How to Grow Organic Watermelons

Today, we will see how to cultivate watermelons in our organic garden. Watermelon, also known as cantaloupe or watermelon, is one of the iconic fruits of the summer season. It is loved by everyone for its sweet sugary taste and refreshing properties. Those with some space in their garden can cultivate a few watermelon plants and enjoy great satisfaction. The key is to understand the characteristics of the plant, the different varieties, and the proper cultivation techniques.

In this article, we will explore various aspects of home cultivation using only organic techniques.

Origin and Spread of Watermelon

Watermelon, scientifically known as Citrullus lanatus, belongs to the botanical family Cucurbitaceae, just like zucchinis and cucumbers.
This cultivar has its origin in tropical Africa. Its cultivation was widespread 5000 years ago in ancient Egyptian civilization. Watermelon was placed in the tombs of pharaohs as food for their journey to the afterlife.
Subsequently, the cultivation spread to China, which remains the world’s leading producer, while it arrived in Europe only in the 13th century, following Arab invasions.
Currently, watermelon cultivation is a widespread practice worldwide.

Botanical Characteristics of the Watermelon Plant

Watermelon is an herbaceous plant with an annual cycle, consisting of a main stem or trunk. It branches into other trailing stems on the ground, which can reach several meters in length. The stems are equipped with tendrils that help anchor the plant to the ground.

Roots

The watermelon plant has a well-developed root system, especially in the superficial part of the soil. Although it is superficial, the roots can reach good depths.

Leaves

The leaves are large and lobed, deeply incised or lobed, with a color that varies from dark green to light green.

Flowering

Watermelon is a monoecious plant, meaning it has separate male and female flowers. In the plant’s life cycle, male flowers appear first and outnumber female flowers.
Pollination is entomophilous, meaning it occurs through bees and other pollinating insects. Thanks to the characteristics of the flowers, fertilization occurs through cross-pollination between gametes of different flowers.
Following fertilization, the fruits ripen after about two months.

Fruit and Seeds

The fruit is typical of the Cucurbitaceae family, a large fleshy pepo in which the epicarp, mesocarp, and endocarp are united.
In watermelon, we distinguish the rind, which is green with stripes, smooth surface, and leathery consistency. Inside, we have the pulp, typically red, containing numerous black, flattened seeds.
The size, weight, and shape vary greatly depending on the cultivated variety. For example, they can be spherical or oval in shape. The weight ranges from 2 kg for “mini” varieties to 15 kg and more for local varieties.

Varieties

Different watermelon varieties are distinguished primarily by the origin of the seed. As watermelon seeds are easy to preserve and reproduce independently, many local varieties have been established over time, with regional characteristics.

Round Fruit Varieties

Among the most well-known varieties, we have the watermelons “milanese”, “romagnolo”, “comacchiese”, “calabrese” and “napoletano”. These are all varieties with round-shaped fruits, not very large, weighing between 3 to 7 kg. The rind is dark green or very dark, and the pulp is bright red, sweet, and sugary. These varieties are very hardy and easy to cultivate, adapting well to difficult soils.
If you want to cultivate watermelons in your home garden, we recommend searching for seeds of these local varieties at seed exchange fairs. Unfortunately, market demands have led to the development of hybrid seeds, which have become popular due to their high productivity.
Among the hybrid round and small-sized varieties, we have the famous sugar baby watermelon of American origin, known for its exceptional sweetness.

Hybrid Varieties with Oblong Fruits

Most hybrid watermelon varieties with oblong fruits are of American origin. They produce very large fruits, more or less oval in shape, weighing between 9 to 20 kg.
The color of the rind varies from light green, almost grayish, in varieties like Irish grey and Charleston grey, to bright green with light patches in varieties like Klondiche, Crimson sweet, and Fairfax. There are also varieties with very intense dark green to black rinds, like Congo and Diamante nero.
As mentioned earlier, these are very productive varieties, characterized by very sweet flesh. However, they require specific soil and cultural care.

How to Cultivate Watermelons

Climate Requirements and Sowing Period

Watermelon cultivation requires a mild climate throughout its biological cycle, as it originates from Africa. For this reason, it is cultivated in gardens from late spring (between the months of April and May) until the end of summer.
To germinate, the seed requires a minimum temperature of 15 °C. The ideal vegetative growth occurs with temperatures between 25 and 35 °C. Sudden cold spells during the spring, with temperatures dropping below 10 °C, can compromise the plant’s vital functions and, consequently, the success of the harvest.

