Plant Profile

watermelonCitrullus lanatus

The watermelon (Citrullus lanatus) is a popular summer fruit that requires plenty of warmth and sun. It originates from Africa and belongs to the gourd family. With its sweet, juicy flesh, it is a refreshing delicacy on hot days. Cultivation requires patience and the right conditions, but rewards with a bountiful harvest.

CucurbitsVegetablesGourd family
Calendar
watermelon (Citrullus lanatus): plant portrait - Cucurbits, Gourd family, Harvest August - October
watermelon: plant portrait. harvest: August - October.

Quick profile

Key data

Growing calendar
JanFebMarAprMayJunJulAugSepOctNovDec
Indoor sowing
Direct sowing outdoors
Planting outdoors
Harvest
Indoor sowingDirect sowing outdoorsPlanting outdoorsHarvest

Suitable growing locations:

Outdoor garden bedRaised bedGreenhouse

Good neighbors

BeansCornRadishNasturtium

Avoid

potatoCucumberSquashPumpkin/Squash

Indoor & direct sowing

watermelon: Sowing and germination

Indoor sowing

Watermelons love warmth and should only be planted outdoors after the last frost. Pre-cultivation indoors is recommended.

Direct sowing outdoors

Direct sowing is possible when the soil has warmed sufficiently (at least 15°C). This is usually only the case from mid-May onwards.

Seed depth1 - 2 cm
Germination temp20 - 25 °C
Germination time7 - 14 days
Light germinatorYes
Dark germinatorNo
Cold germinatorNo
Stratification neededNo
Pre-soaking recommendedNo

Planting & site

watermelon: Planting and spacing

Planting outdoors

Plant the pre-cultivated seedlings outdoors or in a greenhouse after the Ice Saints (mid-May), when there is no longer any risk of frost.

Plant spacing100 - 150 cm
Row spacing150 - 200 cm
Plants per m²0.5 - 1 per m²
Bed widthfrom 120 cm

Site & practical notes

Watermelons are heavy feeders and require nutrient-rich soil and regular fertilization.Ensure a warm, sunny, and sheltered location, ideally south-facing or in a greenhouse.The plants are very heat-loving and frost-sensitive. Sow and plant out only after the last frosts.Consistent watering is crucial to prevent fruit splitting and bitterness.Adequate planting distance (1-1.5 m) is important for air circulation and disease prevention.Ripeness can be determined by tapping (dull sound) and the dryness of the tendril attachment.Choose resistant varieties to minimize problems with mildew and wilt.

Temperature & frost

watermelon: Temperature and site

Growing temperaturefrom 18 °C
Optimal temperature22 - 30 °C
Max. heatup to 35 °C
Soil temperature15 - 20 °C
Frost sensitiveYes
Late frost sensitiveYes
Heat tolerancehigh
Cold tolerancevery low

Water & nutrients

watermelon: Water, nutrients and care

Waterhigh
Critical water phasesFruit development, Growth
Watering methodWater at the base
Droughthigh
Waterlogging sensitiveYes
Mulching recommendedYes
Nutrient needheavy feeder
Compost recommendedYes
Fertilizer sensitivitylow

Container & growth

watermelon: Container, support and growth

Container suitableNo
SupportNo
Height20 - 50 cm
Width150 - 300 cm
Root depth60 - 100 cm
Root spread100 - 200 cm
Yield1 - 5 fruit

Year plan

watermelon Calendar

Plants

Enjoy the harvest in late summer when the fruits have reached their full sweetness.

Year overview
JanFebMarAprMayJunJulAugSepOctNovDec
Indoor sowing
Direct sowing outdoors
Planting outdoors
Harvest

Relevant now

June

  • Watering and fertilizingActive growth: Water regularly and deeply, especially in hot weather. Fertilize with a balanced fertilizer.
  • WeedingWeeds present: Keep the bed free of weeds to avoid competition.

