By Patty G. Leander
Contributing Editor
Nothing heralds the arrival of summer quite like a cold, crisp slice of watermelon, dripping with juicy sweetness. Watermelons, like tomatoes, are best enjoyed in season and fully ripe, and fortunately Texas has no shortage of top-notch growers and watermelon festivals. Indeed, watermelon is a reason to party. As a child, my older sister preferred watermelon over cake for her July birthday, a tradition that has held for more than half a century. From Luling’s renowned four-day Watermelon Thump in late June to Hempstead’s “Watermelon Capital of Texas” Annual Watermelon Festival in mid-July, this quintessential summertime fruit and principal Lone Star crop is celebrated with parades, queen coronations, seed-spitting contests and melon judging, with Grand Champion melons consistently weighing in at well over 100 pounds.
Watermelon (Citrullus lanatus) is generally consumed as a fruit, but botanically it is a member of the Cucurbitaceae family. The wild form of watermelon, bitter in flavor with pale flesh, is indigenous to the desert regions of Africa, where it served as a sort of canteen of liquid refreshment for anyone trekking through the desert or journeying through the afterlife. From icebox-sized ‘Sugar Baby’ to classic heavyweights like ‘Black Diamond’ and ‘Jubilee’, watermelons come in a range of colors, sizes and shapes.
A LESSON IN POLLINATION
The important role of pollinators cannot be overlooked when it comes to successful watermelon production. Watermelon blooms are dependent on insects, mainly honeybees, for pollination, an intricate process we often take for granted. It’s not as simple as one bee collecting pollen from a male flower and delivering it to a female bloom and presto — a baby watermelon develops. Time of day (flowers are most receptive in the morning), size of the ovary, overcast conditions and foraging behavior of the bees, even their body size, can all affect the success rate of pollination. Watermelon growers often have beehives in their fields to ensure adequate activity and successful pollination. You don’t have to become a beekeeper to grow watermelons, but you do want to encourage pollinators and avoid the use of toxic pesticides. According to Dr. Larry Stein, Associate Department Head/Professor and Extension Horticulturist, Texas A&M AgriLife Extension Service, a single flower must be visited by a bee approximately 15 times to complete a successful course of pollination. It takes a lot of pollen to fertilize all those watermelon seeds, and a melon that is not successfully pollinated will be misshapen and off-flavor. The more I learn about the botany, pollination and development of watermelons, the more I realize how lucky I’ve been to have a fruitful watermelon harvest in my backyard garden!
Like cucumbers and squash, male and female flowers develop on the same plant, so complementary plants are not needed unless you are growing seedless watermelons (see sidebar). However, multiple plantings — if you have the space — will yield a larger harvest because a single watermelon plant may only produce two or maybe three melons. Under ideal conditions, plants start to bloom about 8–10 weeks after seeds germinate. Once a flower is pollinated, it will take an additional 30–40 days for the fruit to develop and reach maturity.
CULTIVATION
Melons grow best in sandy loam but are tolerant of heavier soils as long as the soil is well drained. Generous spacing, especially for large-fruited melons with vigorous vines, is important for root development below ground and air circulation above ground, which will help prevent disease. To get peak production, experts recommend spacing plants 4-to-6 feet apart in the row, with 6 feet between rows. An alternate growing arrangement is two plants in an 8 ´ 8-foot plot. Though it may be tempting to pack plants in more tightly, crowding will result in increased competition for nutrients and water, disease pressure, poor pollination and ultimately inferior fruit. Fortunately, there are a number of compact varieties better-suited for small gardens, such as ‘Cal Sweet Bush’ and ‘Mini-Love’, that can be grown in a 4 ‘ 4-foot square. To save space, these smaller varieties can even be grown vertically, on a sturdy fence or trellis. As melons develop, cradle each one in a sling made of an old T-shirt or pantyhose for support.
Watermelons need a long season of warm weather, from planting to harvesting, and Texas delivers. Seeds require soil temperature above 70° for healthy germination; trying to rush the season by planting in cold soils will result in rotting seeds or stunted, slow-growing plants. Seeds are generally direct-seeded in slightly raised mounds of soil (hills). Prepare the hills a few weeks before your anticipated planting date by amending with a layer of compost and about one cup of commercial garden fertilizer per hill. Water the hills a day or two before planting so that the soil is moist. At planting time, plant three or four seeds in each hill, a few inches apart and about 1 inch deep. Seeds will germinate in about a week, and two weeks later should be thinned to the two strongest seedlings per hill. This step of thinning is painful for many gardeners, but it is important to give watermelon plants space to grow above and below ground, without overcrowding or competition.
When plants begin to vine, side-dress with 2–3 tablespoons of high-nitrogen fertilizer sprinkled around the perimeter of each plant. Gently work the fertilizer into the soil and water well. Mulch plants before they begin to sprawl and provide moderate and consistent moisture, ideally with drip irrigation or soaker hoses to avoid wetting the leaves. Excess moisture near harvest time can result in poor flavor, so cut back on watering two or three weeks before your anticipated harvest. Monitor for pests, such as cucumber beetle, and treat, if needed, to prevent an infestation. Powdery mildew can be a common problem during rainy periods, but a preventive approach — full sun, adequate air circulation, drip irrigation — will help prevent the disease.
Bacterial fruit blotch is a serious disease that affects watermelon, especially in large commercial plantings. Outbreaks have occurred sporadically in watermelon-production areas, causing large losses due to blotchy lesions that form on the rind of mature fruit. This damage is mostly cosmetic; the interior fruit poses no safety risk, but the losses for growers are devastating because they cannot sell disfigured melons. Home gardeners should follow preventive measures already mentioned to minimize disease risk. If an infection is confirmed, a copper-based bactericide/fungicide can be used to prevent its spread. For more information on this disease refer to the following AgriLife publication by plant pathologist and Extension Specialist Dr. Thomas Isakeit: https://agrilifeextension.tamu.edu/library/gardening/bacterial-fruit-blotch-of-watermelon/.
