Watermelon, that sweet and juicy fruit, is a staple during South African summers. You can enjoy it all on its own or find it in all sorts of treats, from smoothies to salads and drinks. But this fruit isn’t just for eating; it’s also your health-boosting cousin!
Watermelons are typically consumed as fresh fruit, but it can also be used in a variety of culinary applications.
Mandisa Mazibuko, an agronomist from Mafikeng, North West, says watermelon is packed with nutrients such as lycopene, citrulline, and vitamins A and C. It also has a high-water content, which helps with hydration.
She explains that the antioxidants and amino acids in watermelon can support exercise performance and may even reduce tumour growth by helping cancer cells break down.
“The citrulline increases nitric oxide levels in the human body which helps the blood vessels expand and lowers blood pressure.”
Agronomist Mandisa Mazibuko
Watermelon is also rich in minerals like magnesium and potassium, which help with bone and heart health. Vitamin A and C, both found in watermelon, are important for healthy skin, and vitamin C helps the body produce collagen, which is key for strong hair, she adds.
Varieties in Mzansi
According to Nangamso Mtamzeli-Cekiso, a horticultural scientist at Dohne Agricultural Development Institute in Stutterheim in the Eastern Cape, watermelon comes in different varieties. Cultivars in Mzansi include the Crimson Sweet, Sweet Princess, Charleston Grey, triploid seedless, and Congo.
Watermelon is native to tropical Africa and Mtamzeli-Cekiso explains that watermelon is drought-tolerant and can be used as a source of drinking water in water-scarce areas.
The plant’s vines send out runners that grow along the ground, providing a natural support system. Its tendrils wrap around objects to help the plant stand upright.
Sowing time and climatic requirements
Watermelons are typically grown by direct sowing and are not frost-resistant.
They may be planted from early spring to mid-summer (September to January) in frost-free locations, says Mtamzeli-Cekiso.
“In frost-occurring areas, sowing should be done after the last frost has passed or between late October and mid-December.”
Horticulturalist Nangamso Mtamzeli-Cekiso
To ensure uniform germination, the soil temperature for watermelon seeds should be at least 180 C. She also recommends planting the seeds about 2cm deep into the soil.
It’s important to consider the ideal temperature range for maximum yields – between 220C and 320C during the day and not lower than 180C or higher than 350C at night. Temperatures outside of this range can cause problems with plant growth and crop maturity, she adds.
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Soil requirements and harvesting
Watermelons can be grown in a variety of soils, although sandy loamy soils produce the highest yields. Avoid clay soils since they lack adequate drainage and aeration for watermelon development, advises Mtamzeli-Cekiso.
“Soils with a pH of 5.8 to 6.8 can be used to grow these crops. Soil temperatures above 1800C are required for uniform seed germination. Saline soils should be avoided for watermelon production.”
Watermelons develop in about 90 to 110 days, depending on the variety. She highlights the need to harvest at the proper time because late harvesting leads the fruit to be overripe, resulting in lesser shelf life.
On the contrary, once an unripe watermelon is harvested, it will not continue to ripen. However, determining whether or not watermelons are ripe might be difficult.
There are several approaches for determining the harvest ripeness of watermelons, for example, thumbing, noting appearance colour changes, observing drying of the stem tendril. Growers also taste the fruit to ensure that it is safe to eat.
Mtamzeli-Cekiso recommends testing maturity with a refractometer – a 9% (brix) value indicates maturity.
Effective health prevention and management
In addition to all the other nutrients in watermelon, it also contains lycopene, an antioxidant that may reduce the risk of heart disease and stroke, says Mazibuko.
Watermelon extract has been found to lower blood pressure over time. It also contains two amino acids – L-citrulline and L-arginine – that may improve the function of blood vessels, she explains.
“The lycopene can also reduce risks of cancer as it reduces inflammation, imbalance between free radicals and growth of cancer-causing cells.”
She adds that the research has shown that watermelon may help reduce the risk of prostate and digestive tract cancer. The vitamin A in watermelon also helps keep skin healthy and moisturised, preventing dryness and flakiness. Additionally, the minerals in watermelon like potassium can help keep skin hydrated and elastic.
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