Citrullus lanatus (Watermelon)

Watermelon: Juicy, Refreshing, and Full of Benefits

Citrullus lanatus, commonly known as watermelon, is a beloved summer fruit that delights with its crisp, sweet flesh and hydrating qualities. From backyard picnics to gourmet salads, watermelon is more than a seasonal treat—it’s a rich source of vitamins, antioxidants, and hydration. With its deep roots in African history and global popularity today, watermelon comes in a variety of types including red, yellow, orange, and even seedless.

What is a Watermelon?

Description

Watermelon is a sprawling, vining annual plant in the Cucurbitaceae family, related to cantaloupe, zucchini, and cucumber. It produces large fruits called pepos, with hard, often striped rinds and juicy, sweet flesh that can be red, pink, yellow, orange, or white. Most watermelons are oval or round and weigh anywhere from 1 kg to over 90 kg.

Native Range

Watermelon was domesticated in Northeast Africa, with its closest wild relative being the Kordofan melon of Sudan. Evidence of watermelon cultivation in Egypt dates back to 2000 BCE, and the fruit later spread through the Mediterranean and beyond.

Growth Habit

Watermelon is a prostrate or climbing annual vine. It grows vigorously during warm weather, sending out long, hairy stems that trail across the ground or climb with the aid of tendrils. The plant’s growth is rapid in full sun and well-drained, fertile soils, and it is typically cultivated as a summer crop.

Size

Watermelon vines love to stretch out—they can sprawl as far as 33 feet (10 meters), so give them plenty of room to roam. As for the fruit, sizes can vary a lot. Wild watermelons are usually about the size of a small melon, around 8 inches (20 cm) across. But the ones we grow in gardens and farms? They can be real giants—often over 24 inches (60 cm) wide and weighing anywhere from a few pounds (1–2 kg) to over 40 pounds (20 kg). Some record-breakers have even tipped the scales at more than 27 kg (60 pounds)!

Flowers

Watermelon plants are pretty cool when it comes to flowers—they’ve got both male and female blooms growing on the same vine (yep, they’re monoecious if you want to get technical). The flowers are bright yellow and about an inch wide, each popping up on its own little fuzzy stem where the leaf meets the vine. First, you’ll see the male flowers show up. Then come the female ones, which have a tiny baby watermelon (called an inferior ovary) at the base. Once those get pollinated, boom—fruit starts to grow!

Leaves

Watermelon leaves are big, bold, and kind of fuzzy—especially when the plant is young. They’re usually made up of three to five deep lobes and can grow up to 8 inches (20 cm) long and wide. Each leaf sits on a long stalk that connects it to the vine. When the plant’s just getting started, the leaves and shoots are covered in soft, yellowish-brown hairs that give them a woolly feel. As the watermelon matures, those hairs start to fade, and the leaves smooth out a bit.

Fruits

Watermelon fruit is basically summer in a shell. It’s a big, round (or sometimes oblong) berry with a tough green rind that can be solid, striped, or all speckled-looking depending on the type. Inside, you’ll usually find juicy red or pink flesh—but some varieties surprise you with yellow, orange, or even white! Most have lots of smooth, flat seeds, though seedless versions are super common these days. What really makes watermelon a fan favorite is its super high water content (over 90%!), crisp bite, and naturally sweet, refreshing flavor.

Hardiness

Watermelon is a warm-season crop that thrives in hot, sunny climates. It is frost-sensitive and best grown in regions with long, warm growing seasons. The plant requires soil temperatures above 21°C (70°F) for optimal germination and growth and does not tolerate cold or prolonged wet conditions.

Wildlife

Watermelon flowers attract pollinators, especially bees, which are essential for fruit set. The fruit is consumed by a variety of wildlife, including birds, mammals, and insects. In some regions, wild watermelons serve as an important water source for animals during dry periods

Toxicity

Watermelon fruit is non-toxic and widely consumed by humans and animals. The rind is also edible when cooked or pickled. However, wild relatives such as Citrullus amarus may have bitter, inedible fruits due to high levels of cucurbitacins, which can be mildly toxic if consumed in large quantities. Cultivated watermelons are safe for human consumption.