Next up

July

  • FertilizingFruit development: A second fertilization can be done if needed, preferably with a potassium-rich fertilizer.
  • WateringDry weather: Especially important during fruit development. Avoid waterlogging.

Monthly tasks

Single tasks from monthly data; repeated seasonal windows are shown in the overview above.

Direct sowingPlantingHarvestGrowingPlant health

January

Quiet month

February

Quiet month

March

Sowing indoors

Direct sowing

  • Sowing indoorsSoil temperature at least 20-25°C: Watermelons are light germinators. Sow them in individual pots to avoid pricking out.

April

Pricking out

Growing

  • Pricking outSeedlings have developed true leaves: If the seedlings are too crowded, prick them out into larger pots.

May

Planting out into open ground/greenhouse

Planting

  • Planting out into open ground/greenhouseNo risk of frost, soil temperature at least 15°C: Ensure sufficient planting distance (1-1.5 m). Provide protection from wind if necessary.

June

Watering and fertilizingWeeding

Growing

  • Watering and fertilizingActive growth: Water regularly and deeply, especially in hot weather. Fertilize with a balanced fertilizer.
  • WeedingWeeds present: Keep the bed free of weeds to avoid competition.

July

FertilizingWatering

Growing

  • FertilizingFruit development: A second fertilization can be done if needed, preferably with a potassium-rich fertilizer.
  • WateringDry weather: Especially important during fruit development. Avoid waterlogging.

August

Pest and disease control

Plant health

  • Pest and disease controlSymptoms observed: Watch for signs of powdery mildew, aphids, or spider mites.

September

Harvesting

Harvest

  • HarvestingFruits ripe: Harvest ripe fruits. Protect them from heavy rain to prevent rot.

October

Final harvest

Harvest

  • Final harvestBefore first frost: Harvest all remaining fruits before the first frost.

November

Quiet month

December

Quiet month

Flowering & pollination

watermelon Flowering & pollination

Self-fertility

self-fertile

Pollinator needed

yes

watermelon (Citrullus lanatus): 2 for flowering and pollination - Cucurbits, Gourd family, Harvest August - October
watermelon: flowering and pollination. harvest: August - October.

Overview

Although watermelons are self-fertile, cross-pollination by insects, especially bees, is essential for good fruit development and size.

Notes

Bees are the primary pollinators. One bee colony per 1-2 hectares of cultivation area is recommended. Avoid using insecticides during the flowering period.

Companion guide

watermelon Companion guide

Companion guide

Good neighbors

BeansCornRadishNasturtium

Avoid

potatoCucumberSquashPumpkin/Squash

Use & storage

watermelon Use & storage

Harvest

Harvest time depends on the variety and weather conditions. Fruits are ripe when they sound dull when tapped and the tendril attachment becomes dry.

Storage

Cool and dark

Storage life

Whole fruits: 2-4 weeks under optimal conditions. Cut fruits: 3-5 days in the refrigerator.

Harvest

Harvest time depends on the variety and weather conditions. Fruits are ripe when they sound dull when tapped and the tendril attachment becomes dry.

Processing

Freezing (as puree or pieces)Canning (as jam or chutney, often combined with other fruits)Drying (less common)

After harvest

Carefully detach fruits from the stem to avoid injury. Do not wash unless consuming immediately, as this can affect shelf life. Protect from direct sunlight.

Edibility & safety

watermelon Edibility & safety

For people

In brief: which parts are edible, which parts remain risky, and whether raw consumption makes sense.

Edible parts:Flesh, Seeds (cooked or roasted), Young leaves and flowers (rarely used)
Caution parts:The white layer between the flesh and the hard rind (edible, but often tough and tasteless)
Raw consumption:The flesh is typically consumed raw. Seeds can be eaten raw but are more digestible and palatable after roasting or cooking.

