Growing watermelon: expert tips for cultivation

Growing watermelon: expert tips for cultivation

No other fruit is more refreshing on a hot summer day than the watermelon. With these tips you can grow watermelon in the comfort of your own garden.

Watermelons (Citrullus lanatus) are exotic fruits that are mostly imported to our local supermarkets from distant countries. In fact, the green-skinned and pink-fleshed fruit is native to West Africa. Therefore, the delicious fruits grow and feel the best in warm temperatures. Despite watermelon’s climate preferences, with the right tips and tricks it is possible to cultivate it in milder latitudes. This is an overview of how to grow watermelons in the home garden.

Planting watermelons: when, where and how

Although watermelon belongs to the gourd family (Cucurbitaceae) together with pumpkins, cucumbers and courgettes, the watermelon is more sensitive to cold than its relatives. For this reason, it is important to choose the right location and time to plant watermelons.

Where to plant watermelons

Watermelon plants have specific soil requirements. The following is essential: watermelons prefer a sandy and humus soil. Soils that are too heavy hinder root penetration and tend to accumulate water. We also recommend preparing the garden bed with a lot of compost before planting so that the watermelon plant gets enough nutrients. In addition to the right soil, a warm, sunny and wind-protected place is ideal to grow melons. For example, the perfect location to cultivate melons is by a south wall of the house or in the greenhouse.

Tips for the right location:

  • Light and humus soil (heavy soils are not suitable)
  • Warm, sunny and wind-protected place
  • Optimally in a greenhouse or by a south wall

When to plant watermelons

Watermelons are plants that require warmth – planting them outside too early can therefore be fatal for the vulnerable plants! It is best to plant young plants outdoors earliest at the end of May. In the greenhouse you can start as early as April. Temperatures below 12°C can damage the development of the watermelon plants.

How to plant watermelons

The actual planting out of the exotic is relatively simple: place the young plants in the bed at a sufficient distance. Always calculate 1 to 2 square metres per plant so that it has enough space to grow.

Planting watermelons in a pot

A good alternative to growing melons in the bed is planting them out in a pot. In this way, you save space in the bed and still don’t have to do without the delicious fruit. When growing watermelons in a pot, you should be aware that the soil warms up faster than in the open, but it also dries out quicker. Therefore, choose a pot that is as large as possible and water it frequently. It is best not to place the plant in the blazing sun, as the soil dries out more quickly there and the risk of damage by drought increases.

Growing watermelons: buying or reproducing them yourself?

Before you start growing watermelons in spring, many people ask themselves the question: is it better to buy a watermelon plant or reproduce it at home from seeds? Here, both options are discussed and the advantages and disadvantages are explained.

Reproducing watermelons at home

Reproducing own watermelon plants is quite unproblematic and the germination rate is high. From March to April, insert one seed per growing pot at a depth of about 1 to 2 cm. A temperature of over 18°C is necessary for germination, ideally 22 to 24°C. A windowsill is a very good place for cultivation and the first seedlings can be seen after 5 to 10 days. As soon as the first leaves appear, the young plants can be rehomed into larger pots. When repotting, make sure that the roots are not damaged, as watermelons are very sensitive to injuries.

Instructions for reproducing watermelons at home:

  • Sowing from March – April at a depth of 1 – 2 cm
  • Position on windowsill or in mini greenhouse (min. 18°C)
  • The first seedlings appear after 5 – 10 days
  • Move into larger pots as soon as first leaves appear

Buying watermelon plants

It is of course easier to purchase young watermelon plants in stores. You can buy these in garden centres from May to June and then plant them out in the open. One advantage of these young plants is that they are often grafted on pumpkins and are therefore less susceptible to root diseases. The choice is really up to you and how much money you are willing to pay, because the plants bought in stores in larger quantities are of course considerably more expensive than watermelon seeds.

Watermelon species and varieties

Many people have a specific look of the watermelon associated with this fruit: green with a pink flesh. In reality, watermelons are very diverse. The varieties differ from each other in appearance, but they are all Citrullus lanatus. Two varieties of watermelon can be distinguished:

1. Citrullus lanatus var. lanatus: The cultivated watermelons, which are cultivated commercially worldwide, belong to this variation. This is the classic watermelon that everyone knows and loves.

2. Citrullus lanatus var. citroides: This wild form of melon grows mainly in Africa and is also known as tsamma melon. The flesh of this variation is not pink, but yellowish to light green.

The varieties for cultivation in Europe belong mainly to the variation Citrullus lanatus var. lanatus. Some of them can also grow in the cooler climates.

These are some of the most popular watermelon varieties; a more extensive list of watermelon varieties can be found here.

  • Bush Sugar Baby
    • New variety derived from the variety Sugar Baby
    • Early ripening with smaller fruits: 2 – 4 kg (1 – 2 fruits per plant)
    • Red flesh with dark skin
    • Plant remains quite compact (1 m² per plant)
  • Crimson Sweet
    • Spread worldwide and popular
    • Oval and light green fruits; high fruit weight: 5 – 8 kg
    • Aromatic light red fruit flesh
    • Good resistance to leaf rot and other fungal diseases
    • 1,5 – 2 m² per plant
  • Red Star
    • Dark skin and deep red flesh; high sugar content
    • Fruit size: 6 – 8kg
    • The variety is suitable for cultivation in temperate climates and should not be cultivated in rough areas due to the slightly longer ripening period
    • 1,5 m² per plant

Growing watermelons: the proper care

As soon as the watermelon plant has become well accustomed to its position in the garden, it will accelerate its growth. A few instructions should be followed to ensure that the plant is sufficiently supplied with water and nutrients.

watermelon in the garden
You can harvest watermelons once they are fully ripe [Shutterstock.com/ TOONGNA ONLINE]

Watering watermelons properly

Watermelons have a high water requirement – not surprising when you look at the juicy flesh. It is therefore of utmost importance to water the plants sufficiently in summer. The soil should be watered daily, preferably every morning, especially during fruit formation. Make sure you only use temperate water, as the plant does not tolerate cold water well. For example, you can use water from the rain barrel. When watering, be careful not to wet the leaves as this increases the risk of infection with powdery mildew.

Fertilising watermelons

Watermelons are regarded as heavy feeders in the garden – a good supply of nutrients is therefore vital. Before planting, it is advisable to work compost into the bed. In the further course of summer, you should fertilise every two weeks in order to provide sufficient nutrients. Natural fertilisers or organic materials such as horse manure work well.

Harvesting watermelons: how to tell if they are ripe?

The ripening period of watermelons is comparatively long – the large fruits are only harvested from the end of August into autumn. In order to have the best tasting fruit, it is important to harvest only the ripe fruit. Watermelons develop their sweet taste over time as they grow on the mother plant. In order to see whether a watermelon is ripe and ready for harvest, you should pay attention to these signs:

  • Dark green skin with yellowish spots
  • Dull sound when you knock on it
  • Withering leaves in autumn

Storing watermelons

The shelf life of watermelons is relatively limited and they should be best consumed quickly. At room temperature, the exotic fruit can be stored uncut for two weeks. As soon as it is cut, its shelf life unfortunately shortens very quickly and the fruit should therefore be stored in the refrigerator. Freezing watermelons, on the other hand, is not recommended, as the fruit consists mainly of water and its consistency worsens after thawing. You can find out more about harvesting and storing watermelons properly here.



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