You may have heard about mini “personal” watermelons, or seen them in a grocery store. This latest produce craze is a small round watermelon, about the size of a cantaloupe, and weighing 3 to 6 pounds. The mini watermelons have thin rinds and high Brix, meaning they are very sweet.

The most famous of these minis is PureHeart, which Syngenta introduced last year with a major public relations campaign. PureHeart was featured by the Oprah Winfrey Show, Good Morning America, The New York Times, USA Today and Good Housekeeping magazine. It was the subject of an Associated Press story, which went to newspapers all over America. The melons were heralded as being perfect for a small family or a single, great to take along for lunch, and easy to carry. I recently spotted a display labeled “PureHeart” at my local Target, so I paid $3.49 for the little thing and brought it home. Although it was not as small as some of the publicity about mini watermelons had led me to expect (“the size of a grapefruit” was a common description), it was very sweet, with firm red flesh and a thin rind. A fourth of it was definitely enough for one serving.

The 2003 PureHeart crop sold out, and sales figures for this year are estimated at $50 million.

Perhaps you’d like to get in on some of this lucre. Be forewarned that mini watermelon seeds are hard to come by, and they’re expensive. The PureHeart variety is not available at all, as it is sold only to select growers with exclusive licensing agreements. There are several other varieties of mini watermelons, however. Some of the variety names you may encounter are Para Uno, Solitaire, Extazy, Demi Sweet, Mini Seedless 618, Liliput and several varieties that go by numbers such as 5109 and 5130.

Robert Brown, sales and marketing manager for Golden Valley Seeds, said that his company had sold out of seed for one of the mini watermelon varieties it sells, Para Uno, and had a dwindling supply of the other, Solitaire. “Mini watermelons are taking off,” he said. “We can’t produce enough seed to meet demand. We’re limited by the amount of parent stock seed to produce the hybrid.”

Seed was still available in mid-May, though. We located several suppliers that listed mini watermelons on their web sites or in their 2004 catalogs. There are undoubtedly other suppliers, and your best bet is to call your regular seed supplier and ask about availability.
Seedway (800-952-7333) had Solitaire seed at $32.50 for 100 seeds or $243.50 for 1,000 seeds. Siegers Seed (800-962-4999) has Demi Sweet, Extazy, 5109 and 5130, sold in packages of 1,000 seeds.

The planting rate for mini watermelons is 4,200 seeds per acre, Brown said. Beyond that, there is still much work to be done to develop production recommendations. “There has been a complete learning curve for everybody in this business – how to grow it, space it, harvest it, ship it.”

Icebox alternative
If you can’t find (or afford) seed for the varieties that are technically mini watermelons, you can still produce small, supersweet watermelons that customers will love. Many seedless watermelons that are technically in the class called “icebox watermelons” produce fruits almost as small – and just as sweet – as the mini varieties. In fact, the classifications don’t seem to have gotten settled yet. Some researchers refer to icebox watermelons as anything under 12 pounds, while others draw the line between mini and icebox at 6 pounds. Icebox watermelons have been around for a long time, and varieties include Dark Belle, Garden Baby, Fun Belle, New Queen, Orchid Sweet, Petite Perfection, Red Delicious, Sandiacita, Smile, Sugar Baby, and Yellow Doll.

Washington State University researchers Dr. Carol Miles, Madhu Sonde, Martin Nicholson, and Sean-Paul Cunningham evaluated nine varieties of icebox watermelons last year. Plants were started in the greenhouse and transplanted 3 feet apart through black plastic mulch.
“Harvest began Aug. 5, sixty-four days after transplanting, and continued until October 13,” the researchers reported. “Orchid Sweet and Sugar Baby were the largest in the study (7.96 and 6.61 pounds average) while Fun Belle and Yellow Doll were the smallest (3.27 and 3.91 pounds). Dark Belle and Smile produced the greatest number of watermelons (21 and 18 per five plants) and were high yielding, while New Queen produced the fewest (10 per five plants) and was low yielding.”

The researchers also noted that Red Delicious and Dark Belle were oblong while all others were round. Varieties also differed in skin and flesh color. “It was difficult to consistently determine when some varieties in this study reached maturity,” the researchers advised. “Growers will need to test fruit periodically throughout the harvest season to make sure fruit are fully mature and have good eating quality.”

The Washington team also test marketed their watermelons through Joe’s Place, a farm store in Vancouver. Customers paid full price for their watermelons, and those who returned a completed questionnaire received a $2 coupon toward their next purchase at the market. The watermelons were priced at 59 cents a pound, or an average of $1.80 – about half the price of a full-size watermelon. Customers were asked to rate on a scale of 1 to 5, with 5 being excellent, the eating qualities of the watermelons. On average, all were rated as very good but some were higher than others. Red Delicious, Dark Belle, Smile, and Fun Belle were rated highest while Sugar Baby and Orchid Sweet were rated lowest. All customers who purchased Red Delicious and 86% of those who purchased Fun Belle said they would purchase those varieties again, whereas 75% said they would not purchase Orchid Sweet or Sugar Baby again.

This year, Dr. Miles is trialing a large selection of small watermelons, including some that are classified as mini watermelons.

More on minis
Several of the Washington watermelons that are considered “icebox melons” averaged weights in the “mini watermelon” class. But when the minis were grown in Kentucky, many got as big as icebox watermelons, with average weights ranging from 8.1 to 12.5 pounds. The varieties with the highest number of marketable fruits were Extazy, Liliput, Valdoria and Sunday Special. Days to harvest ranged from 60 days for two seeded varieties, Manilla and Situla, to 90 days for the seedless varieties. Flavor was not evaluated in the Kentucky trials.

Researchers Richard Molinar and Shannon Mueller of University of California Cooperative Extension in Fresno also evaluated 10 varieties of small watermelons last summer. Watermelons were harvested beginning 78 days after transplanting. Individual weights varied considerably, and average weights ranged from 6.3 pounds for Petite Perfection to 12.8 pounds for Mini triploid 2618.
Researchers also measured Brix, or soluble solids, which reflects sweetness of the melons. Most were around 11 Brix.

“Petite Perfection, RWT 8149 and 5116 were a good size for the mini watermelon classification and had a good number of fruits per plot and a high soluble solids (Brix) rating,” the researchers reported. “They all had some of the thinnest rinds – which may be either good or bad depending on how they are handled. We did observe more internal bruising near the rind with the thinner rind varieties. Eight people evaluated colors and taste, and most preferred a darker red flesh rather than the orange-red color of the Petite Perfection, 5104, RWT 8149, Liliput and 2618.”

Classification confusion
It seems apparent that the distinction between mini watermelons and icebox watermelons is a small one, depending on climate and growing systems. As seed for the true mini watermelons – say, those as big as a grapefruit – becomes more available, growers will be able to experiment with planting dates, plant spacing, and fertility, to figure out the best way to produce these personal-sized melons.

For more information on the research cited in this article, agsyst.wsu.edu/Watermelon.htm
ucce.ucdavis.edu/files/filelibrary/742/13353.pdf