees Ariana Phouangkeo, Cameron Roberts, Dylan Orechovesky, and Isabella Johnson for their assistance with this study. The cooperation and support of Hazera, Known You Seeds, Origene Seeds, Rijk Zwaan, Seminis, and Syngenta were also appreciated. We also want to thank Joy Smith for performing the statistical analysis and aiding in the interpretation of the data collected from this study.Disclaimer
This publication presents data from the mini size triploid watermelon cultigen evaluation study conducted during 2025. Information in this report is believed to be reliable but should not be relied upon as a sole source of information. Limited accompanying detail is included but excludes some pertinent information, which may aid interpretation.Financial Support
In addition to seed companies, this research was supported by the College of Life and Agricultural Sciences, North Carolina Agriculture Research, the North Carolina Cooperative Extension Services, and the North Carolina Department of Agriculture and Consumer Services. This work was in part supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under award number 2020-51181-32139.Introduction
In 2023-2024, about 328 million pounds of mini watermelon were sold in retail markets in the U.S. In 2024-2025, approximately 323 million pounds of mini watermelon were sold, demonstrating a 1.4% decrease from the previous year. In 2024-2025, mini watermelon accounted for 9.4% of watermelon sales in the U.S. The national average price of mini watermelon per pound increased by $.01 as well, from $.80 in 2023-2024 to $.81 in 2024-2025.In 2023-2024, approximately 46.7 million pounds of mini watermelon were sold in retail markets in the Southeast. This decreased by 8.1% in 2023-2024, with approximately 42.9 million pounds sold. In 2023-2024, mini watermelon accounted for 9.2% of all watermelon grown in the Southeast.
Retail scanner data shows an increasing demand for mini watermelon in the Great Lakes and Plains regions of the US, by 11.7% and 7.7% respectively, a decrease in demand in the California, Midsouth, Northeast, Southcentral, Southeast and West regions of the US, by .6%, .1%, 2.4%, 1.2%, 8.1%, and 8.8% respectively. In North Carolina, demand for mini watermelon decreased by 2.3% in the Charlotte area and by 2.7% in the Raleigh/Greensboro area following a year of high growth in the 2023-2024 season in the same markets.
In 2025, Dr. Schultheis and the Cultural Management Program in the Horticultural Sciences Department at NC State University conducted an evaluation of 7 mini size triploid (seedless) watermelon cultigens from 6 seed companies at the Horticultural Crops Research Station in Clinton, NC. The watermelon entries were evaluated for yield and quality characteristics such as soluble solids (sweetness or Brix), color, firmness, and hollow heart. The methods, results, and representative photos are presented below (Figures 2-9).
Materials and Methods
Sowing and Field Preparations
Once all seeds were received from participating companies, they were planted into 72-cell poly trays to grow transplants (Hummert Int.; Earth City, MO). The watermelons were sown on 25 March 2025. The trays of sown seeds were placed in a germination room for 48-72 hours, and moved to the greenhouse once 30-40% of seeds in each tray had germinated. Temperature in the germination room was kept between 85-90°F and humidity was kept between 85-90%. The planting medium used was a ‘fine germinating mix’, a commercial soilless mix (SunGro, Agawam, MA). After germination, transplants were moved to a greenhouse set to 85°F and hand watered twice daily. The seedlings were fertilized at least once a week with 20-10-20 water soluble fertilizer at a rate of 200-250 ppm.The field planting site was located at the Horticultural Crops Research Station in Clinton, NC. The watermelons were planted in blocks R5 and R10; a Norfolk and Orangeburg Loamy Sand type soil. Fertilizers (10-10-10-0 at 500 lb/ac and 0-0-21-21 at 200lb/ac) were applied on 3 April 2025. Pic 60 (29 gal/ac) was sprayed to fumigate the study area on 15 April 2025 for weed and nematode control. Black polyethylene plastic (1.25 mil thick, high density plastic film, 54 inches wide; TriEast Ag Group, Inc., Clinton, NC) was laid on 15 April 2025.