GROWING TRANSPLANTS
Most varieties will take 80–100 days to reach maturity, but there are two approaches to planting watermelons that will help lead to an earlier harvest. One is to utilize black plastic to warm the soil and deter weeds; the other is to utilize transplants. Transplants allow farmers and gardeners to easily monitor the early growth of seedlings to ensure germination success. It also eliminates the need for thinning because seedlings can be planted and spaced precisely down a row or in a garden bed.
According to Dr. Stein, an ideal watermelon transplant will have only two sets of leaves, the cotyledons and the first set of true leaves. The best way to achieve this ideal transplant is to grow it yourself, an easy and rewarding process that only takes about four weeks. Because watermelons don’t like their roots disturbed, it is best to use biodegradable peat pots or cowpots (plantable pots made from composted cow manure). Fill 3- or 4-inch containers with sterile potting mix and wet thoroughly. Allow to drain and then plant seed (2 per pot) about 1/2” deep and cover with a thin layer of inexpensive cat litter. Place pots in a tray or flat and cover with clear plastic. The plastic will help maintain high humidity, while the clay particles will create the moist environment needed for germination.
Place the flat of seeds on a heat mat or in a warm area (80–85°) for two or three days and then move the seeds to a cooler environment (70–75°). Seedlings should emerge within 5–7 days and then plastic should be removed. Allow the potting mix to dry slightly between watering. Once seedlings have their first set of true leaves, it is time to plant them outside. Harden them off for a couple of days by gradually exposing them to outdoor conditions and full sun. Don’t be tempted to plant earlier or grow bigger transplants — they will likely be stunted, will struggle to get established and will take longer to reach maturity. Set transplants into moist, prepared soil and water with a transplant solution or half-strength liquid fertilizer.
RECOMMENDED VARIETIES
Did you know that Texas is home to a 100-year-old seed company that specializes in first-class watermelons? Willhite Seed of Poolville, Texas, began as Willhite Melon Seed Farms, a small, family business run from the home of founder and watermelon grower T. A. Willhite. Willhite had gained a local reputation for growing superb watermelons, and in 1904 he received world-wide recognition when his watermelons were awarded first prize at the World’s Fair in St. Louis. Over the years, Willhite Seed has expanded their offerings, providing quality vegetable seed to Texas and beyond, as they continue improving cultivars for both commercial and home-garden use. They offer an excellent selection of dependable watermelon varieties, including the treasured heirlooms ‘Black Diamond’ and ‘Moon and Stars’; icebox types such as ‘Sugar Baby’ and ‘Crispy Critter’; as well as popular open-pollinated varieties that include ‘Crimson Sweet’, ‘Dixielee’ and ‘Legacy’.
The size of your garden may determine the type of watermelon you choose to plant. If compact varieties are better suited for your growing space, consider All-America Selections Winners ‘Sweet Beauty’ (AAS 2004), ‘Mini Love’ (AAS 2017) and ‘Cal Sweet Bush’ (AAS 2019). These small-fruited varieties produce “personal-size” melons weighing 5–10 pounds and reaching maturity in 75–85 days from planting seed.
HARVEST
Picking a ripe watermelon is easier to do in one’s own garden than at a grocery store because when you grow your own there are several clues to watch for. First, the seed packet will tell you the approximate days to harvest for the particular variety you are growing. Note the days to harvest and record the date seed was planted. For example, if you plant seeds of ‘Jubilee’, a 90-day variety, on April 15, it will be nearing harvest around July 15. At that time start watching for other clues to ripeness. Turn the watermelon over and look at the ground spot; it should be a creamy buff or yellowish color. Look at the tendril nearest the stem where the melon attaches to the vine. As the melon reaches maturity this tendril will start to wither and turn brown. Also note the rind during the growing season; it will turn from glossy to dull and if the melon is a variety with stripes, the stripes will become more pronounced. When it comes to thumping, an immature melon produces a sharp ping, while a mature melon makes more of a dull, hollow sound.
When it comes to eating watermelon, to each his own. Many creative ideas for preparing melon can be found in cookbooks, at trendy restaurants and on food websites, from watermelon cocktails to savory salads to “ham” slices that are grilled, smoked or roasted. I don’t mind making chips out of kale or taco meat out of cauliflower but waiting three months to harvest a ripe watermelon from my garden and then grilling this summertime treat to eat hot seems like an abomination. Chilled and unadulterated — that’s the way to go, at least for those first few slices. If I find myself lugging a monster melon to the kitchen, with plenty of melon meat to spare, I do enjoy the classic combination of watermelon and feta as well as the refreshing flavor of diced melon in a salsa peppered with cilantro and jalapeños. Excess watermelon can also be cubed and frozen to use in blended beverages or as ice cubes. No matter how you choose to enjoy it, watermelon is yet another botanical wonder that keeps me in awe of the diversity of the food we have available to us, especially the fruits and vegetables we can grow ourselves. tg
Watermelon (Citrullus lanatus) is generally consumed as a fruit, but botanically it is a member of the Cucurbitaceae family. The wild form of watermelon, bitter in flavor with pale flesh, is indigenous to the desert regions of Africa, where it served as a sort of canteen of liquid refreshment for anyone trekking through the desert or journeying through the afterlife. From icebox-sized ‘Sugar Baby’ to classic heavyweights like ‘Black Diamond’ and ‘Jubilee’, watermelons come in a range of colors, sizes and shapes.