Soil and Fertilization

The ideal soil for watermelon cultivation is loose and deeply worked. Therefore, it is essential to prepare the soil before sowing.
It is advisable to avoid clayey soils, as they can cause water stagnation, which the cultivar does not tolerate well.
The soil should also have a good supply of organic matter. For optimal organic fertilization, it is recommended to cover the soil with mature animal manure during the winter months. This should be worked into the soil before cultivation begins. If you do not have manure from organic farms, you can use dry stall manure. This should be added to the soil about 15 days before planting. It is an excellent solution, and the product is easily available.
Another solution for a base fertilization is the addition of home compost to the soil.

Direct Sowing and Distances

Watermelon seeds, whether purchased or preserved from previous crops, have excellent germination capacity. As their growth rate is high, direct sowing is usually practiced.
In specific terms, small holes are made where 3-4 seeds are placed at a depth of 2 cm. This is to ensure that two seedlings remain per hole after the seeds have sprouted. It is crucial to maintain proper distances during sowing.
As we have seen, watermelons have a trailing growth habit and tend to spread out extensively in the field. Therefore, an ideal distance between rows is 2 meters, and between holes on a row is 1.5 meters. These distances can increase or decrease depending on the chosen variety. So, pay attention to the type of watermelon you choose to cultivate.

Cultural Care and Irrigation

Ensuring a balanced water supply is essential for successful watermelon cultivation. In the initial phase, water is needed to facilitate seed germination. During vegetative development, water helps to have healthy and vigorous plants. Of course, always be careful not to cause waterlogging. Therefore, using a drip irrigation system ensures balanced water distribution.
Watering is reduced in the final stage of ripening. This helps enhance the sugar content of the fruit.

Mulching

Watermelon cultivation requires numerous hoeing sessions due to its medium-to-long growth cycle. If you want to save yourself from this type of operation, applying a layer of natural mulch is highly recommended.
The plant will benefit in several ways from this agricultural technique. Firstly, it protects against weed infestation. Secondly, it improves soil moisture, thus saving water. Finally, it prevents the fruits from coming into direct contact with the wet ground, avoiding the risk of spoiling the final crop’s quality.

Apical Pruning, Ripening, and Harvesting

Another operation performed on the watermelon plant is apical pruning. This is done when the plant has already extended its branches. This pruning promotes the emission of more productive lateral shoots. Additionally, it prevents excessive lengthening of the plant, favoring lateral growth. In general, it is better to have a few but good fruits rather than many watermelons that do not fully develop. Typically, a plant should not bear more than 4-5 fully mature fruits.
Harvesting usually takes place after 4 months from sowing, during the peak of summer. It is essential to pick watermelons at the right stage of ripeness. To determine the proper time for harvest, carefully observe the fruits and the plant. The most evident signs are: the drying of the stem to which the fruit is attached and a dull, hollow sound when you tap the fruit with your hands. Another tip for achieving even ripening is to periodically turn the fruit to the right and left. This ensures exposure to sunlight on all sides. However, be gentle while doing this to avoid prematurely detaching the immature watermelon.

Biological Pest and Disease Control

In watermelon cultivation, biological pest and fungal disease control is relatively straightforward. This is because watermelon is a very robust plant. Avoiding water stagnation protects against the most risky fungal diseases, such as downy mildew and powdery mildew.
As for harmful insects, attention should be paid to aphids in the early stages of cultivation. However, with the use of macerates and natural preparations, such as the nettle macerate and garlic macerate, we can effectively protect the plants from these annoying insect pests.

Uses and Nutritional Properties

Watermelon is one of the most beloved fruits of the summer season and it is composed of 95% water. Due to this characteristic, it is perfect for those looking to follow a low-calorie diet and remain refreshed on a hot day. But it is also enjoyable for anyone who wants to cool down with a tasty fruit salad.
Another nutritional feature is its high content of soluble sugars (good sugars), such as fructose (along with minerals like potassium and vitamins like C and A).
You can find out more about the nutritional values of watermelon here.

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