Watermelon Citrullus lanatus
Watermelon (Citrullus lanatus) is an annual vegetable in the Cucurbitaceae family, native to Tropical and southern Africa. It grows 30–50 cm (12–20 in) tall and 1.5–3 m (4.9–10 ft) wide, wants full sun and moderate water, and is hardy to about 2 °C (36 °F). Space plants about 1 m (3.3 ft) apart.
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Watermelon at a glance
| Type | Annual vegetable |
|---|---|
| Family | Cucurbitaceae |
| Mature height | 30–50 cm (12–20 in) |
| Mature spread | 1.5–3 m (4.9–10 ft) |
| Spacing | 1 m (3.3 ft) centre to centre |
| Sun | Full sun, at least 8 h of direct sun a day |
| Water | Moderate; drought tolerance moderate, waterlogging tolerance none |
| Soil pH | 6–6.8 |
| Cold hardiness | About 2 °C (36 °F) once established (roughly USDA zone 10) |
| Heat stress | Likely above about 38 °C (100 °F) |
| Flowering | about 5–8 weeks after planting, for 6–10 weeks |
| Days to maturity | About 90 days from planting |
| Wind tolerance | Low |
| Pollinator value | Moderate |
| Edible | Yes: fruit flesh, seeds, rind (pickled) |
| Native to | Tropical and southern Africa |
| Common in gardens of | 🇺🇸 United States, 🇨🇳 China, 🇧🇷 Brazil, 🇲🇽 Mexico, 🇿🇦 South Africa, 🇹🇭 Thailand |
Is Watermelon toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Flesh is safe; the rind and many seeds can cause stomach upset or blockage in pets.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Watermelon
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Keep apart or take care
- caution With Cucurbits (squash family): Cucurbits share powdery mildew, cucumber beetles and mosaic viruses; good airflow and spacing reduce spread. Evidence C
Shared pests and diseases
- Powdery mildew: Powdery mildew spreads between cucurbits in warm, dry weather. Evidence C
Questions about Watermelon
- How far apart should I plant Watermelon?
- About 1 m (3.3 ft) apart, centre to centre. A mature plant spreads 1.5–3 m (4.9–10 ft).
- Does Watermelon need full sun?
- Full sun: at least 8 hours of direct sun a day.
- How much water does Watermelon need?
- Moderate water. Drought tolerance is moderate and waterlogging tolerance none.
- How cold-hardy is Watermelon?
- It tolerates about 2 °C (36 °F) once established, roughly USDA zone 10. As an annual it is usually planted out after the last frost.
- When does Watermelon flower?
- About 5–8 weeks after planting, for 6–10 weeks.
- Is Watermelon poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Flesh is safe; the rind and many seeds can cause stomach upset or blockage in pets.
- What grows well with Watermelon?
- There is no well-documented companion pairing for Watermelon. Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- FAO Irrigation and Drainage Paper 56 — Crop Evapotranspiration, FAO
- University extension gardening guides (general), Various land-grant university extensions
- EcoCrop crop environmental requirements, FAO
Notes and assumptions
- Needs warm soil and a long hot season; in cool climates use transplants on black plastic or small icebox types.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Cucumber Cucumis sativus
- Zucchini (courgette) Cucurbita pepo
- Pumpkin Cucurbita maxima / C. pepo
- Muskmelon (cantaloupe) Cucumis melo
- Butternut squash Cucurbita moschata
- Bitter melon Momordica charantia
- Luffa (sponge gourd) Luffa aegyptiaca
- Bottle gourd Lagenaria siceraria