Growing Watermelon

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Watermelons are fun and easy to grow, as long as you know a few secrets about things like when and how much to water, and when to harvest.
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Two young farm girls eat homegrown watermelon next to the garden.
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Two melons thrive in a market-garden watermelon field.
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Bradford varieties, shown at right, are extremely rare to find, so if you’re lucky enough to find seeds, it’s wise to save your own seed from the legendary fruits.
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Cream of Saskatchewan is an 80-day watermelon that’s well-suited to northern growing. Fruits are around 8 to 10 pounds with sweet, tasty, cream-colored flesh.
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Moon and Stars melons come in a variety of flesh colors.
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Chris Cross is an almost-extinct variety first bred in Montrose, Iowa. Fruits are 15 to 20 pounds and have a tasty, crisp, red flesh.
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Black Seeded Ice Cream is an old sweet-flavored, pink-fleshed variety that was popular in the 19th century.
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Golden Midget matures in just 70 days, and weighs around 3 pounds.
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Watermelon for sale at a market stall on the street.

Summer just wouldn’t be the same without picnics and cooking outdoors. And what’s a picnic without watermelon?! Maybe you get that melon from the supermarket, or if you’re lucky, a roadside stand. Maybe it’s local, but more likely, it comes in from one of the Southern states or California on a semitrailer piled high with melons. It never fails: That “good one” is always at the bottom of the bin.

Now, imagine serving up your own homegrown melon at the next Labor Day picnic, knowing for certain it’s a good one. That’s not a pipe dream: You can grow good watermelons right where you live.

The right melon

With more than 1,200 varieties, there’s a melon that’s right for just about any growing condition in the United States, even as far north as Alaska. Spend some time going through seed catalogs, and you’ll be amazed by what you discover. Melons come in all sizes, from 1-pound single-serve to 100-plus-pound record-breakers. Rinds can be hard and thin, good for shipment and storage; or tender and thick, perfect for making watermelon pickles (see recipe linked below). Even their flesh comes in a variety of colors: crimson, orange, yellow, even icy white.

The most important information in the catalogs usually gets overlooked — days to maturity. Watermelons can mature in as few as 70 days and as many as 110 days. These are counted from the day you plant your melons in the garden, whether as seeds or transplants. They absolutely must be warm days for best flavor, at least 65 degrees Fahrenheit, day and night.

Stalwart varieties

Charleston Gray produces large, 20- to 40-pound oblong fruits in 90 days. The flesh is deep red, and the rinds are thick enough for watermelon pickles.

Cream of Saskatchewan gets by with a shorter season, needing only 80 days to deliver sweet, pale yellow, even cream-fleshed melons. The melons are 8 to 10 pounds, round, icebox type fruits, perfect for the fridge.

Moon and Stars is more a family of heirloom melon varieties, and it’s a popular one. They need a season ranging from 90 to 100 days. All types are large melons, ranging in size from 15 to 40 pounds. The fruits are oblong, with dark green rinds dusted with tiny yellow “stars” and larger “moons.” There are red-,
pink-, orange-, and yellow-fleshed strains available. Moon and Stars also makes excellent pickles.

For seedless melons, try Harvest Moon. A descendant of Moon and Stars, Harvest Moon yields 18- to 20-pound pink-fleshed seedless fruits in 90 days. Note that seedless watermelons require cross-pollination. Pollinator seeds are included in each packet, so plant every seed.

Hailed as one of the most flavorful melons, Bradford Family also holds the reputation of the deadliest. In the past, growers would go to great lengths to protect their Bradfords from marauders, including armed guards, electrified melons, and even poison-laced bait melons. Bradford delivers large, 40-pound melons in a surprising 85 days. Its red flesh is ideal for fresh eating, distilling brandy, and making molasses; and the rinds are reputed to make the best pickles. Almost lost since the middle of the last century, the variety has been preserved by the Bradford family. Seeds are available on a limited basis, so if you get a hold of some, it’s wise to save your own seed.

Preparing soil

Watermelons need deep, sandy soil, preferably amended with plenty of organic matter. Till your soil as deeply as possible, working in plenty of compost or composted manures.

Watermelon roots can reach 6 or more feet deep, if the soil allows it. If you have heavy, compacted clay, all is not lost. Burpee Seeds recommends building a mound on top of the ground, mixing two 40-pound bags of compost or composted cow manure with one bag of potting mix. You can easily do this wherever you want to plant watermelons. At the end of the season, simply pull the vines and rake the soil flat, then pick a new spot the following year.

