When to plant in Portsmouth, OH
USDA Zone 7aHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Portsmouth, Ohio — all computed from Portsmouth's nearest NOAA weather station.
Zone 7a means many perennials and even some tender shrubs overwinter in Portsmouth, while your frost dates still decide when annuals go out.
Frost probability
PORTSMOUTH-SCIOTOVILLE · 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 Portsmouth’s own odds, recorded at PORTSMOUTH-SCIOTOVILLE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 15 | Apr 30 | Apr 13 | Oct 3 | Oct 15 | Oct 27 |
| 32°F | May 5 | Apr 17 | Apr 3 | Oct 11 | Oct 25 | Nov 6 |
| 28°F | Apr 20 | Apr 4 | Mar 19 | Oct 21 | Nov 4 | Nov 18 |
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 Portsmouth, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 29 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.
Portsmouth planting FAQ
When is the last spring frost in Portsmouth, OH?
Portsmouth's average last spring frost falls near April 17 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Portsmouth, OH?
The first fall frost in Portsmouth typically arrives around October 25 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Portsmouth in?
Portsmouth is in USDA hardiness zone 7a. In zone 7a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Portsmouth?
There are roughly 191 frost-free days in Portsmouth (a moderate growing season), running from the average last frost around April 17 to the first fall frost near October 25.
When should I plant tomatoes in Portsmouth?
In Portsmouth, start tomato seeds indoors around February 20–March 6, then transplant seedlings outdoors around April 24 once the danger of frost has passed.
Never miss a window in Portsmouth
An email when it’s time to start seeds, transplant, and sow — timed to Portsmouth’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Ironton · 34 km
- Ashland · 42 km
- Huntington · 59 km
- Chillicothe · 65 km
- Circleville · 94 km
- Teays Valley · 95 km
- Washington Court House · 96 km
- Athens · 97 km
Frost dates recorded at PORTSMOUTH-SCIOTOVILLE, 5 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 Portsmouth, OH — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00336781. Retrieved from https://blissgarden.com/ohio/portsmouth.