Summer brings the arrival of one of our garden favorites - watermelon. One of the primary challenges to eating watermelon can be those pesky seeds. We don’t want to eat them because, you know, a watermelon will grow in your belly (just kidding). Or, we embrace our inner child and consider seed spitting as a recreational activity, and there’s nothing wrong with that.

Seedless watermelons can overcome this challenge. But how in the world do they grow watermelons without seeds, since this is the whole reason plants produce fruits? Here’s how that works.

While seedless watermelons have been around for about 50 years, they are considered a newcomer as far as fruits and vegetables go. The good thing is that, the seedless watermelons of today are just as sweet and flavorful as the watermelons with seeds, which wasn’t always the case.

Seedless watermelons may be a bit of a misnomer though. They actually have seeds, they are just immature, white, edible seeds as compared to the black, hard, crunchy seeds we find in standard watermelons. Although, you can still find a black, hard seed in seedless watermelons on occasion.

Seedless watermelons come into existence through creative crossbreeding, and a little bit of science. Here’s the deal.

A standard watermelon has 22 chromosomes which is called a diploid. The “di” in diploid means “two” as in dissect. So, when you have a watermelon with 22 chromosomes, cell division happens in the standard way with the plant producing eggs and pollen that each contain 11 chromosomes. When combined, you get the standard 22 chromosome watermelon.

Through the use of a chemical process, the number of chromosomes can be doubled from the standard 22 to 44 which is called a tetraploid with “tetra” meaning four. When the pollen from a plant with 22 chromosomes comes in contact with the female flower on a plant with 44 chromosomes, the resulting seeds have 33 chromosomes which is known as a triploid with “tri” meaning three.

Triploid watermelon plants produce flowers, but their pollen tends to be sterile. However, if you pollinate a triploid watermelon plant with pollen from a diploid plant, you get a watermelon that is essentially, without seeds. As far as seedless watermelon varieties go, the OSU Extension recommends King of Hearts or Tri-X 313 for our area.

Because of this, when you plant seedless watermelon seeds, you need to plant some seeded watermelon seeds also since you will need them for pollination. When purchasing seedless watermelon seeds, make sure either your supplier includes standard watermelon seeds, or you’ll need to purchase these also. In addition, seedless watermelon seeds tend to be more expensive than standard seeds. It just depends on how badly you want to grow your own seedless watermelons. Good luck!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org.Photo: OSU Ag. Comm.