Heat the soil

Make use of microclimates, small pockets of warmer conditions. Place your melon patch in front of a heat sink, such as a south-facing brick wall. Protect your spot from the wind early in the season with a temporary burlap windbreak.

Begin warming your soil early in spring. Cover the soil with clear plastic or use water-filled plastic hot caps to take advantage of the sun’s energy. Cold frames or high tunnels are even more effective at turbo-charging your season.

Well-timed planting

Wait to plant until the soil temperature reaches 65 degrees, 4 inches below the surface. In my area, that’s usually when peonies begin to bloom. The choice is up to you whether to direct sow seeds or transplant started plants; there are benefits to each method: Seeds don’t suffer transplant shock, while plants started indoors have a better germination rate.

If you choose transplants, it’s best to start them in large biodegradable pots to avoid disturbing the roots at planting time. When you plant them, plant the whole thing, and peel back the rim of the pot. Exposed pot material can wick moisture away from roots, drying them out and possibly killing the vine.

Plan on two vines per hill. Plant four to six seeds per hill if you direct seed. Once they are up and growing, nip out all but the two strongest seedlings. Allow at least 4 feet between each hill, and 10 feet between rows.

Eliminate competition

Weeds can become a threat, draining moisture and nutrients away from your vines. Keep them in check by covering the ground with organic mulch. Straw, shredded leaves, or grass clippings (as long as they’ve been dried) make excellent mulches. They also protect your melons from ground contact and rot.

Early in the season, when the vines are still small, you can make use of the space between hills by planting lettuce or other fast-growing spring crops between the hills. Once the vines begin rambling, it’s time to harvest the remainder of those spring crops to give your vines elbow room.

Water with care

Developing watermelon vines appreciate a steady supply of water. Provide an inch of water per week, less when it rains. Since mildew and other diseases love wet leaves, especially overnight, avoid wetting the leaves or watering late in the evening. Consider using soaker hoses laid out at the base of each hill. Alternately, set leaky gallon jugs of water at each hill to provide a slow, soaking drink. The water should soak to at least 6 inches deep every time you water.

Some growers recommend feeding the developing vines with a diluted solution of Borax for sweeter melons. Mix 1 tablespoon of Borax with each gallon of water for an occasional boron boost. At the same time, feed your vines every week with a solution of 1 tablespoon of liquid fish fertilizer per gallon of water.

Once the vines set fruit and the melons begin maturing, cut back on the water severely, watering only in the event of a drought. At this point, water will only dilute the sugars and flavors in your melons. Speaking of setting fruit, allow only two melons per vine for the best harvest possible.

Use your melon

Picking a ripe melon can be a challenge if you don’t know what to look for. Melons don’t just slip off the vine, but they do let you know when they’re ripe. As a melon ripens, its belly will fade from green through white, then yellow or cream. Some gardeners also claim that a ripe melon will also form faint “ribs.” I’ve never been able to reliably pick a good one according to ribbing. The big giveaway lies in the tendril, that little corkscrew growing by the melon. When it dies and dries up, you’re in business. Don’t pick a melon too early — once it’s off the vine, it’s finished.

There’s a myth about watermelons that needs busted: Watermelons will not cross with cucumbers. Yes, they are closely related. And yes, watermelons will readily cross — with other melons. However, contrary to popular belief, they won’t cross with cucumbers. Even if they did, it wouldn’t affect the resulting fruit; only the seeds would be “cucamelons.” Don’t blame a bland melon on an innocent pickle patch. It may have been picked too early, the vines might have had a late start or wilted, the season may have been too cool or too rainy, but cucumbers had nothing to do with it.

Finally, your moment of truth has arrived. You’ve pored over seed catalogs, choosing the perfect melon. You picked the best spot in the garden, sunny and protected. You warmed the soil early and fed it well. You planted at just the right time. You kept the weeds out. You watered early but not too long. You waited patiently for your melons to ripen. Finally, you picked each melon at just the right time.

Now it’s time for a little flair, a little picnic ceremony. Go ahead, grab that carving knife (or sword if you prefer) and do the honors. Your melon will be a good one. Have a slice of summer. There’s nothing like it.

Find out what to do with all those watermelon rinds: Watermelon Pickles Recipe.

Check out even more heirloom cultivars of delicious watermelons that thrive in the North American countryside.

Andrew Weidman lives and writes in Lebanon, Pennsylvania. In his opinion, nothing improves a summer evening like a big wedge of watermelon, with or without seeds.

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