How to Grow Sweet Potatoes: From Slips to Harvest in Your Own Backyard
Sweet potatoes have been quietly staging a comeback in American gardens, and honestly, it's about time. While everyone's been obsessing over heirloom tomatoes and microgreens, this humble root vegetable has been waiting patiently for its moment—and that moment is now. Maybe it's because we've collectively realized that growing our own food isn't just trendy; it's practical. Or perhaps we've finally caught on to what Southern gardeners have known for generations: sweet potatoes are ridiculously easy to grow once you understand their quirks.
I'll admit, my first attempt at growing sweet potatoes was a spectacular failure. I treated them like regular potatoes (rookie mistake) and ended up with a patch of beautiful vines and exactly zero edible roots. That humbling experience sent me down a rabbit hole of agricultural extension publications and conversations with old-timers who've been growing these orange beauties since before I was born. What I learned transformed not just my sweet potato harvest, but my entire approach to gardening.
Understanding the Sweet Potato's True Nature
Sweet potatoes aren't potatoes at all—they're morning glories gone rogue. Seriously. Ipomoea batatas belongs to the same family as those twining flowers that take over your fence every summer. This explains so much about their behavior: the sprawling vines, the heart-shaped leaves, and most importantly, their absolute hatred of cold weather.
Unlike regular potatoes, which are stem tubers, sweet potatoes are storage roots. This distinction matters more than you might think. Regular potatoes form along underground stems, which is why you hill them up. Sweet potatoes develop from the plant's actual roots, which means they need different treatment entirely. They're also surprisingly nutritious—packed with beta-carotene, fiber, and enough vitamins to make a multivitamin jealous.
The plant originated in Central and South America, which tells you everything you need to know about its temperature preferences. These plants want heat, and lots of it. They laugh at 90-degree days while your tomatoes are wilting. In fact, sweet potatoes won't even think about forming roots until soil temperatures hit at least 65°F, and they really get going when it's closer to 80°F.
Starting with Slips: The Sweet Potato's Peculiar Propagation
Here's where sweet potatoes get weird. You don't plant seeds. You don't plant cut-up tubers like regular potatoes. Instead, you plant "slips"—shoots that sprout from mature sweet potatoes. It's like the plant decided to make things interesting just to keep us on our toes.
You can buy slips from garden centers (usually appearing around May in most areas), but growing your own is oddly satisfying and saves money. Plus, it gives you something to do during those late winter months when you're itching to get your hands dirty but it's still too cold outside.
To grow slips, you'll need a sweet potato—preferably organic, since conventional ones are sometimes treated to prevent sprouting. Around February or March (depending on your zone), suspend the potato halfway in a jar of water using toothpicks. Yes, like that avocado pit experiment everyone tries. Place it somewhere warm and bright—a kitchen windowsill works perfectly.
Within a few weeks, you'll see purple-tinged shoots emerging from the top and roots forming below. Once these shoots reach about 5-6 inches, twist them off with a gentle tug. Each shoot is a slip. Place these slips in their own containers of water to develop roots. When the roots are an inch or two long, they're ready to plant.
Some folks skip the water method entirely and bury sweet potatoes horizontally in moist potting soil, covering them with about 2 inches of soil. This method often produces more slips, but you can't watch the process unfold, which takes away half the fun if you ask me.
Preparing the Perfect Sweet Potato Bed
Sweet potatoes are surprisingly forgiving about soil, but they do have preferences. They want loose, well-draining soil—heavy clay is their nemesis. If your soil resembles modeling clay when wet, you'll need to amend it heavily or consider raised beds.
I've had my best success with raised beds filled with a mix of native soil, compost, and sand. The raised beds warm up faster in spring and provide the excellent drainage sweet potatoes crave. Plus, harvesting is infinitely easier when you're not trying to extract foot-long roots from compacted earth.
Sweet potatoes prefer slightly acidic soil (pH 5.8-6.2), but they're not prima donnas about it. If your soil is reasonably close to neutral, they'll manage. What they won't tolerate is excessive nitrogen. Too much nitrogen produces gorgeous vines and disappointing roots—learned that one the hard way after enthusiastically fertilizing my first crop.
