How to Grow Sweet Potatoes: From Slips to Harvest in Your Own Backyard

I've been growing sweet potatoes for about fifteen years now, and I'll tell you something that might surprise you – they're probably the most forgiving crop I've ever worked with. Sure, they have their preferences (don't we all?), but once you understand what makes them tick, you'll be swimming in orange tubers come fall.

The first time I tried growing sweet potatoes, I made every mistake in the book. Planted them in heavy clay soil, watered them like tomatoes, and wondered why I got nothing but stringy roots and disappointment. But that failure taught me more than any gardening manual ever could.

Understanding the Sweet Potato's Soul

Sweet potatoes aren't actually potatoes at all – they're morning glories that decided to store their energy underground. This matters because it completely changes how you approach growing them. While regular potatoes are stem tubers from the nightshade family, sweet potatoes are true roots from the Convolvulaceae family. This distinction isn't just botanical trivia; it fundamentally affects everything from planting to harvest.

These plants evolved in Central and South America, where the soil drains fast and the sun beats down relentlessly. They're built for survival in conditions that would make other vegetables throw in the towel. I've seen sweet potato vines survive three weeks of drought that killed everything else in my garden, then bounce back like nothing happened once the rains returned.

The Art of Starting Slips

Here's where most people get intimidated, but starting your own slips is actually one of the most satisfying parts of the whole process. Around late February or early March (depending on where you live), I take a few organic sweet potatoes from the grocery store and get to work.

Some folks will tell you to suspend the potato half in water using toothpicks, like you're back in elementary school science class. That works, but I've found a better way. I lay my sweet potatoes horizontally in a shallow pan with about an inch of water, rotating them every few days. This method produces more slips and stronger ones too.

Within two to three weeks, you'll see purple and green shoots emerging from the eyes. These aren't just any shoots – they're your future plants. Once they reach about 5-6 inches tall with roots forming at their base, twist them off gently. Each potato can produce anywhere from 10 to 30 slips, depending on its size and your patience.

I learned the hard way that not all sweet potatoes will sprout. Some grocery stores treat their tubers to prevent sprouting, which is great for shelf life but terrible for propagation. If nothing happens after three weeks, you've probably got treated potatoes. Local farmers' markets or organic sections are your best bet for sproutable tubers.

Soil Preparation: Building the Perfect Home

Sweet potatoes are like that friend who says they're "easy-going" but actually has very specific preferences. They want loose, well-draining soil with a slightly acidic pH between 5.8 and 6.2. But here's the kicker – they'll still produce in less-than-ideal conditions, just not as prolifically.

I've grown decent sweet potatoes in everything from sandy loam (ideal) to amended clay (not ideal but workable). The secret with heavy soils is adding massive amounts of organic matter. I'm talking wheelbarrows full of compost, aged leaves, whatever you've got. One year, I mixed in so much shredded newspaper and grass clippings that my neighbor asked if I was building a compost pile or a garden bed.

The traditional method involves creating raised rows or mounds about 8-10 inches high. This isn't just garden aesthetics – it serves multiple purposes. The elevation improves drainage, the loose soil allows tubers to expand easily, and the increased surface area warms the soil faster in spring. Sweet potatoes are heat lovers, and warm soil is non-negotiable for good production.

Planting: Timing and Technique

Sweet potatoes laugh at frost. Well, they would if they could – instead, they just die. So timing your planting is crucial. I wait until soil temperatures hit a consistent 65°F, usually 2-3 weeks after the last frost. In my zone 7 garden, that's typically mid-May, but I've planted as late as early July and still gotten a decent harvest.

When planting slips, bury them deep – really deep. I plant them so only the top few leaves show above ground. This might seem extreme, but sweet potatoes form along the buried stem, so more underground stem equals more potential tubers. Space them about 12-18 inches apart in rows 3-4 feet apart. They need room to sprawl.

Water them in well, then... here's where I differ from conventional wisdom. Most sources tell you to water regularly for the first week. I water once, thoroughly, then leave them alone unless we're in a serious drought. This forces the roots to dig deep looking for water, establishing a stronger plant. I've lost maybe one slip in fifty using this method.

The Growing Season: Less is More

Once established, sweet potatoes are remarkably self-sufficient. The vines will spread like a verdant ground cover, sometimes reaching 10 feet or more. Some gardeners train them up trellises to save space, but I've found this reduces yield. Those sprawling vines aren't just showing off – where they touch the ground, they often root and form additional tubers.

Fertilization is where many gardeners go wrong. Sweet potatoes in rich soil with too much nitrogen will give you gorgeous vines and tiny tubers. I learned this the hard way my third year, when I side-dressed with compost mid-season and ended up with vines so lush they looked tropical, hiding a pathetic harvest of pencil-thin roots.

If your soil is reasonably fertile, skip the fertilizer entirely. If you must feed them, use something low in nitrogen and higher in phosphorus and potassium. I sometimes scratch in a bit of bone meal at planting, but honestly, my best harvests have come from beds I basically ignored all summer.

Water: The Goldilocks Principle

Sweet potatoes want their water just right – not too much, not too little. They need about an inch per week, including rainfall, but they're surprisingly drought-tolerant once established. The critical period is about 3-4 weeks before harvest when the tubers are bulking up. A deep watering then can make the difference between golf balls and softballs.

Overwatering, especially in heavy soils, leads to root rot and cracked tubers. I've pulled up sweet potatoes that looked like they exploded underground from too much late-season rain. On the flip side, severe drought stress can cause the tubers to become stringy and tough.

My approach? I water deeply once a week during dry spells, less if we're getting regular rain. About a month before harvest, I cut back watering unless we're in a serious drought. This helps the tubers cure in the ground and develop better flavor.

