Important notes
temperatures below 10 °C: Watermelon is very heat-loving and completely frost-tender. Growth stalls below 10 °C; only plant out once it's reliably warm. ↗
indoors / no insects: The plant is monoecious (separate male and female flowers). Without insects it sets no fruit — indoors, hand-pollinate every female flower or you get no melons. ↗
Light
Full sun, 8+ hours daily. Indoors, a strong grow light — watermelon is a real light-hog.
Watering
Water generously and evenly, especially during fruiting. Ease off slightly as fruit ripens to boost sweetness. Keep foliage dry (mildew).
Temperature
Optimal 21–30 °C (70–86 °F). Stalls below 10 °C, frost kills it. Warm roots matter.
Humidity
Medium (50–70%). Too dry invites spider mites, too humid invites fungal disease.
Target values by method & stage
| Stage | pH | EC (mS/cm) | Water °C | Air °C | Humidity % | Light h | Duration (days) |
|---|---|---|---|---|---|---|---|
| Germination | 6–6.8 | — | — | 24–30 | 60–75 | 14 | 8 |
| Vegetative | 6–6.8 | — | — | 21–30 | 55–70 | 14 | 35 |
| Flowering | 6–6.8 | — | — | 21–30 | 50–65 | 14 | 14 |
| Fruiting | 6–6.8 | — | — | 22–32 | 50–60 | 14 | 35 |
| Stage | pH | EC (mS/cm) | Water °C | Air °C | Humidity % | Light h | Duration (days) |
|---|---|---|---|---|---|---|---|
| Vegetative | 5.8–6.2 | 1.5–2.5 | 20–24 | 22–30 | 55–70 | 14 | 35 |
| Flowering | 5.8–6.2 | 2–2.5 | 20–24 | 22–30 | 50–65 | 14 | 14 |
| Fruiting | 5.8–6.2 | 2.5–3.5 | 20–24 | 22–32 | 50–60 | 14 | 35 |
| Stage | pH | EC (mS/cm) | Water °C | Air °C | Humidity % | Light h | Duration (days) |
|---|---|---|---|---|---|---|---|
| Vegetative | 5.8–6.2 | 1.5–2.5 | 20–24 | 22–30 | 55–70 | 14 | 35 |
| Flowering | 5.8–6.2 | 2–2.5 | 20–24 | 22–30 | 50–65 | 14 | 14 |
| Fruiting | 5.8–6.2 | 2.5–3.5 | 20–24 | 22–32 | 50–60 | 14 | 35 |
Common problems
No fruit despite flowers (no pollination), powdery mildew, spider mites in heat, wilt from cold roots or waterlogging, fruit splitting from uneven watering.
Space & Size
- Final height
- 30 cm
- Final width
- 180 cm
- Spacing
- 90 cm
- Root depth
- 45 cm
- Min. container (Soil)
- ≥ 30 L
- Min. container (DWC)
- ≥ 20 L
- Min. container (Drip)
- ≥ 20 L
Pests & diseases
| Pest / Disease | Symptom | Organic treatment |
|---|---|---|
| Aphids | sticky leaves, virus spread | rinse off, beneficials, neem |
| Spider mites | fine webbing, speckled leaves (hot/dry) | raise humidity, predatory mites |
| Cucumber beetles | holes in leaves/flowers, spread wilt | hand-pick, yellow traps, fleece until flowering |
| Powdery mildew | white coating on leaves | airflow, remove affected leaves |
| Fusarium wilt | wilting vines despite moist soil | resistant varieties, crop rotation |
| Anthracnose | dark sunken spots on leaves and fruit | keep foliage dry, remove affected parts |
Edible parts
- Fruit · edible from Fruiting — the ripe flesh
- Seeds · edible from Fruiting — seeds edible when roasted
Yield techniques
Let 2–4 fruits ripen per compact plant and thin the rest. Hand-pollinate female flowers in the morning. Rest ripening melons on a board or fleece (rot). Raise EC during fruiting (potassium).
Propagation & pollination
- Method
- seed
- Germination time
- 8 days
- Germination temp
- 24-30 °C
- Sowing depth
- 2 cm
- Pollination
- monoecious
- Hand pollination needed
- yes
Start warm (min. 24 °C). Roots dislike disturbance — grow in plugs/peat pots and transplant gently.
Companion planting
Not yet linked: Tropaeolum majus, Tagetes patula, Phaseolus vulgaris, Solanum tuberosum, Cucumis sativus
Flavor
very sweet, juicy, refreshing
Storage
Whole melon keeps cool and dark for several weeks; cut, cover and refrigerate for 3–4 days.
History
Watermelon originally comes from Africa and has been grown for over 4,000 years — ancient Egyptians even placed them in pharaohs' tombs. Over centuries it was bred from a rather bland, pale fruit into the sweet, bright-red melon we know today.
Nutrition
Over 90% water, supplying vitamin C and A plus the antioxidant lycopene (the red flesh). Refreshing and low in calories.
Sources
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