How to Grow Watermelons

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Brilliantly colored and dripping with sweet juice, a perfectly ripe watermelon is a refreshing sumer treat.
A flower forms on a watermelon vine.
A sling supports the heavy melons as they ripen.
Brilliantly colored and dripping with sweet juice, a perfectly ripe watermelon is a refreshing sumer treat.Click To Enlarge

Brilliantly colored and dripping with sweet juice, a perfectly ripe watermelon is a refreshing sumer treat.

Photo: André Baranowski

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On a hot summer afternoon, we didn’t need much more than the shade of a mimosa tree and a watermelon to stay cool. My grandfather would split one open, spear the flesh with his fingers, and pull out a chunk. We ate it with our hands and weren’t afraid to make a mess. Watermelon and I were a love match made in heaven—literally it turns out. Little did I know then that I would grow up to marry a water­melon farmer whose family has grown the fruits for the past 90 years.

Juicy, ripe watermelon
  Juicy, ripe watermelon is a summer treat.

Though it would be easy enough to bring home watermelons from the field, we enjoy growing them in the garden beside the house. Breeding has reduced watermelons’ demand for luxury berths in the garden. As you will see, they can even be trellised. When you pick and eat a perfectly ripe watermelon from your own garden, you will understand the meaning of home-grown fun.

Finding time and space
No getting around it, the 25-lb. behemoths such as ‘Crimson Sweet’, a round, red-fleshed melon with dark green stripes, and ‘Royal Majesty’, also red-fleshed but oblong, require 6 ft. by 4 ft. garden plots for each plant.

On the other hand, icebox watermelons such as ‘Sugar Baby’, a round, red-fleshed fruit with a very dark green skin, and ‘Yellow Doll’, with its namesake flesh and light green skin, are perfectly suited for small gardens. They’ll do fine with 2 ft. by 4 ft. spaces per plant and turn out fruits of 5 lb. to 18 lb.

You can tighten the quarters a bit more with a bush type watermelon, such as ‘Garden Baby’. These compact vines require just a 2 ft. by 2 ft. spot and can even be grown in a large container on a patio.

Although a warm-climate crop, watermelons can be grown in northern areas if you have the right variety. Icebox types like ‘Sugar Baby’, ‘Yellow Doll’, ‘Tiger Baby’, and ‘Garden Baby’ mature in 75 to 85 days, which should be enough time for a bountiful harvest. The larger watermelons typically take 85 to 95 days to mature. On the Delmarva peninsula, we begin picking watermelons around July 4 and continue through early to mid-September, harvesting two or three fruits per plant. But it won’t pay to rush watermelon seed into the ground when it’s cool. The plants will just idle until warm weather arrives.

The origins of the watermelon
Whence watermelons came remains a botanical conundrum. Southern Italy, the source of so much good eating, enjoyed for a time the status of chief suspect as the original home. The case could not be closed because the region harbored no wild watermelon plants.

In 1850, explorer David Livingstone called attention to Africa by reporting a great oasis of wild watermelons in the Kalahari Desert. Claims from other regions can be found as well, though most sources point to Africa first. Origins aside, these wet and weighty fruits have been borne across the continents and seas, with good reason. Mark Twain proffered a fine line for the fruit’s star-spangled popu­larity. “When one has tasted it, he knows what the angels eat.”

Get fruit faster with transplants

Transplants are great because the plants will bear watermelons about a week sooner than their direct-seeded counterparts. Start seeds four weeks before you plan to plant in the garden. Many types of containers work, as long as they have good drainage. Those that are 2 in. across are ideal and produce well-rooted seedlings that will take off after transplanting.

  Tips for growing watermelon
• Watermelons grow best in well-drained soil with a pH of 6.0 to 6.8.
• Form planting mounds about 3 in. tall and 12 in. to 18 in. wide to improve drainage.
• To direct seed, plant two seeds 1 in. deep in each mound and thin to one plant after they have at least two leaves.
• Improve growth by controlling weeds with cultivation, which also helps aerate roots.

Watermelon seed germinates well at temperatures of 70˚ to 95˚F and takes four to six days to emerge. Harden off transplants by reducing the frequency of watering to slow growth, and move the plants to an area with cooler temperatures for about a week. Transplants ready for the garden will be 4 in. to 5 in. tall, with two or three true leaves. Set them out in well-drained soil. Watermelon plants don’t like “wet feet” and are great candidates for raised beds.

Seedless fruits take special effort. Seedless watermelons, which, despite the name, do contain soft, white seeds, don’t produce their own pollen. They require the company of a pollenizer, which can be any seeded variety. Every third plant in a row of seedless watermelons should be a seeded variety. Choose a pollenizer with different surface markings so it’s easier to tell at picking time which have seeds and which do not.

