When to plant in Le Mars, IA
USDA Zone 5aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Le Mars, Iowa — all computed from Le Mars's nearest NOAA weather station.
In zone 5a, Le Mars gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
LE MARS · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Le Mars’s own odds, recorded at LE MARS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 22 | May 9 | Apr 28 | Sep 13 | Sep 27 | Oct 9 |
| 32°F | May 12 | Apr 30 | Apr 17 | Sep 21 | Oct 4 | Oct 19 |
| 28°F | May 2 | Apr 20 | Apr 5 | Sep 29 | Oct 16 | Oct 30 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Le Mars, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 35 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Le Mars planting FAQ
When is the last spring frost in Le Mars, IA?
On average, the last spring frost in Le Mars is around April 30 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Le Mars, IA?
Expect Le Mars's first fall frost near October 4 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Le Mars in?
Le Mars is in USDA hardiness zone 5a. In zone 5a, winters are cold — pick cold-hardy varieties and protect tender crops.
How long is the growing season in Le Mars?
Le Mars has about 157 frost-free days — a moderate growing season — between the average last spring frost (April 30) and first fall frost (October 4).
When should I plant tomatoes in Le Mars?
For Le Mars, sow tomatoes indoors about March 5–March 19 and move the seedlings out around May 7, after the last spring frost.
Never miss a window in Le Mars
An email when it’s time to start seeds, transplant, and sow — timed to Le Mars’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Sioux City · 36 km
- South Sioux City · 41 km
- Vermillion · 61 km
- Storm Lake · 81 km
- Spencer · 92 km
- Sioux Falls · 96 km
- Brandon · 96 km
- Yankton · 100 km
Frost dates recorded at LE MARS, 2 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Le Mars, IA — Frost Dates & Zone 5a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00134735. Retrieved from https://blissgarden.com/iowa/le-mars.