You can definitely plant sweet potatoes in a window box, though you should keep in mind that your harvest will probably be on the smaller side. That said, sweet potatoes make absolutely gorgeous ornamental plants with lovely flowers. Beyond the standard edible types, there are even specific “ornamental” varieties known for their stunning foliage that look fantastic trailing out of a balcony planter.
Pick a Sunny Spot
One big plus of using a window box is that it’s easy to give your sweet potatoes the perfect environment. They absolutely thrive in warm, sunny spots. Their flexible vines are even pretty good at handling a bit of wind! Just keep in mind that the more sun they get, the more attention they’ll need from you.
Because sun leads to faster evaporation, you’ll need to be extra diligent about watering when they’re in a planter versus in the ground.
The Right Soil Mix
Sweet potatoes are hungry plants, so you’ll want a nutrient-rich potting mix. You also want something that holds onto moisture well so you aren’t stuck watering every hour.
A great DIY mix is high-quality vegetable soil blended with some fine lava granules or perlite. This creates a nutrient-dense home that stays hydrated. Just make sure the granules aren’t too chunky so the tubers have plenty of room to expand without hitting rocks.
Watering and Feeding
When you grow sweet potatoes in the garden, the vines often root into the ground as they crawl, picking up extra water and nutrients along the way. In a window box, they don’t have that luxury. They rely entirely on you for their “meals.”
During a summer heatwave, you might find yourself watering a couple of times a day. At the very least, give them a good soak early in the morning so they’re hydrated before the midday heat hits. To keep them lush, mix in some organic liquid fertilizer every two weeks. It’s the easiest way to feed and water at the same time!
Pruning and Maintenance
If your sweet potatoes are happy, those vines can easily reach several feet long. While they look beautiful draping down a balcony, they can get surprisingly heavy for some window box brackets. Don’t be afraid to give them a trim! Pruning actually encourages the plant to branch out, giving you a much fuller, bushier look.
In the fall, you can take cuttings from those vines to propagate new plants. Just pop the cuttings in a glass of water until they sprout roots, then pot them up. It’s a great way to get a head start on next year’s garden for free!
