When Should You Plant Sweet Potato Slips?
Set your conditions — the recommendation updates instantly.
GardenSays
Sow sweet potatoes outside May 19 – May 26 — after frost danger passes and soil has warmed.
- Sow from
- May 19 – May 26
- Last sowing
- May 28
- Last frost (typ.)
- May 5
Sweet potatoes are very frost-tender and germinate poorly in cold, wet ground — unlike peas or lettuce, you wait until AFTER the last frost (May 5) and until the soil warms. Sowing too early into cold spring soil rots the seed. The safe window in Minneapolis, MN opens around May 19.
Do this this week
- 1.Too late to sow sweet potatoes this year — the last sowing that could mature before frost was ~May 28
- 2.Plan next spring: sow from May 19 once soil is warm
Calculated result · 3 verified sources · Checked 2026-07-18 · How we decide
Why
Your season fits sweet potatoes comfortably — first sowings mature well before the typical first frost (Oct 5), and later sowings extend the harvest.
- Warm-season crops need warm soil to germinate: cold, wet spring ground causes seed rot and poor stands, which is why they go in after frost, not before.
- Days-to-maturity versus your frost-free season sets how late you can keep sowing.
When this doesn't apply
- Grown from vine cuttings ('slips'), not seed — plant after soil is reliably warm, well after frost danger. Clemson/NC State guidance (major sweet-potato-growing states) used since UMN's own coverage is minimal — Minnesota isn't a significant sweet-potato-growing region.
- A cold snap after sowing can still kill seedlings — hold off if a late frost is forecast, even inside the window.
How this was calculated
- 1. Last spring frostMay 5Source guidance
Minneapolis, MN: typical (50% probability) last 32°F frost
- 2. First sowing windowMay 19 – May 26Calculated result
Sweet potato is very frost-tender — sow only after frost danger passes AND soil has warmed (14-21 days after the last frost)
- 3. Last safe sowingMay 28Calculated result
90-120 days to maturity must finish ~10 days before the typical first fall frost (Oct 5)
Data sources
- Clemson Cooperative Extension — Home & Garden Information Center: Sweetpotatoes — Sweetpotatoes are grown from vine cuttings called 'slips.' Slips can be planted from May 1 through July 15 into raised mounds or rows set 3-4 feet apart, spaced 6-18 inches apart within the row, set 3-4 inches deep. Well-drained, sandy or loamy soil in full sun is ideal. About 90-120 days to harvest. (checked 2026-07-18)
- NOAA NCEI — 1991-2020 U.S. Climate Normals (freeze date probabilities) (checked 2026-07-15)
- National Gardening Association — frost date lookup (checked 2026-07-15)
What changes this answer
Your location
47 options — use the search field in the calculator above.
Starting from
Every change updates the answer, the math, the weekly steps and the share link instantly.
People also ask
When are sweet potatoes ready to harvest?
Sweet potatoes are ready when harvest before the first fall frost — in Minneapolis, MN, typically Aug 3 – Sep 16. Calculate yours →
Your next decisions
More planting dates tools: see all →