How to Grow Sweet Potato Slips: The Art of Coaxing Life from a Humble Tuber

I still remember the first time I tried growing sweet potato slips. There I was, standing in my kitchen with a sweet potato from the grocery store, a glass of water, and absolutely no clue what I was doing. Three months later, I had more sweet potato plants than I knew what to do with. That journey taught me something profound about patience and the remarkable regenerative power hidden in what most people see as just dinner.

Sweet potatoes aren't actually potatoes at all—they're morning glories that decided to store their energy underground. And those slips? They're the bridge between last year's harvest and this year's abundance. Growing them yourself isn't just about saving money (though at $3-5 per slip at the garden center, that adds up). It's about understanding the cycle of growth in a way that buying pre-started plants never quite captures.

The Sweet Potato's Secret Life

Before we dive into the how-to, let me share something that changed my entire approach to growing slips. Sweet potatoes don't produce true seeds like tomatoes or peppers. Instead, they've evolved this fascinating method of cloning themselves through adventitious shoots—those slips we're after. Each slip is genetically identical to its parent, carrying forward all the characteristics that made that particular sweet potato worth growing in the first place.

This matters more than you might think. When I first started, I grabbed whatever sweet potato looked good at the store. Big mistake. Grocery store sweet potatoes are often treated with sprout inhibitors to extend shelf life. Some varieties slip readily; others fight you every step of the way. After years of trial and error, I've learned that organic sweet potatoes from farmers' markets or saved from your own harvest work infinitely better.

Starting Your Slips: Water Method vs. Soil Method

Most people default to the water method because it's what their grandmother did—suspend half a sweet potato in water using toothpicks, wait for magic. And yes, it works. But after growing slips for over a decade, I've become a convert to what I call the "lazy gardener's soil method."

With the water method, you're constantly monitoring water levels, dealing with rot if the water gets funky, and then you have to transplant those water-grown roots into soil—always a shock to the system. The toothpick suspension act gets old fast, especially when you're starting dozens of potatoes.

Instead, I lay my sweet potatoes horizontally in a shallow tray of moist potting soil, covering them about halfway. No toothpicks, no water changes, no drama. The potatoes stay happy, the developing slips already have their roots in soil, and I can ignore them for days at a time. Revolutionary? Hardly. But it works.

The key with either method is warmth. Sweet potatoes are tropical plants masquerading as temperate crops. They want temperatures between 75-80°F to slip properly. I learned this the hard way my first year, wondering why my kitchen-counter potatoes took two months to show any signs of life. Move them to the top of the refrigerator or near a heat vent, and suddenly you're in business.

Timing: The Make-or-Break Factor

Here's where most sweet potato growing articles get it wrong. They'll tell you to start your slips 6-8 weeks before your last frost date. Technically true, but woefully incomplete. Sweet potatoes need a long, warm growing season—90 to 120 days of it. More importantly, they need warm soil to thrive.

I start my slips in late February or early March, a full 12 weeks before our last frost date here in Zone 7. Why so early? Because sweet potato slips grow slowly at first, then explode with growth once they get going. By starting early, I have robust slips ready to plant when the soil temperature hits that magic 65°F mark, usually a full month after our last frost.

This timing issue trips up northern gardeners constantly. They start their slips on schedule, plant them out when the calendar says it's safe, and then watch them sulk in cold soil for weeks. Meanwhile, their southern neighbors who planted two weeks later in genuinely warm soil are already seeing vigorous growth.

The Slip Harvest: An Exercise in Patience

After 4-6 weeks (depending on temperature and variety), you'll start seeing shoots emerge from your sweet potatoes. This is where patience becomes crucial. Those first tender shoots are tempting, but resist the urge to twist them off immediately. Wait until they're 4-6 inches tall with a good set of leaves.

When you do harvest, don't just yank them off. Gently twist and pull the slip where it meets the potato. You want to get a bit of the heel—that swollen base where roots will form. Some people cut their slips, but I've found twisted-off slips root more reliably.

Here's a trick I stumbled upon by accident: after removing slips, don't toss that mother potato. Put it back in the soil or water. As long as it's not rotting, it'll produce another flush of slips. I've gotten three full harvests from particularly vigorous potatoes. It's like the plant world's version of a regenerating lizard tail.

Rooting and Hardening Off: The Forgotten Steps

Once you have your slips, you need roots. Drop them in a glass of water—no rooting hormone needed. Sweet potato slips want to grow; you just need to give them the opportunity. Within a week, you'll see white roots forming. Wait until these roots are 1-2 inches long before thinking about planting.