Transplanting and Vine Training
The mini triploid watermelon transplants were established in the field on 5 May 2025. Plot size for mini triploid watermelons was 1 row, 10 triploid plants per row with an additional 4 pollenizers, 21 feet long with alleys of 10 feet between plots. Row middles were 10 feet and in-row spacing was 1.5 feet. Stand counts were taken one week after planting with no plants needing to be replaced. ‘SP-7’ and ‘Wingman’ (4 plants/plot) were used as the pollenizer plants in this study. ‘SP-7’ pollenizers were planted after triploid plants 1 and 7 while ‘Wingman’ pollenizers were planted after triploid plants 4 and 10 in each plot. Once vines had grown over the plastic mulch, they were gently turned/trained back into the plot each week. This aided harvest by avoiding mixing cultigens and reducing vine damage at harvest.Fertilizer and Pest Management
A total of 50 lb/ac N, 50 lb/ac P, 92 lb/ac K, 42 lb/ac S, and 20 lb/ac Mg were all applied broadcast (pre-plant) to the entire study area. Drip tape (NETAFIM, 12 in spacing, 0.24 gph; NETAFIM, Tel Aviv, Israel) was installed beneath the black plastic mulch to fertigate the crop throughout the growing season. Liquid fertilizer with 4-0-8 analysis was applied through drip tape fertigation 15 times at rates of 20, 25, or 35 gal/ac, and a final fertigation at a rate of 8.41 gal/ac. Cumulative totals, pre-plant and through the drip tape, of applied fertilizer nutrients were: 183.87 lb/ac N, 50 lb/ac P, and 359.75 lb/ac K.Herbicides (Table 1), insecticides (Table 2), and fungicides (Table 3) were applied as needed and as directed by the label for that crop (2025 NC Ag Chem Manual), along with adjuvants and surfactants as necessary (Table 4). Different products were rotated to avoid potential development of resistance.Weather
Weather was fairly consistent during the growing season, with no considerable periods of drought or flood conditions in the study. A total of 22.74 inches of rain occurred at the field planting site in Clinton, NC throughout the duration of the study (Figure 1).Study Design and Data Collection
The study used a randomized complete block design with 4 replications. There were a total of 6 harvests collected each week over 42 days (1 July through 12 August). Fruits were picked when signs indicated they were ripe; yellow to tan ground spot, dead tendrils, ribbing, color. Fruits were counted and weighed individually. Fruit with pest damage and/or rot were weighed and counted if the fruit was intact and representative of the rest of the plot. Vines were moved to cover unpicked fruit that were exposed during the harvests.Quality Evaluations
Measurements were taken on 12 fruit (3 per replication) of each cultigen to determine the fruit size, fruit shape, soluble solids (sweetness or Brix), interior flesh firmness, flesh color, rind thickness, seed trace size, hard seed population, and hollowheart. The most representative fruits were selected for quality measurements and measurements were retaken on another fruit if necessary. Soluble solids were measured by cutting a piece of flesh from the center of the fruit and squeezing out the fruit juice onto the digital refractometer (Atago, Vernon Hills, IL). Flesh firmness was taken using a Penetrometer FT 011 with a 7/16’ plunger tip (QA Supplies LLC, Norfolk, VA) and was recorded in pounds. Samples were obtained by cutting the center of the fruit from the stem to blossom end. Pressure was then taken in five areas of the fruit: stem end, top side, ground spot side, blossom end, and center. The reported measures on flesh firmness are an average of the five sample areas. Hard seeds in triploid fruit were determined according to the USDA standards. Fruits were cut longitudinally in half, halves were cut longitudinally once more, and one quarter was cut laterally. The number of hard seeds exposed on the cut surface were counted and recorded. Most of the quality measurements were taken in the first harvests (1-3). Additional information on the quality measurements is presented in the Quality section on pages 7-8 and in Tables 8 and 9.Results and Discussion
Consistent precipitation, and relatively normal temperatures resulted in considerable improvement in yields when compared to previous years.For the analysis, fruits were placed in the following size categories: < 3 lb, 3 – 7 lb, 7.1 – 9 lb, and ≥ 9 lb. Fruit below 3 lb and greater than 9 lb were considered unmarketable in the mini watermelon category.Cumulative Harvests (1-6)