Pest and Disease Management: The Fortunate Few

Here's something that'll make you love sweet potatoes even more – they have relatively few pest problems. In all my years growing them, I've dealt with serious pest issues maybe twice. Wireworms can be a problem in new gardens or those recently converted from lawn. These annoying larvae bore holes through tubers, making them unmarketable but still edible (just cut out the damaged parts).

The main disease concern is black rot, which sounds scarier than it is. Good drainage and crop rotation usually prevent it. Don't plant sweet potatoes where you've grown them in the past 3-4 years. I rotate mine through a four-bed system with tomatoes, beans, and squash.

Deer love sweet potato vines, which I discovered when I found my patch mowed down to nubs one August morning. The plants recovered and produced fine, but now I spray with a homemade hot pepper solution when the deer pressure gets intense.

Harvesting: The Treasure Hunt

Harvesting sweet potatoes feels like digging for buried treasure, except you actually find something valuable. The timing can be tricky – they're ready anytime after the tubers reach usable size, usually 90-120 days from planting. But here's the thing: they keep growing until frost kills the vines or you dig them up.

I usually harvest in early October, before the first frost but after the tubers have had maximum time to size up. Some old-timers swear by harvesting after the first light frost blackens the vines, claiming it sweetens the tubers. I've tried both ways and honestly can't tell much difference.

The actual digging requires patience and a gentle touch. I start about a foot away from the crown and work my way in carefully. Sweet potatoes can grow surprisingly far from the mother plant – I once found a two-pounder nearly 18 inches away. Use a digging fork rather than a shovel to minimize damage. Even small nicks can lead to rot in storage.

Handle them like eggs. Seriously. Fresh-dug sweet potatoes have skin so thin you can scratch it with a fingernail. They need to cure before they develop that tougher skin you see in stores.

Curing and Storage: The Transformation

This is where sweet potatoes get really interesting. Fresh from the ground, they're starchy and not particularly sweet. The magic happens during curing, when enzymes convert starches to sugars and the skin toughens for storage.

Ideal curing conditions are 80-85°F with 85% humidity for 7-10 days. Unless you live in the tropics or have a controlled environment, perfect conditions are hard to achieve. I cure mine in my garage, where temperatures hover around 70-75°F in early October. I cover them loosely with newspaper to hold in some humidity. It's not textbook perfect, but it works.

After curing, store them somewhere cool (55-60°F), dark, and well-ventilated. Not refrigerator cold – that causes a hard core to develop and ruins the texture. My basement stays around 58°F, perfect for storage. Properly cured and stored sweet potatoes will last 6-10 months, though they're usually gone long before then in my house.

Varieties: Beyond the Grocery Store Orange

Most people only know the orange Beauregard types from the supermarket, but the sweet potato world is vast and varied. I grow at least four varieties each year, partly for insurance against crop failure but mostly because I'm curious.

'Georgia Jet' produces in just 90 days, perfect for shorter seasons. The tubers are red-skinned with deep orange flesh, and they're my go-to for consistency. 'Purple Passion' has purple skin and flesh, lower in sugar but with an almost nutty flavor that's incredible roasted. 'O'Henry' is white-fleshed and sweet, defying the assumption that only orange varieties taste good.

My current favorite is 'Murasaki', a Japanese variety with purple skin and white flesh. It's drier and denser than American types, almost chestnut-like when baked. I stumbled on slips at an Asian market and now grow them every year.

The Philosophy of Sweet Potato Growing

After all these years, I've come to see sweet potatoes as a metaphor for gardening itself. They teach patience – you plant slips in May and don't see results until October. They demonstrate resilience – neglect them, and they often thrive. They reward faith – you trust that beneath those wandering vines, something wonderful is happening underground.

I've also learned that the best gardening advice often runs counter to our instincts. We want to water, fertilize, and fuss over our plants. Sweet potatoes ask us to step back, to trust in their ancient wisdom. They've been feeding humans for thousands of years; they know what they're doing.

Every fall, when I dig that first hill and see those beautiful tubers nestled in the soil, I'm reminded why I garden. It's not just about the food, though a basement full of sweet potatoes provides serious food security. It's about participating in something timeless, about working with nature rather than against it.

So if you're thinking about growing sweet potatoes, stop thinking and start doing. Get some slips started this spring. Prepare a bed with whatever soil amendments you have on hand. Plant them after the soil warms, then basically ignore them until fall. You'll make mistakes – we all do – but sweet potatoes are forgiving teachers. And come October, when you're pulling up more tubers than you know what to do with, you'll understand why those of us who grow them can't imagine a garden without them.

Authoritative Sources:

Bonina, Justin, et al. Sweet Potato Production in the Southeastern United States. North Carolina State University Extension Publications, 2019.

Edmunds, Brooke A., et al. "Postharvest Handling of Sweet Potatoes." North Carolina Cooperative Extension Service, North Carolina State University, 2008.

La Bonte, Don R., et al. "Sweet Potato Production in Louisiana." Louisiana State University Agricultural Center, Publication 1980, 2020.

Loebenstein, Gad, and George Thottappilly, editors. The Sweetpotato. Springer, 2009.

O'Hair, Stephen K. "Tropical Root and Tuber Crops." Horticultural Reviews, vol. 12, 1990, pp. 157-196.

Schultheis, Jonathan R., et al. "Sweet Potato Production Guide for North Carolina." North Carolina Cooperative Extension Service, AG-678, 2015.

Smith, Tara P., et al. "Sweetpotato Viruses: 15 Years of Progress on Understanding and Managing Complex Diseases." Plant Disease, vol. 100, no. 11, 2016, pp. 2146-2159.

Villordon, Arthur, et al. "Development of a Simple Method for Estimating Sweet Potato Yield." HortTechnology, vol. 30, no. 1, 2020, pp. 137-143.