But here's what nobody tells you: those slips have been living in your cozy 75°F house for weeks. Plant them directly outside, and they'll go into shock faster than you can say "what happened to my plants?" Hardening off is crucial. Start by putting them outside in shade for a few hours, gradually increasing exposure over a week. Yes, it's a pain. Yes, it's worth it.

Planting Out: Setting Up for Success

Sweet potatoes are the teenagers of the garden—they want their space and lots of room to sprawl. Plant slips 12-18 inches apart in rows 3 feet apart. That seems excessive when you're tucking in those tiny slips, but trust me, by August you'll be wondering if you planted them too close.

Bury the slips deep, leaving only the top leaves exposed. Those buried nodes will develop additional roots, creating a stronger plant. I've experimented with planting at various depths over the years, and deep planting consistently produces better yields.

Soil preparation matters more than most people realize. Sweet potatoes prefer loose, well-draining soil with a slightly acidic pH (5.8-6.2). But here's the counterintuitive part: they don't want rich soil. Too much nitrogen produces gorgeous vines and tiny potatoes. I learned this lesson the hard way after amending a bed with fresh compost—I had sweet potato vines that could have doubled as groundcover for a mansion, but the harvest was pitiful.

The Growing Season: Benign Neglect with Benefits

Once established, sweet potatoes are remarkably self-sufficient. They're drought-tolerant once rooted, though consistent moisture produces better yields. The vines will sprawl everywhere, rooting at nodes and creating a living mulch that suppresses weeds.

Some people religiously lift and move the vines to prevent additional rooting, claiming it forces energy into the main potatoes. I've tried both ways, and honestly? The difference is minimal, and the work is substantial. Let them sprawl. Your back will thank you.

The only real maintenance is watching for pests. In my area, deer love sweet potato leaves (apparently, they're quite nutritious—some cultures eat them as greens). Voles can be problematic, tunneling in to nibble on developing tubers. But overall, sweet potatoes have fewer pest issues than regular potatoes.

Harvest: The Treasure Hunt

Harvesting sweet potatoes feels like digging for buried treasure, except you're guaranteed to find something. Wait for a dry day after the first light frost blackens the vines, or when the soil temperature drops below 55°F—whichever comes first.

Dig carefully. Sweet potatoes grow in unexpected directions and depths. I use a garden fork, starting a foot away from the crown and working inward. Every year I still manage to spear at least one potato, despite my best efforts. Consider it the garden tax.

Fresh-dug sweet potatoes taste terrible—starchy and bland. They need curing to convert those starches to sugars. Lay them out in a warm (80-85°F), humid place for 7-10 days. I use my garage with a space heater and damp towels. After curing, store them in a cool (55-60°F), dark place. Properly cured and stored, they'll last 6-10 months.

The Deeper Satisfaction

Growing sweet potato slips connects you to an older way of gardening, where saving and propagating your own plants was just what you did. There's something deeply satisfying about creating 20 or 30 plants from a single sweet potato, about working with the plant's natural tendencies rather than forcing it into some predetermined schedule.

More than that, it's a lesson in patience and observation. You learn to read the subtle signs—when a slip is ready to harvest, when roots are developed enough for planting, when the soil is truly warm enough. These aren't skills you can rush or fake. They develop over seasons, through small failures and unexpected successes.

I still remember that first successful crop, how amazed I was that those grocery store sweet potatoes had transformed into bushels of homegrown food. Now, every spring, as I set up my slipping trays, I'm reminded that gardening is as much about the process as the harvest. The slips are just the beginning of the story.

Authoritative Sources:

Bonnie Plants. "How to Grow Sweet Potatoes." Bonnie Plants, Bonnie Plants, LLC, 2023, bonnieplants.com/how-to-grow/growing-sweet-potatoes/.

North Carolina State Extension. "Sweet Potato Production." NC State Extension Publications, North Carolina State University, 2022, content.ces.ncsu.edu/sweet-potato-production.

Relf, Diane, and Alan McDaniel. "Sweet Potatoes." Virginia Cooperative Extension, Virginia Tech, 2021, www.pubs.ext.vt.edu/426/426-413/426-413.html.

Smith, Edward C. The Vegetable Gardener's Bible. Storey Publishing, 2009.

University of Georgia Extension. "Home Garden Sweet Potatoes." UGA Extension Circular 1014, University of Georgia, 2020, extension.uga.edu/publications/detail.html?number=C1014.