Safety notes

The fruit of Citrullus lanatus is non-toxic and safe for consumption. Some wild forms or unripe fruits may contain bitter compounds.

Animal safety

This plant is not simply safe or unsafe for animals. 14 animal types have restrictions, so quantity, access, and plant part matter.

Animal safety by plant part

Each row shows which parts are more suitable and which parts are critical.

Companion animals

Dog icon for animal safety ratingDog

Flesh

Seeds, Rind

Risk factors

Excessive consumption of seeds or rind may cause gastrointestinal upset.

Symptoms

Gastrointestinal upset (if overconsumed)

usually no action needed

Watermelon flesh is safe for dogs in moderation and is commonly used as a treat. Seeds should be removed as they pose a choking hazard, although they are not toxic. The white rind between the flesh and hard shell is edible but often tough and tasteless, thus not recommended.

Open animal page
Cat icon for animal safety ratingCat

Flesh

Seeds, Rind

Risk factors

Excessive consumption of seeds or rind may cause gastrointestinal upset.

Symptoms

Gastrointestinal upset (if overconsumed)

usually no action needed

Watermelon flesh is safe for cats in moderation and can be given as an occasional treat. Seeds and rind should be avoided as they are difficult to digest and may pose a choking hazard. Cats are obligate carnivores, so plant matter should only be offered in very small quantities.

Open animal page
Rabbit icon for animal safety ratingRabbit

Flesh

Seeds, Leaves, Stems

Risk factors

Excessive consumption of seeds or leaves, Unripe fruits with higher bitter compound levels

Symptoms

Gastrointestinal upset, Diarrhea

observe

Watermelon flesh is suitable for rabbits in small amounts as an occasional treat. Seeds, leaves, and stems contain potentially harmful cucurbitacins and should be avoided. Due to high water and sugar content, feed only occasionally.

Open animal page
Guinea pig icon for animal safety ratingGuinea pig

Flesh

Seeds, Rind, Leaves

Risk factors

Excessive consumption of seeds, rind, leaves, or stems., Unripe fruits with higher bitter compound levels.

Symptoms

Gastrointestinal upset (if green parts or unripe fruits are consumed)

observe

Watermelon flesh is suitable for guinea pigs in small amounts as an occasional treat. Seeds, rind, leaves, and stems should be avoided as they may contain potentially harmful cucurbitacins. Due to high water and sugar content, feed only occasionally.

Open animal page
Hamster icon for animal safety ratingHamster

Flesh

Seeds, Rind

Risk factors

Excessive consumption of seeds or rind., Unripe fruits with higher bitter compound levels.

Symptoms

Gastrointestinal upset (if seeds or rind are overconsumed)

observe

Watermelon flesh is suitable for hamsters in small amounts as an occasional treat. Seeds and rind should be avoided as they are difficult to digest and may contain potential cucurbitacins. Due to high water and sugar content, feed only occasionally.

Open animal page
Budgie icon for animal safety ratingBudgie

Flesh (seedless)

Seeds, Leaves, Stems

Risk factors

Excessive consumption of seeds, leaves, or stems., Unripe fruits with higher bitter compound levels.

Symptoms

Gastrointestinal upset (if green parts or unripe fruits are consumed)

usually no action needed

Watermelon flesh (seedless) is safe for budgies in very small amounts as an occasional treat. Seeds, leaves, and stems should be avoided as they may contain potential cucurbitacins. Due to high water and sugar content, offer only in tiny amounts.

Open animal page

Farm animals

Horse icon for animal safety ratingHorse

Flesh

Seeds in large quantities, Rind (if overconsumed)

Risk factors

Overfeeding, Unripe or wild forms with bitter compounds, High sugar content

Symptoms

Gastrointestinal upset, Diarrhea if overconsumed

observe

Watermelon flesh is safe for horses in moderation and can serve as a treat. Due to high water and sugar content, it should only be fed occasionally. Seeds and rind may cause digestive issues if overconsumed. Wild or unripe forms may contain cucurbitacins, which are bitter and can cause gastrointestinal irritation. Seeds should be given only rarely and cooked due to potential intestinal blockage risk.

