Heart Shaped Watermelon in Japan

Square Pumpkin Project

Toward the end of summer in 2014, a customer inquired about shaping pumpkins for the fall season.  We’ve had
several customers order our molds for this purpose, but we have never received any feedback on the success
or failure of the venture.  Below you’ll find pictures with brief exerts of advice that our customer sent us
to share for anyone interested in attempting the process themselves.  The pumpkins were a big hit for Halloween.


Above, a pumpkin takes the shape of a heart mold.  In humid areas, condensation will appear inside where the pumpkin
hasn’t reached the mold. This is normal. The pumpkin can tolerate the moisture and excessive moisture or water will
drain through the holes in the mold.


A pumpkin begins to ripen inside a square or cubed shaped mold. When pumpkins are first placed inside the mold
they are a pure green color. When they’re approaching the end of the growing process, they will fade from green
into the pumpkin orange color associated with pumpkins.


A mold just recently placed on a pumpkin. This pumpkin is an optimal size for a mold. Because pumpkins all grow different
sized based on a number of variables (rainfall, temperature, sunlight, nutrients, etc), the a “good candidate” for a mold
is a completely green pumpkin that can barely fit inside a closed mold. This is the safest indicator that your pumpkin
will grow large enough to fill out the inside of the mold.


As mentioned above, after rainfall and in high humidity areas, the mold will collect moisture. Fortunately pumpkins are
resilient and can withstand the moisture. Excess condensation will drain out through the holes designed on the mold.
Once the pumpkin begins filling out the mold, moisture will have less and less of an opportunity to appear, until the
fruit is fully formed and ready to be taken out of the mold.

pumpkinboxinfield2 pumpkinboxinfield heartinfiled2 heartinfiled

All of our molds come with nuts and bolts to seal every hole on the mold, but after many growing seasons, some growers
have replaced the nuts and bolts with zip ties. Plastic zip ties will work fine so long as they are used on every hole.
Leaving some holes vacant will cause the pressure of the growing melon to apply disproportionately to mold, which in
some cases can cause the mold to break.


Each mold comes with enough nuts and bolts to secure every hole on the mold and it is very important that you do this.
Leaving a hole empty distributes the pressure of the growing fruit unevenly on the mold. If too much pressure is applied
to a small part of the mold, the mold can crack as seen above.


Once your pumpkin has begun to turn ripen or turn orange, its ready to be picked. You’ll see that the fruit has taken
the shape of the mold. The pumpkin will be very secure and tight in the mold, so it make take some effort to free it.
Using the stem to wiggle it will help loosen it. Once its loose, the pumpkin will come out with ease.

boxinhand pumpkin1 heartinhand

A History of Shaping Fruits

Shaping fruit is a centuries old practice.  While originated in China, contemporary fruit molding has been honed among Japanese farmers seeking a competitive advantage by making their watermelon cheaper to ship and store using a cube or square shape.  We buyers saw watermelon in the shape of a cube, the first sentiment was disbelief.  Once customers were shown that the watermelon were real, a new niche market of shaped watermelon that sell for several hundred dollars was born. Unlike in the West, watermelon play a unique role in Japanese culture.

square watermelon sorted

Japanese square watermelon being sorted by farmers prior to shipping.

Cubed watermelon on display in Japan with custom writing.  Every summer, Japanese citizens throughout the country and especially near the coast will participate in a game called Suikawari.  Similar to a pinata in Mexican culture, participants will try to break a watermelon open using a bat while blindfolded.  Watermelon rest at the center of this unique cultural event.



Farmers in Japan in awe over a watermelon being shaped into a cube.

Fruit molding or shaping isn’t exclusive to watermelon! Below a zucchini takes the shape of 20oz drink by inserting the growing fruit into a clear bottle. Very cool!

308149709-2 blossomspot


Using plaster molds, gourds are shaped into three dimensional portraits.  This method is often cited as the original for shaping fruit.  Gourds were shaped by Mr. Zhang Cairi as detailed in The Immortal Molded Gourds of Mr. Zhang Cairi. Learn more here!


A Mickey Mouse shaped pumpkin grown at Epcot Center in Orlando, Florida.


Big money premiums for Square Watermelon.



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