How Nutritious is Watermelon?

Watermelon isn’t just refreshing—it’s also full of nutrients and super hydrating. It’s low in calories and high in vitamin C, lycopene, and water—basically, summer in a slice.

Here’s what you get in one cup (152 g) of fresh watermelon:

Beyond the numbers, watermelon is rich in citrulline—an amino acid linked to heart and muscle health—and full of antioxidants like vitamin C, lycopene, and carotenoids. Thanks to its 90% water content, it’s one of the best fruits to help you stay hydrated on a hot day. And it does all that while being light and sweet—win-win!

Health Benefits of Watermelon

Regularly enjoying watermelon can lead to better diet quality and higher nutrient intake in both kids and adults. It’s one of those rare treats that tastes indulgent but is actually really good for you!

Whether you’re sipping it as watermelon juice, enjoying it in a watermelon feta salad, or blending it into a watermelon smoothie, this fruit is a powerful ally for health. And don’t forget the watermelon seeds—they’re packed with nutrients too!

How to Tell if a Watermelon is Ripe

Knowing how to pick a good watermelon can make the difference between a bland bite and a juicy delight. Here’s what to look for:

• Field Spot: Flip the melon to check the underside. A creamy yellow spot means the watermelon ripened in the sun—perfect! A white or pale green spot? It may have been picked too soon.
• Sound: Give it a tap. A ripe watermelon should sound deep and hollow. A dull thud may indicate overripe or underripe flesh.
• Weight: Pick up a few watermelons of similar size—choose the heaviest one. Water equals juiciness, and heavier melons are often sweeter.
• Skin Texture: The rind should be dull, not shiny. Shiny skin usually means it’s not ripe yet.
• Webbing: Brown, rough webbing on the skin is actually a good sign—it means bees pollinated the flowers frequently, which can lead to sweeter fruit.
• Shape: Choose a symmetrical watermelon without lumps or irregular bumps, which may indicate uneven ripening inside.

How to Cut a Watermelon

Cutting a watermelon doesn’t have to be messy. Here’s a simple step-by-step:

• Wash it: Rinse the whole watermelon under running water to remove dirt and bacteria from the rind.
• Trim the ends: Slice off both the stem and blossom ends to give yourself a stable cutting surface.
• Halve it: Stand it on one flat end and slice it in half lengthwise.
• Slice or cube:
  • For wedges: Place each half cut-side down and slice into triangle wedges.
  • For cubes: Score the flesh in a grid while still in the rind, then scoop out with a spoon or knife.
• Use a melon baller: For a fun touch, scoop out round balls for fruit salads or desserts.
• Store: Keep any unused portions in an airtight container in the fridge for up to 5 days.

How to Eat Watermelon

Watermelon is endlessly versatile. Here are some creative and classic ways to enjoy it:

• Fresh slices: Simple and refreshing—just cut and eat!
• Watermelon Feta Salad: Combine cubed watermelon with feta cheese, mint leaves, and a splash of balsamic vinegar for a sweet-savory summer dish.
• Juice: Blend chunks of watermelon and strain (optional) for a naturally sweet, hydrating drink. Add lime or mint for extra zing.
• Watermelon Smoothie: Blend watermelon with frozen strawberries, banana, or yogurt for a nutrient-packed smoothie.
• Watermelon Margarita: Mix watermelon juice, lime, tequila, and a touch of agave for a refreshing cocktail. Salted rim optional!
• Frozen treats: Puree and pour into molds for watermelon popsicles. Add kiwi or berries for color contrast and flavor.
• Pickled rind: Don’t toss the rind! Cook and pickle it for a tangy snack or sandwich topping.
• Roasted watermelon seeds: Dry and roast them for a nutty, protein-rich snack. Great with a little salt or spice.

