Nothing says summer like a sweet slice of watermelon. Interestingly, the original watermelons were quite bitter and were selectively bred to be sweet over the course of thousands of years. The ancestors of our modern watermelons were first cultivated in Africa and scientists have recently traced the genome back to a wild variety found in Libya and Sudan at least 6,000 years ago.
That’s a lot of generations of humans and their agricultural efforts to get us to our sweet and juicy modern watermelons! Luckily for the modern home gardener, growing watermelons is easier than ever. A few simple tips and tricks will help you grow the sweetest, juiciest watermelons you have ever tasted. It just takes a little bit of gardening know-how.
Let’s crack open the secrets to growing best watermelons this summer!
1. Turn Up the Heat
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As mentioned above, watermelons are native to the northern part of the African continent so they like it hot. The hotter the conditions, the sweeter your watermelons will be. Soil temperatures should be at least 65 degrees Fahrenheit (18.3 C) before you plant seeds or transplant any indoor-grown seedlings. You can check the top couple inches of soil with a soil thermometer to ensure proper conditions for good germination and healthy plants. This soil thermometer from Urban Worm is available on Amazon and has a large easy-to-read dial.
If you live in a cooler climateyou can increase the warmth of your watermelons by growing them under a floating row cover until temperatures are hot enough. Row cover fabric, our favorite is on Amazon, can be used with hoops or just laid directly over plants. If using a row cover, be sure to ventilate when air temperature reaches 80 degrees F (26.6 C), and remove the cover if temperature reaches 90 degrees F (32.2 C). Watermelons need at least 8 hours of direct sunlight to convert the sun’s energy into tasty fruit.
2. Banish Pests
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If your watermelon is destroyed by pests, it isn’t going to be juicy or sweet because you won’t be eating it! Common watermelon pests include aphids, armyworms, cucumber beetles, leaf miners, cutworms, crickets, darkling beetlesand spider mites. Your backyard wildlife might also try to take a bite of your melons (I’ve lost many to a family of groundhogs living under my shed). However, pest management needs to be thoughtfully applied because your watermelons rely on pollination by bees and other beneficial insects. Pesticides don’t discriminate between good bugs and bad bugs.
Using row covers early in the season can help keep pests off of watermelon seedlings, handpicking armyworms and other caterpillars from the plants is an easy daily task. You should also rotate your crops to reduce pests. It’s important to pay attention to plant types when rotating, too. Watermelons and cucumbers are both in the same family (Cucurbitaceae), so pests that were attracted to your cucumbers last year will attack your watermelons this year.
I have had success in keeping animals from taking a bite out of my watermelons by slipping the fruits into some old pantyhose. Pantyhose also make a great sling material to support melons that are growing from a trellis or need a lift off the ground. And even something as simple as placing a laundry basket upside down over the fruits and weighing it down with a brick will keep most animals at bay.
3. Give Them Space
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Watermelons need plenty of elbow room to grow big and sweet. Each plant needs at least 3 to 5 feet (1-1.5 m) of space. The bounteous leaves on your plant convert the sun’s rays into sugars in the fruit, so giving them room to grow will help you get the tastiest watermelon possible.
Planting watermelons too close to each other or other plants increases the likelihood of fungal infections on the leaves like powdery mildew and anthracnose. Your watermelon leaves and vines need good airflow to prevent fungal infections. You should also keep an eye on the bottom of your watermelons, if they sit on damp soil the fruit can develop belly rot. Place a thick layer of straw or wood mulch under the fruit to keep them from becoming too damp.
4. Proper Watering
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Watermelons are more than 90% water so they need to be watered deeply to be juicy and delicious. It is recommended to give watermelon plants 1 to 2 inches of water per week. A soaker hose buried under the mulch will help keep leaves dry and prevent fungal infections. You can find an affordable soaker hose from Walmart if you don’t already use one.
However, at the end of the season, everything changes. You should stop watering about a week before harvesting watermelons. This will concentrate the sweetness in the fruit and prevent it from bursting as it continues to ripen.
Proper watering, plant spacing, pest control, and growing conditions will ensure your watermelons will be filled with the sweetness of summer. Time to get growing!
