The 'fruit' of summer — watermelon

By Lynette L. Walther | Jul 22, 2020
Photo by: Lynette L. Walther One of summer’s sweet rewards is watermelon, and growing your own is even sweeter.

Not really a fruit, but rather a melon as its name implies, watermelons are the very essence of summer wrapped up into one big ball of cool refreshment. For the first time, I am attempting to grow watermelons this year.

According to the National Garden Bureau (NGB) watermelon can be done successfully in all parts of the country. Here in Maine, where hot days may not be long enough, choose an earlier-to-mature variety like AAS Winners ‘Shiny Boy,' ‘Golden Crown,' or ‘Yellow Baby’ that all mature in 70-75 days.

For a smaller variety that will fit in the refrigerator easily, try one of these newer ice-box AAS Winners like ‘Mini Love,’ ‘Cal Sweet Bush,’ ‘Gold in Gold,’ or ‘Mambo.’

Heirloom fans will want to plant that perennial Maine favorite ‘Moon and Stars,’ introduced in 1926, with a deep green skin speckled with tiny yellow stars and quarter-size moons.

If watermelons are part of your garden plans this summer, here are NGB watermelon breeder members answers to the top 10 most-asked questions on growing watermelons:

What soil temperature is best for growing watermelons?

It is recommended that soil temperatures be 70 degrees Fahrenheit or above for seeding or transplanting watermelons. In a cooler climate, consider applying a plastic mulch before seeding or transplanting melons. This helps warm the soil during cool nights, control weeds and help with uniform irrigation.

What are the major pests to watch for and how do you organically prevent them?

Surprisingly there are actually very few insect pests for melons and watermelons. The plants have many pubescence (hairs) that act as natural protection against pests. Crawling insects like flea and cucumber beetles can be controlled by floating row covers, diatomaceous earth, and organic insecticide soap applications.

Does watermelon need more water than typical fruiting plants (such as tomatoes) because the fruit is so large and mainly water?

These desert-inspired plants are actually very adapted at storing water. The fruits are indeed mainly water and a wondrous storage vessel for needed moisture in the dry climates.

Since watermelons have survived in arid climates for centuries, they are well adapted at growing in minimal water conditions. Too much water is much more detrimental to watermelons than too little. Over irrigation creates root pathogens that are difficult to control.

At later stages, too much water can split fruit, apply minimal irrigation after fruits begin to ripen. Water in short intervals and do not let irrigation come into contract with the crown of the plant.

How long are most melon seeds viable if properly stored?

If properly stored at the optimal recommended rates: below 60 degrees Fahrenheit and 30 percent humidity, melon seeds can be viable for many years. A common rule of thumb for seed storage is that the temperature (in Fahrenheit) plus the relative humidity in the air (in percent) should total less than 100 for satisfactory seed storage.

Remember humidity is the real killer when considering seed storage. Seeds are quite happy to be stored in any dark, dry, and cool location for many years. As the seed is stored and ages, the germination, and vigor are reduced.

Any way to sweeten a watermelon or does it naturally grow like that?

Watermelons have naturally high levels of sweetness/sugars. One way to enhance the sweetness of your watermelon is to reduce the irrigation during the ripening stage. Sweetness can also be related to genetics; some varieties are recorded to have higher sugar levels when tested.

Do watermelon plants need nitrogen?

Watermelons are not heavy nitrogen feeders, actually, too much nitrogen can create excessive vine growth and less fruit set. A well balanced 15-15-15 or 10-10-10 fertilizer works great in a garden setting.

How much space does a growing watermelon plant need? Are there varieties for small spaces?

Watermelon can be grown easily in smaller garden areas with bush varieties. Try seeding a watermelon variety like Cal Sweet Bush, Mini Love, or Sugar Baby Bush in your smaller garden.

The vines only reach 18 to 20 inches instead of 3 plus feet. Plant bush watermelon in hills of two plants about 12 to 14 inches apart. You should be able to grow one nice watermelon on every bush plant.

Also, consider growing your standard vining watermelon vertical, train your large vines up like runner beans. Do not forget to support the fruits with a hammock as they grow.

What do I need to know about the blooms and pollination?

Watermelon vines produce both male and female flowers. Bees are necessary for pollination, as is the timing, meaning both male and female flowers need to be open at the same time. Sometimes, there may not be a pollinator present, in which case, the plant can be hand pollinated.

I get opinions that are all over the place when talking about when to pick a properly ripened melon.

There are many wives’ tales about picking the perfect summer melon. One of the easiest ways to tell if a watermelon is mature is by looking at the small leaf (pig’s ear) next to the curly tendril at the stem end of a watermelon. If the pig’s ear and tail are dry or almost dry, the watermelon is ready to eat.

How are seedless watermelons created?

Seedless watermelons are a hybrid that creates a genetic dead end. Both the parent lines have seeds, when they are crossed the progeny is seedless or triploid.

What happens when you cross a horse and donkey? You get a mule. A mule is sterile and cannot reproduce, just like seedless watermelon. You have to grow a pollinator or seeded watermelon next to a triploid to even set fruits. Seedless watermelons can have undeveloped white seed coats inside the flesh, but even a fully colored dark seed coat has no embryo.

Lynette L. Walther is the GardenComm Gold medal winner for writing and a five-time recipient of the GardenComm Silver Medal of Achievement and the National Garden Bureau’s Exemplary Journalism Award. Her gardens are in Camden.

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