Work in a balanced organic fertilizer before planting, something like 5-10-10. Sweet potatoes are efficient feeders and don't need much. In fact, in reasonably fertile soil, they might not need any fertilizer at all. The old-timers in my area swear by planting them in spots where beans grew the previous year, taking advantage of the nitrogen those legumes fixed in the soil.
Planting Time: Patience and Timing
Sweet potatoes have zero tolerance for frost. None. Zip. Even a light frost will damage the vines, and a hard freeze will kill them outright. Wait until all danger of frost has passed and soil temperatures are consistently above 65°F before planting. In my Zone 7 garden, that's usually mid-May, but I've learned to wait until Memorial Day just to be safe.
Plant slips about 12-18 inches apart in rows 3-4 feet apart. Those vines will spread—boy, will they spread. Bury the slips deep, leaving only the top leaves exposed. Unlike tomatoes, sweet potatoes won't form roots along the buried stem, but deep planting helps anchor them and puts the roots in consistently moist soil.
Water the slips well after planting and keep them moist for the first week or two. They'll look pathetic for a few days—wilted and sad—but don't panic. As long as the stems stay green, they're just adjusting to their new home. Once established, sweet potatoes are surprisingly drought-tolerant, though consistent moisture produces better yields.
The Long Growing Season
Sweet potatoes need time—lots of it. Most varieties require 90-120 days of warm weather to produce a decent harvest. This long season is why Northern gardeners often struggle with sweet potatoes. It's not that they won't grow in Maine or Minnesota; it's that the growing season is barely long enough to produce mature roots.
During the growing season, sweet potato vines will sprawl everywhere. And I mean everywhere. They'll cover paths, climb into neighboring beds, and generally act like they own the place. Some gardeners train them up trellises to save space, but I've found this reduces yields. Those vines root at nodes where they touch the ground, and these secondary roots help feed the plant.
Weeding is crucial early in the season, but once the vines take off, they'll shade out most competition. In fact, sweet potatoes make an excellent living mulch for areas you want to keep weed-free. Just remember where you planted them, because those vines can travel 10 feet or more from the original plant.
Water, Weather, and Weird Growth Habits
Sweet potatoes have some quirky water requirements. They need consistent moisture early in the season when vines are developing, then prefer things a bit drier as roots form. Too much water late in the season can cause roots to crack or develop an unpleasant texture. I usually stop watering entirely about 3-4 weeks before harvest unless we're in a serious drought.
Here's something nobody tells you: sweet potato vines are edible and quite tasty. In many Asian countries, the leaves are a common vegetable. You can harvest some leaves throughout the season without hurting your root production. Just don't go crazy—the plant needs those leaves to photosynthesize and feed the developing roots.
Pests rarely bother sweet potatoes, which is refreshing in the constant battle that is organic gardening. Deer might nibble the vines, and wireworms can be an issue in some areas, but generally, these plants sail through the season with minimal drama. The biggest "pest" I've encountered is voles, who seem to think I'm growing sweet potatoes specifically for their dining pleasure.
The Art of Knowing When to Harvest
Determining when to harvest sweet potatoes feels more like divination than science sometimes. The plants don't exactly announce when they're ready. The standard advice is to harvest before the first frost, but that's just the deadline, not necessarily the optimal time.
I start checking root development in late September by carefully digging around the edge of a plant. If I find good-sized roots (at least 2 inches in diameter), I know harvest time is near. The longer you leave them, the larger they'll grow, but there's a point of diminishing returns. Oversized sweet potatoes can be stringy and less flavorful than moderate-sized ones.
Some growers wait for the vines to start yellowing, but in my experience, this isn't a reliable indicator. My vines usually stay green right up until frost threatens. Soil temperature is a better guide—when nighttime soil temps start dropping below 55°F consistently, it's time to dig regardless of vine color.
Digging the Orange Gold
Harvesting sweet potatoes requires patience and a gentle touch. These roots can extend a foot or more from the plant's center and they bruise easier than a peach in a grocery store. Start digging at least a foot away from the plant's crown and work your way in carefully.
