Springtime Gardening: Let’s Talk Watermelons!
Gardeners like you must be very excited that spring has finally arrived—I know I am! I can’t wait to get outside and discover all the surprises popping up in the garden. Seedlings are sprouting, spring flowers are blooming, and with temperatures on the rise, it’s the perfect time to grow juicy watermelons.
History of Watermelons
Did you know that watermelons are ancient fruits that have been cultivated since prehistoric times? They originally grew wild in the Kalahari Desert in Africa, though those early fruits weren’t sweet like the ones we enjoy today. Watermelons have even been discovered in Egyptian tombs at various archaeological sites, showing how far back their cultivation goes.
Through selective breeding and agricultural advancements, those bitter green fruits evolved into the sweet, red-fleshed melons we know now. Seedless watermelons were first developed by Japanese scientist Professor H. Kihara.
Ideal Growing Conditions
Watermelons thrive in tropical and temperate climates. Last year, I grew baby watermelons in a 17-gallon container using a simple homemade trellis. Summers in my area are harsh, with temperatures consistently over 100°F, which can be challenging even for heat-loving plants like watermelons. But with some shade and vertical growing, I had a sweet and refreshing harvest.
The benefits of growing watermelons in containers
- You can control the amount of space it occupies and also the amount of water. Watermelons like consistent watering. Perfectly watered watermelons are sweeter in taste with juicy pulp.
- Also, you can protect the plants better by covering them using either a tarp or shade clothe during constant rain and extreme summer heat if the plant is contained.
- Keeping watermelon plants potted and growing them vertically also saves a lot of space. Planting them in the ground occupies a considerable amount of space since if grown directly in the ground the recommended spacing between two plants is about 6 feet. If you have a big yard then it is not a problem but for urban gardeners, potted plants work the best.
- The plant is a creeping branching vine. The tendrils are the coiled structures that easily grab onto the trellis helping the vine grow upwards. With the plants wrapping around on the trellis, a beautiful vertical structure can be created in the garden. The vines still can get unruly like a toddler and try to wrap onto the branches of the adjacent plants. So you may need to keep guiding them and if you choose a big fruit variety you may even need to support the fruit to ensure that it doesn’t break off of the vine.
- When grown vertically in containers, it is easier to protect fruits from animals. I have seen a friend of mine was growing watermelon and rodents used to nibble on the fruits.
Benefits of Growing Watermelons in Containers
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Space Control: Growing in containers helps manage how much space and water the plant uses. Watermelons love consistent watering, and when done right, they turn out sweeter and juicier.
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Weather Protection: It's easier to shield potted plants from heavy rain or intense heat using tarps or shade cloth.
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Efficient Use of Space: When grown vertically, watermelon vines wrap around trellises using their tendrils, creating a charming vertical structure. This method is especially ideal for urban gardeners.
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Pest Prevention: Elevating the fruits makes it harder for animals like rodents to nibble on them.
Just be aware: watermelon vines can get a little wild and try to tangle with nearby plants. If you’re growing a larger fruit variety, you may need to support the fruit to prevent it from snapping off the vine.
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Growing Watermelons in the Ground
When planted in the ground, watermelon vines act like living mulch, helping retain soil moisture. However, the fruits may need protection from moisture damage—placing them on straw, cardboard, or fruit stands can help.
Growing in-ground allows the plant to spread out, often leading to bigger yields and the ability to grow larger varieties.
Why Choose a Small Fruit Variety?
If you're growing in containers, go for a small-fruit variety like baby watermelons. They mature faster and are more manageable for smaller households. You also won’t have to deal with leftovers or overindulging in sweet fruit.
Soil, Sun, and Temperature Needs
Watermelons prefer well-draining, sandy loam soil with a slightly acidic pH of 6–7. They're sun-loving plants that thrive in heat.
They are not cold-tolerant. Below 50°F, they may survive, but the fruits won’t mature. The optimal growing temperature is between 65–95°F.
I live in Zone 8, Texas, where summers are brutally hot. Watermelons do best here in early spring to early summer, and again from late summer to early fall. During peak heat, the leaves may yellow and wilt, but the plants bounce back as temperatures cool.