With seedless varieties, I especially prefer transplants. The seeds are expensive, 15 cents to 17 cents each, and they are fussy about germinating. The seed coat tends to adhere to the cotyledons and needs to be removed so growth isn’t hindered. Whatever extra work is involved, though, is worth it to me because I love the taste of these melons and I don’t have to pick out the seeds for my children.

Proper nutrition depends on watering

  Sources for watermelon seed
Harris Seeds
355 Paul Road
P.O. Box 24966
Rochester, NY 14624-0966

Otis S. Twilley Seed Company
121 Gary Road
Hodges, SC 29653

Willhite Seed Inc.
PO Box 23
Poolville, TX 76487

Watermelons need steady watering throughout the season, at least 1 in. per week. Blossom-end rot, caused by a calcium deficiency during fruit development, can be a problem. Maintaining the proper soil moisture makes calcium available when it’s needed.

Watermelons are heavy feeders and may need a boost for good growth if you don’t have rich soil. Laying down 3 lb. of 10-10-10 fertilizer or the organic equivalent per 100 sq. ft. just prior to planting would not be out of line. A little side dressing when the vines begin to run and a little more after the first fruit is harvested may be in order as well.

Even heavyweights face attacks. The best defense against watermelon woes, such as gummy stem blight, is planting disease-resistant varieties, rotating crops, and spacing plants to permit good air circulation.

Don’t mistake a yellow patch on the top of the melon for disease. It’s sunburn, and if you see it, just cover the fruit with a basket or cloth.

As for insects, keep an eye out for cucumber beetles. They do the most damage early in the season when plants are young and susceptible.

Pull watermelons out of thin air

If you’re wondering what you’d have to push out of your garden to make room for watermelons, don’t despair. All you need to do is train your watermelons to climb. As the vines, which should be about two feet apart, begin to run, send them up a sturdy trellis. You will need to tie the runners to the trellis, since watermelons are not natural climbers.

Watermelon vine on a trellis Fruit in a sling
Cllimbing is learned behavior. Watermelons don't climb by habit, but once shown the way they can rise with the best.   Watermelons rest easy in hammocks. Swelling fruits will definitely need support on the trellis, and an old T-shirt makes a perfect sling.

Once the plants set fruit, support the burgeoning melons with slings, which can be made with cheesecloth, nylon stockings, or old T-shirts. If the sling completely covers the fruit, it provides protection from insects. In addition to saving space, trellising improves air circulation and helps prevent disease.

Of course, trellising requires more work than just letting the vines run over the ground. And the flowers of trellised plants are more prone to drop in a stiff wind before the fruit sets. But if you’re up for a challenge, or stymied over how to upstage the neighbors’ tomatoes, harvesting a trellised watermelon may be just the trick.

How to tell when they’re ready

Although determining the optimum maturity of a watermelon can be difficult, the plant provides clues. First, inspect the curly tendril near where the watermelon attaches at the stem. It should be dead or brown.


Learn more:

Video: How to Pick a Ripe Watermelon

From this angle it definitely looks like a fruit.   Photo by Muffet under the Creative Commons Attribution License 2.0.

How to Grow Sweet Watermelons

Make Room for 'Moon and Stars'...

Watermelon Carving Ideas


Second, turn the melon on its side and inspect the belly. The underside of the watermelon should be creamy-white for seeded varieties and golden yellow for seedless varieties.

Third, thump. A ripe melon should deliver a deep, low-pitched sound. This has always been a popular way to detect ripeness, but I have found it takes a lot of experience to truly tell the right sound.

And finally, if you’ll notice, watermelons have a shiny, bright green color on the outside as they grow. When the watermelon matures, this coloring will dull. This method of determining ripeness also takes practice, and it amazes me to watch my father-in-law harvest watermelons. He can stand at a distance and tell you if the watermelon is ripe or not. He teases me because, although I have had quite a bit of experience harvesting, I still check for the brown tendril and the color of the belly to be sure it’s ready.

Watermelon recipes

Now that you've grown them, try them in soup, smoothies, relish and salad.