Types of Watermelons

Did you know there are over 300 types of watermelons out there? Yep — these juicy, refreshing fruits aren’t just red and round anymore. From personal-sized minis to golden-skinned oddballs, there’s a watermelon for every taste and occasion. Here’s a quick breakdown of the main types you’ll come across:

Popular Watermelon Varieties

• Crimson Sweet: A classic seeded variety, known for its bright flavor and pretty striped rind. Weighs up to 25 lbs.
• Sugar Baby: Small and round, these weigh around 8–10 lbs. Perfect for fridge space and small households.
• Golden Midget: Turns gold on the outside when ripe — how cool is that? Inside, it’s all sweet pink flesh.
• Orangeglo: Big, oblong, and bursting with juicy orange flesh. Sweet and eye-catching!
• Moon and Stars: This one looks like the night sky, with yellow dots on dark green skin. Inside, it’s all juicy red.
• Harvest Moon & Excursion: Firm, sweet, and seedless — made for easy slicing and snacking.
• King of Hearts, Queen of Hearts, Millionaire: These royalty-named varieties are all seedless and bred for sugar-packed sweetness.

Other Fun Categories

• Picnic Watermelons: These are your big guys — perfect for family BBQs and parties (15–45 lbs).
• Icebox Watermelons: Smaller melons (5–15 lbs) that actually fit in the fridge. Sweet and handy.
• Heirloom & Specialty: Includes rare and unique types like Golden Honey, Kentucky Double Dwarf, and Little Baby Flower. These are great for gardeners and adventurous eaters!

How to Grow and Care for Watermelon

Growing watermelon is super rewarding—especially when you bite into a sweet, juicy slice you grew yourself. Here’s how to help your watermelon plants thrive from start to finish.

Site Selection and Sunlight

Choose a sunny spot—watermelons love warmth and need at least 6 to 8 hours of direct sunlight each day. And make sure there’s plenty of room—those vines like to spread out!

Soil Preparation

Watermelons prefer rich, well-draining soil. Sandy or loamy types are ideal, with a pH between 6.0 and 6.8. Mix in compost or well-rotted organic matter before planting. If you can, do a soil test to guide your fertilizer choices.

Planting Time

Wait until the soil warms up—at least 65 to 70°F (18–21°C)—and all chance of frost has passed. In cooler areas, you can use black plastic mulch or row covers to warm the soil and protect seedlings.

Planting Methods

Direct Seeding: Plant seeds 1–2 inches deep in mounds or rows. If using mounds, plant 4–6 seeds per mound, spaced about 4 feet apart. Thin to the two strongest seedlings once they sprout.

Transplants: Start seeds indoors 2–4 weeks before your last expected frost. Once the seedlings have 2–3 true leaves, transplant them outdoors, spacing them 2 feet apart in rows 4–6 feet apart.

Seedless varieties usually do better with transplanting, since their seeds are a little more delicate. Growing vertically? Stick to small varieties and use slings to support the fruit.

Spacing

Space plants about 3 to 5 feet apart, with rows 4 to 6 feet apart. That gives them plenty of room to grow and breathe.

Watering

Keep the water coming during flowering and fruit set. Water deeply and less frequently—around 1–2 inches per week is good. Let the soil dry slightly between waterings. Try to water at the base to avoid wetting the leaves. Once the fruit is maturing, cut back a little to boost sweetness.

Mulching

Early in the season, black plastic mulch warms the soil and blocks weeds. When the soil warms up to at least 75°F (24°C), you can add organic mulch like straw or grass clippings to keep moisture in and fruit clean.

Fertilizing

Watermelons are heavy feeders. Use a balanced fertilizer when planting, and add more nitrogen-rich fertilizer once vines start running and again at first bloom. But ease off on nitrogen later—it can grow more leaves than fruit if overdone.

Care and Maintenance

Keep young melons off the soil with straw or boards to prevent rot. Weed regularly, especially if you aren’t using mulch. Only prune if things get crowded—this is more useful for vertical growing.

Pollination

Bees do most of the pollinating, so avoid spraying insecticides when flowers are blooming. Good pollination is key to getting nice big fruit.