Open animal page
Chicken icon for animal safety ratingChicken

Flesh

Seeds, Leaves, Stems

Risk factors

Excessive consumption of seeds or leaves, Unripe fruits with higher bitter compound levels

Symptoms

Gastrointestinal upset, Diarrhea, Vomiting

observe

Watermelon flesh is safe for chickens in small amounts as a treat. Seeds may cause gastrointestinal upset if consumed excessively. Leaves and stems contain potentially toxic cucurbitacins and should be avoided. Due to high water content, offer only in small amounts.

Open animal page
Duck icon for animal safety ratingDuck

Flesh

Seeds, Leaves, Stems

Risk factors

Overconsumption of seeds or green parts, Unripe fruits with higher bitter compound levels

Symptoms

Gastrointestinal upset, Diarrhea, Vomiting

observe

Watermelon flesh is suitable for ducks in small amounts as a treat. Seeds, leaves, and stems contain potentially toxic cucurbitacins and should be avoided. Overconsumption can lead to digestive issues. This is a cautious inference from the geese profile and the known plant-part risks.

Open animal page
Goose icon for animal safety ratingGoose

Flesh

Seeds, Leaves, Stems

Risk factors

Overconsumption of seeds or green parts, Unripe fruits with higher bitter compound levels

Symptoms

Gastrointestinal upset, Diarrhea, Vomiting

observe

Watermelon flesh is suitable for geese in small amounts as a treat, but seeds, leaves, and stems contain potentially toxic cucurbitacins and should be avoided. Overconsumption can lead to digestive issues. Young leaves and flowers are rarely used and may be tolerated in very small amounts but are not recommended.

Open animal page
Sheep icon for animal safety ratingSheep

Flesh

Seeds in large quantities, unripe fruits

Risk factors

Excessive seed consumption, Feeding unripe fruits, Individual sensitivity

Symptoms

Gastrointestinal upset, Diarrhea, At high seed quantities: respiratory distress

observe

Watermelon flesh is generally safe for sheep as an occasional treat. Seeds contain low levels of cyanogenic compounds and should only be fed in very limited quantities. Unripe fruits may contain cucurbitacins that can cause gastrointestinal irritation. Sheep should not have access to wild forms or bitter-tasting melons. The high water and sugar content necessitates limited feeding to avoid digestive upset.

Open animal page
Goat icon for animal safety ratingGoat

Flesh

Seeds in large quantities, Unripe fruits

Risk factors

Excessive consumption of seeds, green parts, or unripe fruits., Individual sensitivity.

Symptoms

Gastrointestinal upset (if green parts or unripe fruits are consumed), Diarrhea

observe

Watermelon flesh is suitable for goats in small amounts as a treat. Seeds, green parts, and unripe fruits should be avoided as they may contain potentially harmful cucurbitacins. Overconsumption can lead to digestive issues. This is a cautious inference from the sheep profile and the known plant-part risks.

Open animal page
Cattle icon for animal safety ratingCattle

Flesh

Seeds in large quantities, unripe fruits

Risk factors

Excessive seed consumption, Feeding unripe fruits, Individual sensitivity

Symptoms

Gastrointestinal upset, Diarrhea, At high seed quantities: respiratory distress

observe

Watermelon flesh is safe for cattle in moderation and can serve as a treat. Seeds contain low levels of cyanogenic compounds and should only be fed in very limited quantities. Unripe fruits may contain cucurbitacins that can cause gastrointestinal irritation. The high water and sugar content necessitates limited feeding to avoid digestive upset. This is a cautious inference from the sheep profile and the known…

Open animal page
Pig icon for animal safety ratingPig

Flesh

Seeds in large quantities, unripe fruits

Risk factors

Excessive consumption of seeds, green parts, or unripe fruits., Individual sensitivity.

