Watermelon

Citrullus lanatus · Vegetable

A sprawling, heat-loving vine that needs a long, warm season and plenty of space. Compact 'icebox' varieties suit smaller gardens. Sweetness depends on sun and on easing off water as fruit ripens.

💧WaterDeeply 1–2 times a week (estimated)

☀️LightFull sun, 8+ hours

🐾PetsNot toxic

Care at a glance

Light: Full sun, 8+ hours
Water: 1–2 in per week; less near ripening
Soil: Sandy, well-drained, warm, pH 6.0–7.0
Temperature: Best 75–90 °F; damaged below 50 °F
Spacing: 36–60 in apart, rows 6–8 ft
Container: At least 10 gallons, for small varieties only
Harvest: 70–100 days from sowing (estimated)
Lifespan: Annual

When?

Sow outdoors 2 weeks after the last frost, when soil is at least 70 °F. Or start seeds indoors 3–4 weeks earlier in biodegradable pots (estimated).

Step by step

Warm the soil with black plastic or mulch film a week before planting.
Sow 3–4 seeds 1 in deep per hill and thin to the best 2.
If transplanting, do it gently; roots dislike disturbance.
Use row covers in cool spells, removing them when flowers appear.
Water deeply at the base, keeping leaves dry.
Set each fruit on straw or a board to prevent rot.
Cut back watering for the last 1–2 weeks; harvest when the tendril near the fruit dries.

Common problems

Flowers but no fruitPoor pollination; encourage bees or hand-pollinate female flowers.

White powder on leavesPowdery mildew; space plants and water at the base.

Bland fruitToo much water late or too little sun; reduce watering near harvest.

Vines wilting suddenlyBacterial wilt or root damage; remove affected plants, rotate crops.

Pets

Not listed as toxic to cats or dogs; rind and seeds may upset the stomach. If in doubt, ask your vet.

Similar plants

Pumpkin Cucumber Zucchini

Sources

ASPCA — Toxic and Non-Toxic Plants

This page is general guidance; no pesticide doses are given.