Plot · field guide
How to Grow Sweet Potatoes from Slips
Sweet potatoes are not grown from seed. They start from slips, which are rooted shoots pulled off a sprouted sweet potato. They need a long, warm season of about 110 days, but they are tough, they shrug off heat, and one plant returns about 2.5 pounds of roots. Here is the path from slip to a bin that keeps for months.
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Start with slips, not seed
A slip is a leafy shoot that sprouts off a sweet potato. You buy slips from a garden store or grow your own by setting a sweet potato in water or damp soil until it sends up shoots, then twisting those shoots off to root. Each slip becomes one plant.
You cannot plant a seed and get sweet potatoes. This is the part that trips up first-timers. Order or grow slips ahead of time so they are ready when the soil warms up.
- Slips are rooted shoots pulled from a sprouted sweet potato.
- Buy them or grow your own from a store-bought sweet potato.
- One slip grows into one plant, so count out how many you need.
Plant into warm soil
Sweet potatoes have zero cold tolerance and need a long warm season. Plant slips a few weeks after your last frost, once both the soil and the nights are warm. Cold, wet ground rots the slips before they take.
From planting, the roots need about 110 days to size up. Get them in the ground on time so they finish before your first fall frost. In a short-season area, that early start is the whole game.
- Plant a few weeks after your last frost, into warm soil.
- The crop needs about 110 days to mature.
- Cold, wet soil rots slips, so wait for warmth.
Space them and mound the soil
Give each slip room. Set slips 14 inches apart in the row, with 42 inches between rows. The vines run far and wide, so that row spacing is not wasted.
Plant into loose soil or raised mounds. Sweet potatoes size up in the top layer of soil, and loose ground lets the roots swell into big, clean shapes. Hard or rocky soil gives you small, twisted roots. A mound about 8 inches high also drains well, which these roots like.
- Space slips 14 inches apart, rows 42 inches apart.
- Plant in loose soil or a raised mound about 8 inches high.
- Loose ground means bigger, straighter roots.
Let them run, then dig before frost
Sweet potatoes need little fussing through summer. The vines sprawl and shade out most weeds on their own. Go easy on water and fertilizer late in the season, since too much nitrogen grows lush vines and skinny roots.
Dig the roots before your first fall frost. Frost kills the vines and cold, dead vines can rot down into the roots below. Loosen the soil with a fork well away from the plant so you do not spear the roots, then lift them by hand. A single plant returns about 2.5 pounds, and can run from 1.5 to 4 pounds depending on your soil and season.
- Dig before the first fall frost so cold vines do not rot the roots.
- Loosen with a fork away from the plant to avoid spearing roots.
- Expect about 2.5 pounds per plant, sometimes up to 4.
Cure them, then store for months
Fresh-dug sweet potatoes are not sweet yet and do not store well. They need to cure. Hold them somewhere warm and humid, about 80 F, for 10 to 14 days. Curing heals the skin and turns some of the starch to sugar, so they taste better and keep far longer.
After curing, move them somewhere cool, dark, and dry to store. Do not put them in the fridge, which turns them hard and off-flavored. Cured and stored right, sweet potatoes keep for months, so a fall harvest feeds you deep into winter. Keep them off a cold floor in a breathable bin or basket, not a sealed bag.
- Cure 10 to 14 days somewhere warm and humid, about 80 F.
- Store cool, dark, and dry after curing, never in the fridge.
- Cured roots keep for months in a breathable bin.
Keep going
Questions, answered straight
Yes. Set a sweet potato in water or damp soil until it sends up leafy shoots, then twist those shoots off and root them. Each rooted shoot is a slip, and each slip grows into one plant. You cannot grow them from seed.
About 110 days from planting slips to harvest. They need that long, warm season, so plant a few weeks after your last frost and dig before your first fall frost.
Fresh-dug roots are starchy and store poorly. Curing them at about 80 F for 10 to 14 days heals the skin and turns starch to sugar. Cured roots taste sweeter and keep for months instead of weeks.
About 2.5 pounds of roots per plant, and anywhere from 1.5 to 4 pounds depending on your soil and season. Loose soil and a full warm season push you toward the high end.