North Dakota · zones 4a–4a
When to plant sweet potatoes in North Dakota.
Sow or transplant between Jun 21 to Aug 5 in a typical year, keyed to North Dakota's median last frost around May 15. Dates below are state medians; your ZIP code shifts them by days to weeks.
The 2026 windows
Sweet Potatoes dates for a typical North Dakota season.
1 · Start indoors
May 10 to Jun 24
About 6 weeks before set-out. Warm spot, real light.
2 · Set out
Jun 21 to Aug 5
Keyed to the ~May 15 last frost. Sow 3" deep, 14" apart.
Harvest
~110 days later
~2.5 lb per plant over ~1 weeks.
North Dakota spans more than one climate: Zone 4 is the most common zone, but the state runs 4a to 4a. That's why the planner works from your ZIP code's frost dates, not your zone — mountain and coastal gardens in the same state can be three weeks apart.