Jubilee Improved

Watermelon

Zone 1a Save Garden

Botanical illustration of Jubilee Improved

🌱 85d to harvest Vine

Sink your spoon into Jubilee Improved’s richly sweet, sunset-red flesh—juicy, fragrant, and famously crisp for a picnic watermelo…

Crop Dates

Milestone	Date
Start Indoors	Jun 1st
Last Frost	Jun 15th
Transplant / Sow Outdoors	Jun 15th
Harvest Begins	Sep 8th
Harvest Ends	Jul 15th

Crop Details

Trait	Value
Days to Maturity	85
Sun Requirements	Full Sun
Growth Habit	Vine
Support Needed	Trellis
Planting Depth	Normal
Germination Temp (°F)	75
Min Soil Temp (°F)	65
Min Night Temp (°F)	55
Harden Off (days)	12

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Frequently Asked Questions

What’s a common watermelon (Citrullus lanatus) problem, and how do I treat it?

A frequent issue is powdery mildew, which shows up as a gray-white coating on older leaves and can reduce fruit size by weakening the plant. At the first sign, improve airflow (thin any overcrowded vines) and water at the base so foliage stays dry. If needed, spray a labeled sulfur product and reapply according to the label interval, especially during humid weather.

How often should I water watermelon during the main growing phase?

During active vine growth and while fruits are swelling, keep soil consistently moist but not soggy—about 1 to 2 inches of water per week, adjusted for heat and rainfall. Water deeply 1–2 times per week rather than lightly every day, and aim for the root zone (not the leaves). About 7–10 days before harvest, reduce watering to limit watery fruit.

How can I tell when Jubilee Improved watermelon is ready to harvest?

Harvest when the ground spot (where it rests on the soil) turns from pale/green to creamy yellow, and the fruit’s skin looks dull rather than shiny. The tendril closest to the fruit should turn brown and dry, and the fruit should sound deep when tapped. Use these cues together—don’t rely on days to maturity alone.

Sink your spoon into Jubilee Improved’s richly sweet, sunset-red flesh—juicy, fragrant, and famously crisp for a picnic watermelon. The rind is bold and handsome, with dark green striping over a sturdy, well-balanced shape that slices cleanly into shareable wedges. Grow Jubilee Improved for backyard gatherings, summer fresh eating, and show-stopping fruit-forward salads and chilled drinks that celebrate its peak flavor at maturity.

Sowing Tips

Transplant Conditions

Wait until soil reaches 65°F and nights stay above 55°F before moving outdoors. Harden off for 12 days first.

Direct Sow Preferred

Sensitive roots — does not transplant well. If starting indoors, use biodegradable pots and disturb roots as little as possible when moving outdoors.

Expert Note

Start with warm soil and lots of space, and avoid chilling the plants—watermelons hate cold roots even when frost is gone.