Type: Hybrid
Relative Days: 74
Rind Type: Light green with dark green stripes
Size: 5.5-6.5 lbs.
Shape: Globe
Flesh Color: Red
Life Cycle: Annual
Watermelon Classification: Seedless (Triploid)
Characteristics:
Sirius F1 is a hybrid seedless (triploid) watermelon that matures in about 74 days, producing globe-shaped, personal-sized fruits weighing 5.5-6.5 pounds. The light green rind with dark green Crimson Sweet-style stripes is medium thick, giving the fruit durability without sacrificing eating quality. Inside, the red flesh has excellent color, flavor, and texture with small to medium pip size. Plants show good vigor and yield uniform fruit size, with intermediate resistance to Fusarium wilt race 1. Sirius F1 is a reliable, high-quality personal watermelon that combines appearance, taste, and strong performance.
Seedless Watermelon (Triploid)
Triploid watermelons are sterile and do not produce viable seed. They require a pollinator variety planted in alternating rows (e.g., 1 pollinator for every 2 rows of triploid). Direct seeding is not recommended due to poor emergence in temperatures below 80ºF and thick seed coats that may stick to cotyledons, causing damage.
Temperature
Germinate seeds at 90ºF. In cooler areas, warm transplant flats in the sun or use dark rooms with 90ºF and 95% humidity. Emergence takes 4–5 days. Transplants are grown for 3 weeks before setting in the field.
Soil
Plant in well-drained sandy loam, preferably not used for cucurbits in the past 5 years. Use raised beds to improve early-season warmth and drainage. Avoid compaction and monitor moisture during seedling establishment.
Planting
Use transplanting only. Sow 1" deep in greenhouse. Set transplants deeper in the field than in the tray. Fully bury peat pots to avoid moisture wicking. Water transplants thoroughly to settle soil. Include pollinator rows across the field for fertilization. Melons from pollinator rows should be distinct and market-acceptable.
Spacing
24–48" in row and 72" between rows
Pollination
Triploid watermelons produce little or no pollen and rely on seeded pollinators. One strong bee hive (30,000–50,000 bees) per 1–2 acres is recommended. Plant pattern: outer beds as pollinators, then two rows of triploid, one row of pollinator, and repeat. Ensure pollinators are distinguishable at harvest.
Harvest
Harvest when the tendrils are brown, the ground spot turns yellow, and thumping yields a hollow sound. High-quality fruit has a sugar content of 10% or more. Use a refractometer to verify. Harvest with a knife or clippers and place bottom-down to prevent sunscald. Consume within 2–3 weeks of harvest.
Cost Considerations
Triploid production is more expensive due to seed cost, transplanting, and the need for pollinators. Growers should secure higher prices to offset these inputs. Uniform stand establishment is critical; overseeding and thinning are not cost-effective options.
For more information, please see links below:
- Penn State - Watermelon Production
- University of Georgia - Watermelon Guide
- University of Kentucky - Watermelon
Note: This information is summarized. Additional details and expanded guidelines can be found in our production sheets available in the Holmes Seed Grower's Guidebook.
Downloadable Copy: