Bismarck, ND · zone 4a · ~139 frost-free days
When to plant in Bismarck: frost dates and zone 4a.
In Bismarck, the typical last spring frost lands around May 12 and the first fall frost around Sep 28, giving you about 139 frost-free days. Cool-season crops go out before the last frost; warm-season crops wait until after it.
The 2026 windows
Sow dates for Bismarck, keyed to your frost.
| Crop | Start indoors | Spring sow / set out | Fall sow |
|---|---|---|---|
| Tomato, slicing | Apr 7 to May 22 | May 19 to Jul 3 | — |
| Lettuce, leaf | — | Apr 4 to May 19 | Jul 15 to Sep 13 |
| Carrot | — | Apr 4 to May 7 | Jul 3 to Jul 29 |
| Bush Bean | — | May 12 to Jul 2 | — |
| Cucumber, slicing | — | May 19 to Jul 12 | — |
| Pepper, bell | Apr 16 to May 25 | May 28 to Jul 6 | — |
| Kale | Feb 21 to Mar 21 | Apr 4 to May 2 | Jun 28 to Aug 13 |
| Spinach | — | Mar 21 to May 2 | Jul 15 to Sep 2 |
Bismarck sits in Zone 4a, but two gardens in the same city can be a week or two apart. The planner works from your ZIP code's frost dates, not the zone, so the dates land right for your block, not the metro average.
Build your Bismarck garden plan.
Tell the free planner what you want to eat and who you're feeding. It returns plant counts, spacing, and frost-safe sow dates for ZIP 58501 in about 60 seconds.
Bismarck planting questions
What planting zone is Bismarck, ND?+
Bismarck is in USDA hardiness zone 4a. Growing zone, gardening zone, and planting zone all mean the same thing: the USDA number, 4a here. It tells you what survives winter, not when to plant. Frost dates set your planting time, and the free planner uses your exact ZIP code's frost dates, which can differ by weeks across one metro.
When is the last frost date in Bismarck?+
The typical last spring frost in Bismarck, ND is around May 12. That is an average from local history, not a guarantee, so tender crops like tomatoes and peppers are safer with a week of buffer after it.
When is the first frost date in Bismarck?+
The typical first fall frost in Bismarck, ND arrives around Sep 28, closing a growing season of roughly 139 frost-free days. Count backward from it to find the last date a fall crop can still finish.
What can I plant now in Bismarck?+
It depends on the date. Cool-season crops like lettuce, kale, and spinach go out weeks before the last frost; warm-season crops like tomatoes and peppers wait until after May 12. The table above shows each crop's window; the free planner turns your ZIP into an exact, dated calendar.