Watering Tips
Watermelons need lots of water and nutrients to support their vigorous growth. I regularly prune leaves during summer to redirect energy toward fruit development.
When to Start New Plants
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Short Summers: Start seeds indoors 6–8 weeks before your region hits 70°F.
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Direct Sowing: Plant seeds outdoors 2–3 weeks after the last frost, once the weather is consistently warm.
Watermelons typically take about 80 days to mature, though larger varieties may take longer.
Optimal Temperature
They are not at all cold tolerant. They do not well when the temperature drops down to 50°F and below. At these lower temperatures, plants may survive but the fruit doesn’t mature. The optimal temperature for growth is 65–95°F. I live in Texas where summers are exceptionally hot and the temperatures are in the mid to high hundreds and it is normal to have heat waves lasting up to a week or more at a time. In my zone, ie zone 8, Watermelon plants do well from spring-early summer and then again late summer-early fall in my region. During the extreme heat of summer, the leaves start drying up and turn yellow. You might even feel that they are not going to survive the summer but they recover as soon as the temperature starts dropping down.
Watering Needs for Watermelons
Watermelons need a good amount of water and nutrients to keep growing as they also grow a lot of foliage too. During summertime, I keep pruning the leaves to divert all the nutrition towards growing fruits.
When to Start the New Plants
Now let’s see when to start the plants. If you have a short summer in your region then you can start the seedlings indoors in late winter, about 6–8 weeks before the temperature in your region reaches about 70°F. At that time they will be ready for transplanting outdoors.
Or start the plants directly outdoors 2–3 weeks after the danger of the frost is over and the temperature is consistently warm. The seed to harvest time for watermelon is approximately 80 days. It is longer for the bigger varieties.
What to feed the plant to get the best fruits?
In the initial period, I want the plant to mature faster so I feed fish fertilizer every 2 weeks for a couple of months and also when I transplant the plants in the final spot I add a mixture of blood and bone meal to provide both nitrogen and phosphorus so that the fruit-bearing and maturation occurs. I also add some azomite to give my plants complete nutrition. The blood and bone meal are long-term fertilizers and I start seeing their result in about 2 months after the application. I frequently feed some compost to my plants.
Are Watermelons Annual or Perennial Plants?
Watermelons are annual plants so you have to start them every year. They can easily be grown from seeds. Unlike a longer growing period, germination time is much shorter, usually between 3–10 days. You can see healthy seeds sprouting only in a couple of days. This year, I’ve decided to grow some of the germinated plants in a raised bed. I’m still planning to grow them vertically though.
Parts of the Watermelon Plant
Roots
Watermelon has a taproot system and the roots are delicate. It matters more when you grow the seedlings in some pot and then try to transfer it in the ground. They can easily get damaged especially while separating the seedlings and if you are not gentle with them while planting.
Leaves
The leaves are partitioned into several parts and look very attractive. But they also attract several pests like aphids, cucumber beetle and several other. Beneficial insects play a key role in taking care of the plants in a safe way. I keep removing the dead and yellow leaves during summertime to reduce the energy needs of the plant.
The stems are covered in hairy structures and they branch. They also have coiled structures on their stems called tendrils that help the plant get support.
Flowers
Flowers start developing after about a couple of months. At first predominantly male flowers develop and once the plant is mature enough to bear fruits, both female and male flowers appear. It is not hard to distinguish between male and female flowers. female flowers have a small fruit-like structure under the flower. If the pollination is successful this tiny fruit becomes a mature fruit. It takes another 1 1/2- 2 1/2 months for the fruits to get ready for the harvest.
How do you know that the watermelons are ready for picking?
It can be tricky to know if the watermelon is ready to be picked or not. If you wait too long then the fruit might fall off from the vine or if picked early, it may not reach its maximum level of sweetness. I keep checking on the fruits mainly the tendril near it. Once the tendril turns brown, you can harvest the fruit. Waiting longer even after the harvest makes the watermelon much