Symptoms

Gastrointestinal upset (if green parts or unripe fruits are consumed), Diarrhea

observe

Watermelon flesh is suitable for pigs in small amounts as a treat. Seeds, green parts, and unripe fruits should be avoided as they may contain potentially harmful cucurbitacins. Overconsumption can lead to digestive issues. This is a cautious inference from the sheep profile and the known plant-part risks.

Open animal page

These guidelines are for general information only and do not replace veterinary diagnosis. If critical plant parts were ingested or the animal shows unusual behaviour or symptoms, seek veterinary advice.

Max risk

unknown

Highest status

selected parts only

Urgency

observe

Saving seed

watermelon Saving seed

Seed viability

3 - 5 years

Practical tips

watermelon Practical tips

Common beginner mistakes

Sowing or planting outdoors too early, before the risk of frost has passed.Insufficient planting distance, leading to poor air circulation and increased susceptibility to diseases.Inconsistent watering, resulting in splitting or bitter fruits.

Success pattern

Choosing a warm, sunny location and nutrient-rich soil.Consistent watering throughout the growing season.Regular fertilization, especially during fruit development.

High-impact tips

Mulching the soil around the plants helps retain moisture and suppress weeds.Encourage pollinators like bees by planting flowering plants nearby.Choose early-maturing or disease-resistant varieties for a higher success rate.

Plant Profile

Additional plant images

watermelon (Citrullus lanatus): plant portrait - Cucurbits, Gourd family, Harvest August - October
watermelon (Citrullus lanatus): plant portrait - Cucurbits, Gourd family, Harvest August - October
watermelon (Citrullus lanatus): whole plant for plant portrait - Cucurbits, Gourd family, Harvest August - October

Health

Pests, Diseases

Plant health

AphidsSpider mitesCucumber BeetlePowdery mildewDowny mildewRoot rotNitrogen deficiencyPhosphorus deficiencyPotassium deficiencyMagnesium deficiencyFruit rotUnripe fruitsLack of pod formation

Diagnosis help

watermelon Diagnosis help

Pest groups

Sucking pests (aphids, spider mites)Chewing pests (beetles, caterpillars)Boring pests (larvae)

Disease groups

Fungal diseases (mildew, rot)Bacterial diseases (wilt)

Prevention

Site selection: Sunny, warm, sheltered from wind.Soil preparation: Nutrient-rich, well-draining.Variety selection: Disease-resistant, adapted to climate.Plant spacing: Adequate for air circulation.Watering: Consistent, at the root collar, avoid waterlogging.Fertilization: Balanced, needs-based.Crop rotation: At least 3-4 years break between cucurbits.Hygiene: Remove infected plant parts and fruits.Encouraging beneficials: Create habitats, use beneficial insects.

Diagnosis

Accurate diagnosis of problems often requires observing symptoms on leaves, stems, and fruits, as well as considering cultivation conditions. When in doubt, it is advisable to consult specialized literature or experts.

Cultural prevention

Choose a sunny, warm, and sheltered location.Improve the soil with compost and ensure good drainage.Maintain sufficient plant spacing for good air circulation.Choose disease-resistant varieties.Practice consistent crop rotation (at least a 3-4 year break).Avoid waterlogging and excessive leaf wetness, especially overnight.Encourage beneficial insects by creating habitats and avoiding insecticides.

Monitoring

Regularly inspect plants for signs of pests and diseases.Pay particular attention to leaf undersides and young shoots.Check soil moisture and adjust watering.Monitor the weather and adjust preventive measures (for example protection during rain).

First response

At the first signs of aphids: hand-pick, rinse with water, or use potassium soap.At the first signs of spider mites: rinse plants and use neem oil.At the first signs of mildew: plant teas (horsetail) or a baking soda solution.If beetle-related wilt is suspected: collect beetles and use crop protection netting.

