When to plant in St. John, IN
USDA Zone 6aEverything below — frost dates, hardiness zone, and what to plant when in St. John, Indiana — is derived from the closest NOAA station with complete climate normals.
Heads up: the nearest complete-normals station is about 19 km from St. John, so your yard's frost dates can differ — a low spot or a paved city center can shift them by a week. In zone 6a, St. John gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
Frost probability
PARK FOREST · 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 St. John’s own odds, recorded at PARK FOREST.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 24 | May 5 | Apr 20 | Sep 27 | Oct 10 | Oct 22 |
| 32°F | May 11 | Apr 23 | Apr 9 | Oct 6 | Oct 20 | Nov 1 |
| 28°F | Apr 27 | Apr 12 | Mar 30 | Oct 18 | Oct 30 | Nov 15 |
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 St. John, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 37 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.
St. John planting FAQ
When is the last spring frost in St. John, IN?
On average, the last spring frost in St. John is around April 23 (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 St. John, IN?
In St. John, the first 32°F freeze of fall lands around October 20 on average. Time your last harvests and any season-extension cover before it.
What hardiness zone is St. John in?
St. John is in USDA hardiness zone 6a. In zone 6a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in St. John?
St. John has about 180 frost-free days — a moderate growing season — between the average last spring frost (April 23) and first fall frost (October 20).
When should I plant tomatoes in St. John?
For St. John, sow tomatoes indoors about February 26–March 12 and move the seedlings out around April 30, after the last spring frost.
Never miss a window in St. John
An email when it’s time to start seeds, transplant, and sow — timed to St. John’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Schererville · 5 km
- Dyer · 7 km
- Cedar Lake · 8 km
- Griffith · 10 km
- Crown Point · 11 km
- Highland · 12 km
- Munster · 12 km
- Merrillville · 13 km
Frost dates recorded at PARK FOREST, 19 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 St. John, IN — Frost Dates & Zone 6a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00116616. Retrieved from https://blissgarden.com/indiana/st-john.