Yield: Pounds per acre
‘ORS 71075a’ from Origene had the highest marketable yield out of all 8 entries in this study at 37,117 pounds per acre (lb/ac) (Table 5). ‘Altata’ from Rijk Zwaan ranked second with a marketable yield of 35,708 lb/ac, and ‘ORS 71073a’ from Origene ranked third with a marketable yield of 34,336 lb/ac. The average marketable yield across all entries was 31,780 lb/ac. ‘Tropical Honey’ from Seedway and ‘Lunalinda’ from Seminis produced over 20,000 lb/ac of oversized fruit (≥ 9.1 lb) that were not considered marketable as mini watermelons, otherwise these cultigens would have been ranked higher. Similarly, ‘Queenlet’ and ‘Altata’ produced more than 10,000 lb/ac of oversized fruit, impacting their rankings.Yield: Number per acre and number of fruit per plant
The cultigen ‘ORS 71075a’ from Origene had the highest number of marketable fruit per acre (Mkt no/ac) at 7,079 fruit/ac (Table 6). ‘ORS 71073a’ from Origene ranked second at 6,752 fruit/ac and ‘Petite Perfection’ from Syngenta ranked third at 6,643 fruit/ac. The average number of marketable fruit per acre across all 8 cultigens was 6,507 fruit/ac.‘ORS 71075a’ ranked highest for both number of fruit and pounds of fruit per acre. Larger cultigens such as ‘Lunalinda’ and ‘Tropical Honey’ had a lesser number of fruit per acre due to a larger average fruit size and thereby reduced fruit set. ‘Altata’ and ‘ORS 71075a’ both had the greatest number of fruit per plant at 2.7, while ‘Tropical Honey’ had the lowest number of fruit per plant at 1.9. The average number of fruit per plant across all entries was 2.4.Yield: Average Fruit Size and Distribution
Entries fell into three average fruit size categories in general: ‘Tropical Honey’ and ‘Lunalinda’ were on the upper range for mini watermelons at 8.2 lb/fruit and 7.9 lb/fruit, respectively. ‘Altata’, ‘Queenlet’, and ‘Extazy’ are considered typical for mini watermelons, with ‘Altata’ and ‘Queenlet’ both averaging 6.7 lb/fruit and ‘Extazy’ averaging 6.0 lb/fruit. Lastly, ‘ORS 71075a’, ‘Petite Perfection’, and ‘ORS 71073a’ are on the smaller side for mini watermelons, with ‘ORS 71075a’ and ‘Petite Perfection’ both averaging 4.9 lb/fruit and ‘ORS 71073a’ averaging 4.7 lb/fruit. The average fruit size across all 8 cultigens was 6.0 lb/fruit (Table 7).Some cultigens had fruit that were unmarketable as mini size watermelons as they were greater than 9 lbs. 46% of ‘Tropical Honey’, 45% of ‘Lunalinda’, and 24% of ‘Altata’ fruit were in the greater than 9 lb (≥ 9 lb) size category. On average, across all 15 cultigens, 19% of fruit were oversized and therefore unmarketable as mini watermelons. Most fruit were in the 3-7 lb size category.Quality
‘Petite Perfection’ from Syngenta had the highest Brix or sugar content across all 9 cultigens at 12.5, followed by ‘Tropical Honey’ from Seedway and ‘Lunalinda’ from Seminis, both at 12.4 (Table 8). The average sugar content across all entries was 11.8. ‘Petite Perfection’ from Syngenta, ‘Tropical Honey’ from Seedway, ‘Lunalinda’ from Seminis, and ‘Queenlet’ from Known You Seed all had sugar contents above the average.‘ORS 71075a’ and ‘ORS 71073a’ from Origene had the two firmest flesh ratings across all 8 cultigens at 3.9 lb and 3.6 lb, respectively (Table 8). The average firmness of all entries was 3.0 lb.
‘ORS 71075a’ had the highest flesh color rating out of all 8 entries at 4.5; color is based on a 1 to 5 scale with 1 being pale or white and 5 being a deep blood red for red (Table 8). The average flesh color rating for all entries was 4.2. Tropical Honey was not given a number value for flesh color as a yellow flesh melon - instead qualitative descriptors were noted.
‘Petite Perfection’, ‘ORS 71073a’, and ‘ORS 71075a’ had the smallest rind thickness measurements on average across all entries at 9 mm, 12 mm, and 13 mm, respectively (Table 8). The average rind thickness across all 8 entries was 15 mm.
‘Altata’ from Rijk Zwaan and ‘Petite Perfection’ had the lowest hard seed populations across all 8 entries at 0 and 0.1, respectively (Table 8). Hard seed population was low overall, with an average population of 1.1 across all 8 cultigens.
‘ORS 71075a’ had the smallest seed trace across all entries at 1.3; seed trace was measured on a 1-5 scale with 1 being small and 5 being large (Table 8). ‘Queenlet’ had the largest seed traces on average at 2.1. Overall, seed traces were small, with an average size of 1.7.