How to Propagate Seedless Watermelon

Seedless watermelon has crisp flesh and no true seeds.

Seedless watermelons are a summer favorite. The "mule" of the watermelon family, seedless watermelons are created by crossing a watermelon with two sets of chromosomes with a watermelon with four sets. The resulting plant carries three sets of chromosomes and is sterile. Even though some seedless watermelons have soft white seeds, they cannot be saved for starting new plants. Seed has to be purchased new for each plant you intend to grow.

Things You'll Need

• Soilless seedling medium
• Seedling trays with individual sections
• Seedling germination heat pad
• Probe-style thermometer
• Seedless watermelon seeds

Instructions

1. Fill seed-starting trays with a soilless seed-starting medium, packing the medium firmly enough that there are no air gaps. Place the trays on top of heating pads designed for seed germination or use warm water to bring the soil temperature to 85 to 95 degrees Fahrenheit. Check the temperature with a thermometer; correct temperature is vital.

2. Ensure the proper amount of moisture is in the soil by taking a little bit and squeezing it together. Allow the soil to dry until it just holds its shape when squeezed. Maintain proper moisture and soil temperature throughout the first four days for proper seed germination.

3. Seed the starter cells with watermelon seeds, one to a section, with the pointed end up or at an angle. Place the pointed end 1/4 to 1/2 inch below the top of the soil. Knick the round end prior to planting to increase the rate of water uptake if you only plan to grow a few plants.

4. Maintain the temperature and moisture level for the first four days, or until 30 to 40 percent of the seedlings have germinated. Reduce the temperature of the soil to 70 to 80 degrees after germination, but continue with the original moisture level. Transplant at three to four weeks old, once two or three true leaves have formed.

References

• North Dakota State University; Propagation of Seedless Watermelon; Beth Peske
• Purdue University Extension; Seed Germination and Health of Triploid (Seedless) Watermelons; Daniel S. Egel; September 1999
• University of Nebraska Lincoln; Growing Seedless (Triploid) Watermelons; Laurie Hodges; September 2007