Temperature and Climate

Watermelons love the heat—ideal temps are around 80°F (27°C). They grow best in warm regions with long summers. Protect young plants from unexpected cold with covers or hot caps if needed.

Harvesting Tips

You’ll know your melon is ready when the little tendril near the fruit turns brown, the spot where it sits on the ground turns yellow, and the rind looks a bit dull. Watermelons don’t ripen after picking, so be sure to time it right!

How to Propagate Watermelon

From Seed

• Direct sow seeds in the garden after frost danger has passed and soil is warm (65°F+).
• Start seeds indoors 3–4 weeks early in biodegradable pots to minimize transplant shock.

Sowing Tips

• Depth: Plant seeds 1 inch deep in well-draining soil.
• Temperature: Ideal soil temperature for germination is 70–95°F (21–35°C).

Saving Seeds

• Use only heirloom or open-pollinated varieties.
• Rinse seeds from ripe fruit and dry thoroughly for storage.
• Store in a cool, dry place; viable for 4–5 years.

Common Pests and Diseases of Watermelon

Watermelons are pretty resilient, but they’re not immune to pest problems and plant diseases. Here’s a rundown of the usual suspects to keep an eye on while you grow your crop.

Pests

• Aphids: These soft-bodied insects suck sap from the plant, causing curled or yellowing leaves. They can also spread viruses and attract sooty mold.
• Cucumber Beetles: Striped or spotted, they munch on leaves and flowers and may transmit bacterial wilt.
• Armyworms and Rindworms: These caterpillars feed on leaves and fruit rinds, causing scars and damage.
• Spider Mites: These tiny pests hang out under leaves and cause speckled, yellowed damage and webbing.
• Whiteflies: Look for clusters under leaves. They suck sap and can spread viruses.
• Thrips: These tiny insects distort leaves and flowers and may carry viruses.
• Leafminers: Their larvae tunnel through leaves, leaving winding trails. Mostly cosmetic damage, but heavy infestations can be stressful to the plant.
• Cutworms and Wireworms: These soil pests attack young stems and roots.
• Others to watch: slugs, snails, leafhoppers, grasshoppers, and squash bugs.

Diseases

• Anthracnose: Look for brown, angular spots on leaves and sunken spots on fruits and stems. Loves wet, warm weather.
• Fusarium Wilt: Causes wilting, usually starting on one side of the plant. It also discolors the inner stem and roots.
• Gummy Stem Blight: Includes leaf spots, rot at the crown and fruit, and amber-colored ooze from lesions.
• Downy Mildew: Yellow mottled spots that turn brown, with leaves curling upward. Flares up in humid weather.
• Powdery Mildew: White powder on leaves that weakens plants and reduces fruit quality.
• Phytophthora Blight: Causes greasy-looking spots and white fuzzy growth. It thrives after heavy rains.
• Bacterial Fruit Blotch: Shows up as wet spots on fruit that crack and decay quickly.
• Also worth noting: Alternaria, leaf spots, damping off, and nematodes.

Management Strategies

• Rotate your crops every 3–4 years with non-cucurbits to reduce pest buildup.
• Choose disease-resistant watermelon varieties when available.
• Clean up after harvest—remove debris and old vines that might harbor pests.
• Water at the base of the plant to keep leaves dry and avoid fungal diseases.
• Use floating row covers early on to keep out bugs, but take them off at flowering so bees and butterflies can pollinate.
• Apply fungicides or insecticides as needed, and always follow local extension service guidance.
• Encourage helpful insects like ladybugs and hoverflies by growing pollinator-friendly plants nearby.

Watermelon FAQs

Is Watermelon a Fruit or a Vegetable?

Watermelon is botanically a fruit because it develops from the ovary of a flower and contains seeds. However, it’s also considered a vegetable in some contexts because it’s grown and harvested like other vegetables and belongs to the Cucurbitaceae family, which includes cucumbers, pumpkins, and squash. Fun fact: Oklahoma has even declared watermelon its state vegetable!

How Many Varieties of Watermelon Are There?