I prefer using a digging fork rather than a shovel—less chance of slicing through a prize specimen. Loosen the soil all around the plant first, then gently lift from below. It's like archaeological excavation, except your artifacts are edible.
Choose a dry day for harvest if possible. Wet soil clings to the roots and makes curing more difficult. As you dig, handle the roots like eggs. Every bruise and cut is an invitation for rot during storage. I learned this lesson after carelessly tossing my first harvest into buckets, only to lose half of them to soft rot within a month.
The Critical Curing Process
Here's the step that separates sweet potato success from failure: curing. Fresh-dug sweet potatoes taste starchy and bland. They need to cure to develop their characteristic sweetness and to heal any minor wounds from harvest.
Ideal curing conditions are 80-85°F with 85-90% humidity for 7-10 days. Unless you live in the Deep South, you probably don't have these conditions naturally in fall. I cure mine in a spare bathroom with a space heater and humidifier running. Some folks use a greenhouse or even a car parked in the sun (monitoring temperature carefully to avoid cooking them).
During curing, starches convert to sugars and the skin toughens, preparing the roots for long-term storage. The difference in flavor between cured and uncured sweet potatoes is dramatic—like the difference between a green tomato and a ripe one.
Storing Your Harvest
After curing, sweet potatoes need cool (55-60°F), dry, well-ventilated storage. A basement usually works well, though modern basements are often too warm. I store mine in mesh bags in my garage, which stays just about perfect through winter.
Never store sweet potatoes in the refrigerator. Cold temperatures cause a hard core to develop in the center and ruin the texture. They're tropical plants, remember? They want to stay cozy even in storage.
Properly cured and stored sweet potatoes will last 6-10 months. I've eaten sweet potatoes in April that I harvested the previous October, and they were still delicious. They do tend to get sweeter over time as starches continue converting to sugars.
Varieties Worth Growing
'Beauregard' is the standard recommendation, and for good reason. It's early (90 days), productive, and disease-resistant. But don't stop there. 'Georgia Jet' matures even faster (80 days), making it perfect for shorter seasons. 'Centennial' produces uniform roots that store exceptionally well.
For something different, try 'Purple Passion' or 'Japanese Purple', which have purple skin and white flesh with a nuttier, less sweet flavor. 'O'Henry' is a white-fleshed variety that tastes almost like a cross between a sweet and regular potato.
Bush varieties like 'Bush Porto Rico' are perfect for small gardens, producing shorter vines that won't take over your entire plot. Though I'll warn you—the yields are usually lower than vining types.
Final Thoughts from the Sweet Potato Trenches
Growing sweet potatoes has taught me patience in a way few other crops have. They're not flashy. They don't produce daily harvests like tomatoes or beans. For months, all you see are vines sprawling across the ground. But come fall, when you unearth those orange treasures, it feels like finding buried treasure in your own backyard.
The beauty of sweet potatoes lies in their simplicity once you understand their needs. Give them heat, time, and a little space to sprawl, and they'll reward you with pounds of nutritious, delicious roots that store better than almost any other garden crop. They're the quiet overachievers of the vegetable garden—undemanding, productive, and surprisingly versatile in the kitchen.
Start small your first year. Plant a dozen slips and see how they perform in your garden. Pay attention to their quirks, learn your soil and climate's influence on their growth, and adjust accordingly. Before long, you'll be that gardener giving away grocery bags full of sweet potatoes to anyone who'll take them, spreading the sweet potato gospel one root at a time.
Authoritative Sources:
Schultheis, Jonathan R., et al. Sweet Potato Production in North Carolina. North Carolina Cooperative Extension Service, 2015.
Smith, Tara, et al. Sweet Potato Production in Louisiana. Louisiana State University Agricultural Center, 2009.
Stoddard, C. Scott, et al. Sweet Potato Production in California. University of California Agriculture and Natural Resources Publication 7237, 2013.
United States Department of Agriculture. Sweet Potatoes: Planting, Growing, and Harvesting Sweet Potatoes. USDA National Agricultural Library, 2021.
Wilson, L. George, et al. Sweet Potatoes: Postharvest Handling and Storage. North Carolina State University Postharvest Technology Series, 2018.