When to plant
Start indoors 3–4 weeks before last frost, or direct sow after soil reaches 70 degrees F. Needs a long, hot growing season (70–90+ days). In zones 3–5, choose the smallest, fastest-maturing varieties and use row covers to extend the season. Full sun and very warm conditions are non-negotiable for sweet fruit.
Soil & site
Rich, sandy loam with excellent drainage. pH 6.0–7.0. Work in very generous amounts of compost. Watermelons need warm soil (70 degrees F) to thrive — use black plastic mulch to warm the bed in cooler climates. Full sun and lots of space (6–12 feet per plant for large varieties).
Feeding
Heavy feeder. Apply balanced fertilizer at planting. Side-dress with compost or apply liquid fertilizer every 2 weeks through the season. Once fruit begins to develop, a high-potassium fertilizer improves sugar content and flavor. Reduce watering as fruit matures to concentrate sugars.
Common problems
Cucumber beetles (spread bacterial wilt — most serious threat). Powdery mildew. Squash vine borers. Fusarium wilt. Anthracnose in wet conditions. In short-season climates, choosing an early-maturing variety (70–80 days) is essential for any success.
When to harvest
Multiple reliable indicators: (1) The tendril nearest the fruit turns completely brown and dry. (2) The underside spot (where the melon rests on soil) turns from white-green to creamy yellow. (3) The skin becomes dull rather than shiny. (4) A hollow thud when tapped (not a high-pitched ping). (5) The blossom end feels slightly soft. Aim for at least 3 of these 5 signs.
How to harvest
Cut from the vine with a sharp knife or pruners, leaving 2 inches of stem. Do not pull — this can crack the fruit at the stem end. Watermelon does not continue to ripen off the vine. Once cut, refrigerate and use within 2–3 weeks. Handle carefully as even slight external cracks allow bacteria to enter.
Storage & use
Whole at room temperature: 2–3 weeks before cutting. Refrigerator after cutting: 3–5 days wrapped tightly. Freeze: cube or ball, freeze on a baking sheet, bag for smoothies. Juice and lemonade. Pickle the rind. High in lycopene and vitamins A and C.
Companion planting
Nasturtiums repel aphids and cucumber beetles that also target watermelon.
Useful for growing watermelon
A few things that make this one easier — chosen for this plant, not a generic list.
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