There are more than 300 varieties grown in the U.S. and South America, and over 1,200 worldwide. These come in different sizes, shapes, rind patterns, and flesh colors—including red, pink, yellow, and orange.

What’s the Difference Between Seeded and Seedless Watermelon?

Seeded watermelons are the traditional kind with black or brown seeds. Seedless types are hybrids—created by crossing plants with different chromosome counts. These are not GMOs and usually contain only tiny, soft white seed coats that are perfectly safe to eat.

Can You Eat Watermelon Seeds?

Yes! Both black and white watermelon seeds are edible. Black seeds are harder and usually pass through undigested, while white seeds are softer and partially digestible. Don’t worry—eating them won’t grow a watermelon in your stomach.

How Do You Pick a Ripe Watermelon?

• Look for a creamy yellow spot on the underside—this is the “field spot.”
• The rind should be dull, not shiny.
• It should feel heavy for its size.
• Tap it—a ripe melon sounds hollow.

How Long Does Watermelon Last?

Whole watermelons last about 3–4 weeks if stored cool and uncut. Once cut, refrigerate and eat within a few days.

Why Do Watermelon Plants Drop Flowers or Fruit?

This usually happens due to poor pollination, temperature extremes, inconsistent watering, or lack of nutrients. Supporting pollinators and maintaining consistent soil health and watering habits helps prevent this.

Should I Prune My Watermelon Plants?

Generally, pruning isn’t necessary and can reduce fruit production. But if the vines are out of control, light pruning is okay. For space-saving, consider training them on a trellis with smaller varieties.

Why Do Watermelons Split or Rot?

Splitting can occur from sudden rain after a dry period or heat stress, which builds up pressure inside the fruit. Blossom end rot, a type of rot on the bottom of the fruit, is often due to calcium deficiency or irregular watering.

How Often Should I Water Watermelon?

Watermelons love water—especially container-grown ones. Water daily when temperatures are under 80°F (27°C), and twice a day when hotter. In-ground plants do better with deep, infrequent watering.

Can Watermelon Ripen After Being Picked?

Nope! Watermelons don’t continue to ripen after harvest, so be sure to pick them when they’re fully ripe.

How Is Watermelon Used Around the World?

Watermelon is enjoyed in many ways: fresh, blended into juices or smoothies, and tossed into salads. In places like China, Russia, and parts of the U.S. South, the rind is pickled or even cooked as a vegetable.

Can Dogs Eat Watermelon?

Yes, dogs can safely enjoy watermelon in moderation! Just be sure to remove the seeds and rind, as they can be hard to digest or pose a choking risk. The juicy flesh is hydrating and low in calories—perfect for a summertime treat.

Can Cats Eat Watermelon?

Yes, cats can nibble on watermelon, but many may not be interested. Like with dogs, remove seeds and rind before offering it. It’s safe in small amounts and can be a fun way to give your cat a little hydration boost.

Is Watermelon Good for You?

Absolutely! Watermelon is low in calories but packed with vitamins A and C, antioxidants like lycopene, and lots of water to help keep you hydrated. It’s a refreshing, healthy snack, especially in the heat.

How Many Calories in Watermelon?

A one-cup (152 g) serving of diced watermelon has just about 46 calories. It’s a guilt-free, sweet treat that’s mostly water and natural sugar.

How to Tell If a Watermelon Is Ripe?

• Look for a creamy yellow spot on the bottom—the field spot.
• The rind should be dull, not shiny.
• It should feel heavy for its size.
• Give it a knock—it should sound deep and hollow.

When Is Watermelon Season?

Watermelon is typically in peak season during the summer—May through September in most areas. However, thanks to global production, you can usually find it year-round in supermarkets.

Can You Freeze Watermelon?

Yes! You can freeze watermelon chunks for smoothies or cold treats. Just know that the texture gets mushy once thawed, so it’s best used in blended drinks or frozen recipes rather than for snacking.

Does Watermelon Have Fiber?

It does, but only a little. One cup of diced watermelon has about 0.6 grams of fiber. It’s not a major fiber source, but every bit counts, especially when paired with other fruits and veggies in your diet.