Sometimes I forget how much I love watermelon. Few things are more evocative of childhood summers than a slice of this iconic fruit served ice-cold with a sprinkling of salt.
You might be surprised to know how easy it is to grow watermelons in pots. The most important consideration is choosing the right sized container. Rachel and I have found that five-gallon containers are enough to support two vines, producing two 10-pound watermelons each. The nursery tag or seed packet will tell you the size of the fruit at maturity. Larger fruits would need to be grown in individual containers.
We like to grow most of our garden crops in containers because of the convenience. There’s no need for tilling or amending the topsoil. You can use a pre-packaged potting mix or simply add compost to well-rotted manure. At the end of the growing season we discard the vines and add the mix to our raised beds.
Watermelons are members of the cucurbit family, along with cantaloupes, pumpkins, cucumbers and squash. These annual fruits are native to Africa, but are cultivated throughout the world. They require daytime temperatures between 80 to 90 degrees in order to thrive.
They shouldn’t be planted until late spring because they have no tolerance for frost. Don’t wait too long to get them started. Watermelons need a long growing season, typically 80 to 100 days to reach maturity. Watermelons only ripen on the vine. If picked too soon, you’ll be stuck with a poor melon.
Place the containers where they will receive full sun and make sure they drain well. Give your watermelons plenty of room to sprawl. They can easily spread 15 to 20 feet, even in pots. They don’t put down additional roots as they sprawl, so you can place your containers on any surface. If limited space is an issue, you can train the vines to grow vertically on a balcony or trellis. You’ll need some sort of stretchable material to form a sling to support the weight of the growing fruit. Old pantyhose are well-suited for this purpose.
Watering is the trickiest thing about growing melons in containers. As the fruits are developing, they’ll need lots of water. Ideally, water twice a day until the watermelons are the size of a baseball and then once a day until mature. As they approach ripeness, reduce watering just enough to keep the soil moist to the touch. This will help to concentrate the sweetness. Over-watering produces bland tasting fruit.
As your watermelons grow, keep them from direct contact with the soil. This will help reduce rotting and fungal disease. Rachel and I let them rest on flat rocks or pieces of wood.
Judging ripeness can also be tricky. A deep-pitched thud when thumped is a good indication of ripeness. It takes a little bit of practice to get the hang of it. Another effective way to judge ripeness is to monitor the part of the rind that rests on the ground. It will turn from pale green or white to a more creamy yellow.
Lastly, the spirally tendril closest to the stem will dry up and even fall off. This isn’t the most accurate way to judge ripeness, but combined with one of the other two, it’s a good indication.
Nothing is more refreshing than a homegrown watermelon on a hot summer day.
Rachel and Ivan Minnis are avid gardeners. They live in Leavenworth. For more information, visit The Minnis Rose Garden on Facebook. Contact them at firstname.lastname@example.org