Strawberry Watermelon Soup   Watermelon Smoothie with Cardamom
Strawberry Watermelon Soup 
(recipe by Ken Haedrich)
  Watermelon Smoothie with Cardamom 
(recipe by Didi Emmons)
Curried Watermelon-Rind Relish   Watermelon Salad with Habañero and Basil
Curried Watermelon-Rind Relish
(recipe by Didi Emmons)
  Watermelon Salad with Habañero and Basil
(recipe by Didi Emmons)

by Tracy Wootten
August 1998
from issue #16

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posted in: watermelon

Comments (24)

timonrooster writes: i love it.
Posted: 3:40 am on August 20th
charisbaker writes: Good one...
Posted: 2:01 am on August 20th
ballidhoot52 writes: I love this guide
Posted: 12:29 am on July 27th
lyunmoss writes: watermelon is my favourite.
Posted: 5:53 am on July 26th
DonnaCox writes: want to eat this.
Posted: 2:13 am on July 26th
Dallinlarsen555 writes: good one
Posted: 12:51 pm on October 6th
matthewtweedie writes: very nice
Posted: 12:09 am on September 30th
TonjeFjell writes: I love this guide! Watermelon is one of my favorites!
Posted: 1:34 pm on July 31st
TracyPoren writes: I love to eat fresh watermelon and very good post for how to growing watermelon
Posted: 2:52 am on February 11th
SaireyGamp62 writes: I grow 3 watermelons, Crimson Sweet, Ali Baba (seeds are hard to find but once I found a few have saved them, and the last one is Black Diamond. I usually plant in rich compost with mineral worked into each planting spot. Water the ground well before transplant, then mulch heavily with wood chips, and cut the water off them them last week of July. They ripen at different times so we have melon from August thru Mid- Oct although if frost threatens i harvest and refrigerate

The Ali Baba's are stunning,
Posted: 11:41 pm on December 27th
ZoeyJ writes: I just love watermelons. Last year I`ve tried to grow, but nothing happened. I see my mistake in this article, so this year I'll succeed. Thank you so much for sharing!
Posted: 3:47 am on June 16th
growwatermelon writes: Thanks for this awesome guide
Posted: 10:07 am on November 24th
RiverDivider writes: Are watermelon one time plants or do the stems grow more melons after you harvest them? I'm an extreme beginner :).
Posted: 4:59 pm on May 12th
coolveggie writes: hffv
Posted: 6:35 pm on February 16th
coolveggie writes: when do you plant melons in NJ?
Posted: 6:34 pm on February 16th
coolveggie writes: cool! i will grow some. when do you plant watermelons in jersey. not the cow jersey the state jersey.
Posted: 6:33 pm on February 16th
captscot writes: Hi, last summer I grew two types of watermelon. One a Watson, the other Sugar Baby. Both grew OK and produced about five melons each. The Watson made a typical good ripe melon. The Sugar Baby produced melons from about 8" to 11" in diameter. I waited until late fall, until the plants dried up, to pick them. However, each melon when I cut into them was white inside, not sweet, and obviously not ripe. It is now February and I still have one Sugar Baby left, stored in the house and hoping that this last one might now be ripe, what happened?
Posted: 6:06 pm on February 15th
arconagbuya writes: I am a beginner in planting watermeronls, and as usual, I worry a lot if the baby watermerons will make it through. The soil in our place is dry, and I keep on watering them. The babies are 2-3 inches now and just have 1 true leaf sprouted but I already put them in the ground.

This article informs me a lot. Thank you very much!
Posted: 3:32 am on February 6th
pinkdancer308 writes: sounds simple enough! thantks 4 the advice. i will start growing them soon. i live in the tropics so its hot all through the year :)
Posted: 5:12 pm on September 13th
PrairieGardener writes: I have a question. The vines are getting very long. Should one ever cut them at the end to encourage fruit production, rather than more vines and blossoms?
Posted: 10:36 pm on August 10th
4bboys writes: @kubota2410, sounds like it might be a calcium deficient problem. You should use a high nitrogen fertilizer in early stages, but cut back on nitrogen & give lots of potassium once they flower & fruit.
Hopes this helps :)
Posted: 1:09 pm on July 6th
kubota2410 writes: hello, i planted some watermelons and they have ran out about 4 feet and was looking so good, i had about 12 melons and then they started to rot on the ends. is there any thing i can do to turn them around to grow some good ones,or is it to late? thanks
Posted: 5:07 pm on June 28th
petuniababi writes: This article was so educational!!Last year i was so lucky in growing seven nice sized melons,but picked them too soon.Now i know what to do and maybe this year we can enjoy them.Thanks!!
Posted: 1:48 pm on June 8th
psg writes: A very good article for a beginning watermelon grower like me. And the timing is perfect. I have 4 sugar baby watermelons nearing what tI think might be harvesting size. but I don't want to pick too early. The clues in the artilce give me a much better criteria for picking than just the sound when you thump it. Thanks
Posted: 11:06 am on July 23rd
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