Nothing rivals a slice of fresh, juicy watermelon on a sultry summer afternoon. Although they require a long growing season, it’s not as tricky to grow watermelons as you may think. In this article, you’ll learn how to grow watermelons in any climate and the best tips and tricks for getting a bountiful harvest of tasty melons.
Watermelons are vining plants with a sprawling growth habit. They’re native to the Kalahari Desert in Africa and belong to the Cucurbitaceae plant family with cantaloupe, cucumbers, gourds, pumpkins, and squash.
Watermelons are a delicious summertime treat, and they’re also highly nutritious. They’re a great source of plant-based fiber as well as vitamins A, C, and B1, B5, and B6.
Watermelon is also rich in antioxidants like carotenoids, lycopene, and cucurbitacin E, reducing inflammation, boosting eye and heart health, improving digestion, and promoting healthy skin and hair.
In addition, water-rich foods like watermelon keep you hydrated and help you feel full, assisting with weight loss.
- Tips and Tricks for Growing Watermelons
Tips and Tricks for Growing Watermelons
Unlike when you grow birdhouse gourds that take a long time until maturity, growing watermelons takes at least 70 days of warm weather (above 65℉) or longer, depending on the variety.
Gardeners in colder climates get a head start on the growing season by planting watermelon seeds indoors in early spring or purchasing nursery-grown seedlings after the last danger of frost has passed.
The ideal temperature for growing watermelon plants is between 65-90℉. They call for full sun, meaning at least six hours of direct sunlight each day.
Consistent soil moisture levels are also crucial to grow watermelons. The soil should remain moist but also have good drainage and never become waterlogged.
On average, watermelons need one to two inches of water per week. It’s helpful to use drip irrigation instead of overhead watering to avoid wetting the leaves, which increases the risk of your plants developing fungal diseases.
Pollination is essential for a fruitful watermelon crop. The plants each have separate male and female flowers and require the help of pollinators like bees and butterflies.
The male flowers have a stamen that generates pollen, and the female flowers have a pistil to receive pollen. Female flowers also have a small, swollen bulb at their base where the fruit eventually develops.
It’s advantageous to grow companion plants like aromatic herbs and flowers nearby to attract pollinating insects to your garden.
One of the best aspects of growing your own groceries is the ability to try unusual types of fruits and veggies that aren’t usually available at the grocery store or farmer’s market. Here are a few of the best watermelon cultivars for home gardeners.
How to Grow Watermelons from Seed
Since watermelons have a long growing season, most gardeners start seeds indoors about two or three weeks before the standard last frost date.
In warmer climates, plant seeds directly in your garden beds two weeks after the last danger of frost has passed, or whenever the soil temperature is regularly above 70℉. The optimal temperature for germination is around 80-85℉.
If you’re starting watermelon seeds indoors, you’ll require a few supplies. If you don’t already have them, these items are available at your local garden center.
Fill your seedling tray, peat pots, or an egg carton with a well-draining, nutrient-rich potting blend. It’s helpful to pre-moisten the soil so you don’t disturb the seeds after planting them.
Like when you plant cucumber seeds, sow the watermelon seeds a half-inch deep, then gently cover them with soil. Cover your tray with a humidity dome or sheet of plastic wrap to keep the soil moist during germination, which usually takes four to ten days.
It’s essential to keep the soil warm at all times. Watermelon seeds won’t germinate at temperatures lower than 70℉ or higher than 95℉.
Once the seedlings emerge, move the tray to a sunny windowsill that gets at least six hours of bright light every day, or use grow lights to prevent your seedlings from becoming elongated or “leggy” from not receiving enough sun.
Keep them well-watered, and rotate the tray every few days to promote strong stem growth.
Watermelon seedlings are highly temperature-sensitive and will die if exposed to below-freezing temperatures. Wait until two weeks after your typical last frost date before transplanting your seedlings or nursery-grown watermelon plants outdoors. The same goes for the best way to plant gourds, whether ornamental or edible.
Best Soil for Growing Watermelons
Watermelons thrive in rich soil that’s well-draining and contains ample amounts of organic matter.
Raise the soil temperature for your watermelons by covering your garden bed with a thick layer of dark-colored mulch, organic compost, or a sheet of black plastic a week or two before transplanting.
Like many other fruits and veggies, watermelons prefer a neutral to slightly acidic soil pH, between 6.0 and 7.0. Useful soil amendments include organic compost, well-aged manure, bone meal, or kelp meal.
Many growers plant watermelons in small hills or mounds to keep the soil warmer and ensure good drainage away from the plant’s main stem. Some gardeners even grow watermelons on a trellis to save ground space and promote better airflow.
While the smaller cultivars are ideal for trellising, with the proper support, it’s possible to train larger varieties to grow on a trellis, too. Watermelons don’t naturally climb and must be encouraged by loosely tying the stems to the lattice.
Eventually, the curly tendril growths on the vines begin wrapping themselves around the trellis. Support heavy fruits with sections of fabric tied to the framework like hammocks.
