When to plant in Irmo, SC
USDA Zone 8bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Irmo, South Carolina — all computed from Irmo's nearest NOAA weather station.
Heads up: the nearest complete-normals station is about 17 km from Irmo, so your yard's frost dates can differ — a low spot or a paved city center can shift them by a week. In zone 8b, Irmo supports a wide range of perennials year-round; the frost dates above are what set your annual vegetable timing.
The average last spring frost in Irmo is now 9 days earlier than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
CEDAR CREEK 2E · 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 Irmo’s own odds, recorded at CEDAR CREEK 2E.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 4 | Apr 21 | Apr 7 | Oct 8 | Oct 20 | Nov 1 |
| 32°F | Apr 23 | Apr 10 | Mar 27 | Oct 15 | Oct 28 | Nov 8 |
| 28°F | Apr 14 | Mar 31 | Mar 9 | Oct 24 | Nov 5 | Nov 23 |
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 Irmo, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 20 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.
Irmo planting FAQ
When is the last spring frost in Irmo, SC?
Plan for the last spring frost in Irmo around April 10 (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 Irmo, SC?
The first fall frost in Irmo typically arrives around October 28 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Irmo in?
Irmo is in USDA hardiness zone 8b. In zone 8b, winters are mild — many tender perennials overwinter here.
How long is the growing season in Irmo?
Irmo has about 201 frost-free days — a moderate growing season — between the average last spring frost (April 10) and first fall frost (October 28).
When should I plant tomatoes in Irmo?
For Irmo, sow tomatoes indoors about February 13–February 27 and move the seedlings out around April 17, after the last spring frost.
Never miss a window in Irmo
An email when it’s time to start seeds, transplant, and sow — timed to Irmo’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Seven Oaks · 8 km
- St. Andrews · 10 km
- Lexington · 12 km
- Oak Grove · 14 km
- West Columbia · 15 km
- Red Bank · 20 km
- Forest Acres · 22 km
- Cayce · 22 km
Frost dates recorded at CEDAR CREEK 2E, 17 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 Irmo, SC — Frost Dates & Zone 8b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00381479. Retrieved from https://blissgarden.com/south-carolina/irmo.