Diagnostic rules

White, powdery coating on leaves

Possible causes: Echter mehltau cucurbitaceen

  • Witterung (warm, feucht)
  • Luftzirkulation

Yellowish spots on leaves, grayish-blue coating on leaf underside

Possible causes: Falscher mehltau cucurbitaceen

  • Weather conditions (cool, humid)
  • leaf wetness overnight

Rapid wilting of vines or entire plant, even with moist soil

Possible causes: Bakterielle welke cucurbitaceen, Wurzelfaeule cucurbitaceen

  • pest infestation (cucumber beetles)
  • soil moisture and drainage
  • cut through the stem (bacterial ooze test)

Wilting, stunted growth, mushy roots

Possible causes: Wurzelfaeule cucurbitaceen

  • soil moisture and drainage
  • Wurzeluntersuchung

FAQ

When is the best time to sow watermelons?

Sowing indoors is done about 4-6 weeks before the last frost, typically in March or April. Direct sowing outdoors is only possible from mid-May onwards, when the soil has reached at least 15°C.

How much space do watermelons need in the garden?

Watermelons are vigorous growers and require ample space. Plan for about 1 to 1.5 meters of space in all directions per plant to ensure good air circulation and prevent diseases.

How do I know if my watermelon is ripe?

Ripe watermelons sound dull and hollow when tapped. The tendril attachment, where the fruit hangs from the stem, becomes dry and woody. The underside of the fruit also changes color from whitish to yellowish.

Can watermelons be grown in containers?

Due to their vigorous growth and space requirements, watermelons are generally unsuitable for container cultivation. However, some dwarf varieties might be suitable for larger containers, but yields are often lower.

Why are my watermelons splitting?

Fruit splitting is usually caused by uneven watering. If the plant receives a sudden influx of water after a dry spell, the fruit can split. Ensure consistent soil moisture.

Is watermelon safe for Dog?

watermelon is classified as selected parts only for Dog. Risk: unknown. Urgency: usually no action needed. Watermelon flesh is safe for dogs in moderation and is commonly used as a treat. Seeds should be removed as they pose a choking hazard, although they are not toxic. The white rind between the flesh and hard shell is edible but often tough and tasteless, thus not recommended.

Is watermelon safe for Cat?

watermelon is classified as selected parts only for Cat. Risk: unknown. Urgency: usually no action needed. Watermelon flesh is safe for cats in moderation and can be given as an occasional treat. Seeds and rind should be avoided as they are difficult to digest and may pose a choking hazard. Cats are obligate carnivores, so plant matter should only be offered in very small quantities.

Is watermelon safe for Rabbit?

watermelon is classified as selected parts only for Rabbit. Risk: unknown. Urgency: observe. Watermelon flesh is suitable for rabbits in small amounts as an occasional treat. Seeds, leaves, and stems contain potentially harmful cucurbitacins and should be avoided. Due to high water and sugar content, feed only occasionally.

Is watermelon safe for Guinea pig?

watermelon is classified as selected parts only for Guinea pig. Risk: unknown. Urgency: observe. Watermelon flesh is suitable for guinea pigs in small amounts as an occasional treat. Seeds, rind, leaves, and stems should be avoided as they may contain potentially harmful cucurbitacins. Due to high water and sugar content, feed only occasionally.

Guides

Related guides

Garden guides

Sources

Public sources

  1. Wikidata entity

    Wikidata · 2026-05-15

  2. GBIF species match

    GBIF · 2026-05-15

  3. Deutschsprachige Wikipedia: Wassermelone

    Wikipedia · 2026-05-15

  4. English Wikipedia: Watermelon

    Wikipedia · 2026-05-15

  5. Trefle API: Citrullus lanatus

    Trefle · 2026-05-15

  6. Perenual API: Citrullus lanatus

    Perenual · 2026-05-15

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