Choosing the Best Fertilizer for Watermelons
Watermelons tend to be heavy feeders and benefit from regular applications of organic fertilizer. There are three vital macronutrients present in plant fertilizer: nitrogen (N), phosphorus (P), and potassium (K).
Nitrogen boosts green leafy growth, phosphorus encourages robust roots, and potassium enhances fruiting and flowering. Use an all-purpose, organic fertilizer for the first four to six weeks.
Put two tablespoons of slow-release granular fertilizer into the bottom of each hole when transplanting your seedlings. Mix another dose of fertilizer into the soil around the base of the plant after four weeks.
Once your watermelons begin flowering, switch to a fertilizer with more phosphorus and potassium than nitrogen to support fruit production.
How Long do Watermelons Take to Grow?
We know they have a long growing season, but have you ever wondered, “Exactly how long do watermelons take to grow?” The answer is, it depends.
Some varieties, especially those that produce small, personal-sized watermelons, are faster to mature and produce fruit much sooner than other cultivars. On average, watermelons take between 70-110 days to reach maturity from the time seeds are planted.
Once the plant begins flowering, it typically takes about 45 days for the fruit to ripen. Keep in mind that watermelons don’t continue to ripen off the vine, so it’s critical not to pick them too early.
There are several indicators of a watermelon’s ripeness. The melon’s rind changes color with some varieties when it’s ready to be picked, or the stripes disappear.
Another reliable method to check for ripeness is gently pressing on the melon. If it’s still firm, wait a bit longer. If it gives a bit, it’s ready.
Additionally, observe the curly tendril growing from the nearest leaf node. If the tendril is still green, the melon isn’t ripe yet. Once the tendril dries out, the melon is mature.
Harvesting and Storing Homegrown Watermelons
Always use a sterile, sharp knife when harvesting your watermelons to avoid damaging the vines or main stem. Clean your tools between uses to prevent the spread of diseases between plants.
After harvesting, store uncut watermelons in your refrigerator for up to 10 days. They last for about four days after slicing them.
To preserve and keep watermelon fresh, tightly wrap any leftovers in plastic film or keep them in a sealed container and store cut watermelon in the crisper drawer of your refrigerator.
Remedies for Pest and Disease Problems
Closely monitor your watermelon plants for any signs of pest and disease issues. Healthy plants are far less susceptible to attacks from insects and pathogens. Your best defense is ensuring that your plants get adequate amounts of light, nutrients, and water.
Some of the most frequent insect pests that feed on watermelons include aphids, cucumber beetles, spider mites, and vine borers. After transplanting, cover the tender seedlings with row covers to prevent insects from laying eggs on the leaves.
If you notice an insect infestation, immediately spray all parts of the plant with an organic insecticide like neem oil or insecticidal soap.
Common fungal diseases that affect watermelon vines are anthracnose, fusarium wilt, powdery mildew, and stem blight. These diseases prosper in warm, humid conditions and frequently spread through water droplets.
Ensure that your plants have sufficient airflow, and use drip irrigation instead of overhead watering to keep the leaves dry. Treat affected plants with an organic copper or sulfur fungicide, and select disease-resistant varieties.
Companion Plants for Watermelons
Companion planting is a sensible garden design technique that utilizes favorable interactions between compatible plants.
Certain plants attract beneficial insects, repel garden pests, and enhance their neighbors’ flavor and overall vitality. However, some plants hinder one another’s growth and must live separately.
Marigolds, nasturtiums, and radishes are excellent companion plants for watermelons because they repel insect pests like cucumber beetles, whiteflies, and aphids. Alliums like chives, garlic, and onions deter whiteflies, spider mites, and aphids as well as deer and rodents.
Dill is extremely helpful around the garden, thanks to its ability to repel numerous insect pests, including aphids, cucumber beetles, and spider mites.
Dill also attracts beneficial predatory insects like hoverflies, ladybugs, lacewings, and parasitic wasps that help to control pest populations. Oregano repels cucumber beetles and attracts predators and pollinators, too.
Flowers like borage, calendula, chamomile, cosmos, and lavender bring pollinators to your garden. Some gardeners also plant a border of wildflowers to attract native bees.
Grow potatoes and sage away from your watermelons, as these plants stunt each other’s growth.
In addition, it’s best to avoid planting crops that are vulnerable to the same kinds of pest and disease problems nearby. Cucumbers are great companions for growing watermelon? It’s best not to grow watermelons near other melons, cucumbers, or squash.
Watermelons are a fun and delicious addition to your summer garden. Since they have a long growing season and need warm weather to germinate and produce fruit, it’s advantageous to plant watermelon seeds indoors in early spring.
There are countless unique varieties to choose from, so it’s possible to grow seedless watermelon, large or small fruits, and even orange and yellow watermelon cultivars.
If you enjoyed learning about growing watermelons, please share this article about how to grow watermelons with your fellow green thumbs on Facebook and Pinterest who might be wondering, “How long do watermelons take to grow?”