Cucurbit Genetics Cooperative Report 2:27 (article 16) 1979
Growing Seedless Hybrid (triploid) Watermelons by Direct Seeding
H. H. Partridge
Munday Vegetable Growers Co-op, Munday, TX 76371
To be successful in growing seedless hybrid (triploid) watermelons by direct seeding, it is necessary to alter cultural practices normally used in growing the common diploid watermelon.
Many growers have failed in their attempts to grow triploids because they are geared to cultural practices that are normally used in growing diploid watermelons. This is understandable since it is necessary to interplant a diploid pollinator either in adjacent rows or within the row with the sterile triploids. Also, the grower feels more comfortable in using such cultural practices he knows will work on diploid watermelons.
There are several reasons why triploid watermelon culture is different from diploid watermelon growing: 1) triploid seeds will not germinate in cold, wet soils as well as diploid seeds; 2) triploid seedlings will not tolerate high soil moisture conditions between the seedling stage and runner development; 3) fruit set on triploid plants is later than most diploid cultivars; and 4) triploid plants are vigorous, long season, and productive.
We recommend the following cultural practices for growing direct seeded triploid watermelons. Land preparation: 1) prepare land similar to diploid production; 2) bed land in 38" or 40" rows; 3) in every other bed where seeds are to be planted, fertilize with 200 pounds of 16-20-5 and shape beds for top of bed planter; and 4) irrigate before planting if necessary. Planting: 1) plant two or three weeks after last freeze, usually about April 15 in our location; 2) hand plant two seeds per hill three feet apart in the row alternating one hill diploid with three hills triploid. Thus, the planting pattern is one diploid to three triploid hills within the row with the rows 78" or 80" apart or about 2,200 hills per acre.; 3) after plants have started running, fertilize with 200 pounds of ammonium sulfate per acre or about 40 pounds actual nitrogen; 4) bust out blank beds making 78" or 80" beds; 5) apply herbicide (Dacthal); and 5) irrigate as needed to maintain good plant growth.
Harvest usually starts in our location about July 20. Yields will exceed 30,000 pounds of triploid and 8,000 pounds of diploid watermelons per acre under normal growing conditions.