When to plant in Highland, IL
USDA Zone 6bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Highland, Illinois — all computed from Highland's nearest NOAA weather station.
Highland's nearest full-normals station sits about 31 km out, so treat these as a close estimate — local microclimate can nudge your first and last frost. In zone 6b, Highland gardeners can grow many hardy perennials, while the last and first frost still dictate the annual vegetable calendar.
The average first fall frost in Highland is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
BELLEVILLE SIU RSCH · 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 Highland’s own odds, recorded at BELLEVILLE SIU RSCH.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 8 | Apr 23 | Apr 10 | Sep 27 | Oct 9 | Oct 23 |
| 32°F | Apr 28 | Apr 12 | Mar 28 | Oct 3 | Oct 20 | Nov 1 |
| 28°F | Apr 16 | Mar 31 | Mar 14 | Oct 15 | 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 Highland, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 42 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.
Highland planting FAQ
When is the last spring frost in Highland, IL?
Plan for the last spring frost in Highland around April 12 (the date it has a 50% chance of a 32°F freeze). Anything frost-sensitive should go out after it.
When is the first fall frost in Highland, IL?
The first fall frost in Highland typically arrives around October 20 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Highland in?
Highland is in USDA hardiness zone 6b. In zone 6b, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Highland?
Highland has about 191 frost-free days — a moderate growing season — between the average last spring frost (April 12) and first fall frost (October 20).
When should I plant tomatoes in Highland?
For Highland, sow tomatoes indoors about February 15–March 1 and move the seedlings out around April 19, after the last spring frost.
Never miss a window in Highland
An email when it’s time to start seeds, transplant, and sow — timed to Highland’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Troy · 19 km
- Glen Carbon · 26 km
- Edwardsville · 26 km
- O'Fallon · 27 km
- Collinsville · 30 km
- Shiloh · 31 km
- Fairview Heights · 34 km
- Wood River · 35 km
Frost dates recorded at BELLEVILLE SIU RSCH, 31 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 Highland, IL — Frost Dates & Zone 6b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00013802. Retrieved from https://blissgarden.com/illinois/highland.