Watermelon is a hot weather crop and needs lots of room to sprawl. Direct sow seeds outdoors once warm summer weather has arrived (minimum soil temp of 65° in early June). Keep seeds moist until germination. Or, start seeds indoors 5/7 in small biodegradable pots (because watermelons do not like their roots disturbed during transplanting) into a good starting mix. Ideal temperature for germination: 85-95° (use heating mat). Watermelon seedlings are sensitive to damping off fungus so keep soil lightly moist but not too wet and use an oscillating fan (set to low) to provide good air circulation. Days to germination: 4-5. Once 2 leaves appear, grow plants at a cooler temperature (around 72°). Do not let plants become pot-bound in their pots. Transplant seedlings outdoors, pot & all, early June. Protect plants from cucumber beetles by covering seeds/seedlings with row cover fabric at planting. Protect plants from groundhogs and deer.
Check for 3 signs of watermelon ripeness 1) when spot on the bottom of fruit begins to turn from white to yellow 2) the tendril near main stem has turned brown 3) fruit has a hollow sound when knocked or flicked. Do not let fruit over-ripen on the vine.
Watermelons are insect pollinated and will cross with all other watermelon varieties (Citrullus lanatus) within ½ mile (or let the watermelon varieties cross and see what you get!) Minimum population size: 6-25 plants. Always select seeds from the best plants. Rinse and dry seeds from ripe melons.