In Harrisburg, PA, the average last spring frost is Apr 9 and the average first fall frost is Nov 2, which leaves about 206 frost-free days for the garden. These dates come from NOAA climate normals for the Middletown Harrisburg International Airport, PA weather station, at 312 feet above sea level.
A long season lets you do more than one planting: a spring crop, a second planting of quick crops in summer, and a fall garden. Succession planting works well here. Frost timing varies from year to year: in about 1 spring in 10 the last frost falls as late as Apr 25, and in about 1 fall in 10 the first frost arrives as early as Oct 18.
Frost dates for Harrisburg, PA
| Chance of a freeze (32°F) after or before this date | Last spring frost | First fall frost | Freeze-free season |
|---|---|---|---|
| Optimistic (about 1 year in 10) | Mar 28 | Nov 15 | 232 days |
| Average (half of years) | Apr 9 | Nov 2 | 206 days |
| Cautious (9 years in 10 are safe) | Apr 25 | Oct 18 | 176 days |
Source: NOAA NCEI U.S. Climate Normals, 1991 to 2020. Use the cautious dates for tender crops such as tomatoes and peppers.
When to plant in Harrisburg, PA
These windows count weeks forward and back from the average frost dates above. They are planning guides: check the forecast before planting tender crops, and see our what to plant now tool for today's date.
| Crop | Start seeds indoors | Plant outdoors in spring | Plant in fall |
|---|---|---|---|
| Tomatoes | Feb 12 to Feb 26 | Apr 16 to Apr 23 | – |
| Peppers | Jan 29 to Feb 12 | Apr 23 to Apr 30 | – |
| Eggplant | Jan 29 to Feb 12 | Apr 23 to Apr 30 | – |
| Onions | Jan 29 to Feb 12 | Mar 12 to Mar 26 | – |
| Parsley | Jan 29 to Feb 12 | Apr 9 to Apr 16 | – |
| Broccoli, cabbage, cauliflower | Feb 12 to Feb 26 | Mar 26 to Apr 2 | Aug 10 to Sep 7 |
| Basil | Feb 26 to Feb 26 | Apr 16 to Apr 23 | – |
| Peas | Sow outdoors | Feb 26 to Mar 12 | Aug 10 to Sep 7 |
| Spinach | Sow outdoors | Feb 26 to Mar 12 | Sep 7 to Oct 5 |
| Radishes | Sow outdoors | Feb 26 to Mar 12 | Sep 7 to Oct 5 |
| Lettuce | Sow outdoors | Mar 12 to Mar 26 | Sep 7 to Oct 5 |
| Carrots | Sow outdoors | Mar 12 to Mar 26 | Aug 10 to Sep 7 |
| Beets | Sow outdoors | Mar 12 to Mar 26 | Aug 10 to Sep 7 |
| Potatoes | Sow outdoors | Mar 12 to Mar 26 | – |
| Kale | Sow outdoors | Mar 12 to Mar 26 | Aug 10 to Sep 7 |
| Swiss chard | Sow outdoors | Mar 26 to Apr 9 | – |
| Cilantro | Sow outdoors | Mar 26 to Apr 9 | Sep 7 to Oct 5 |
| Dill | Sow outdoors | Apr 9 to Apr 16 | – |
| Bush beans | Sow outdoors | Apr 16 to Apr 23 | Jul 30 to Aug 13 |
| Pole beans | Sow outdoors | Apr 16 to Apr 23 | – |
| Sweet corn | Sow outdoors | Apr 16 to Apr 23 | – |
| Cucumbers | Sow outdoors | Apr 16 to Apr 23 | Jul 20 to Aug 3 |
| Zucchini and summer squash | Sow outdoors | Apr 16 to Apr 23 | Jul 30 to Aug 13 |
| Winter squash | Sow outdoors | Apr 16 to Apr 23 | – |
| Sweet potatoes (slips) | Sow outdoors | Apr 23 to May 7 | – |
| Okra | Sow outdoors | Apr 23 to May 7 | – |
A dash in the fall column means the crop is not usually planted in fall, or the season is too short.
Overnight lows this week
The National Weather Service forecast shows frost risk on: Sun 15 night (32°F), Mon 16 night (30°F), Tue 17 night (33°F), Wed 18 night (32°F). Cover tender plants before dark on those nights.
| Night | Forecast low | Frost risk |
|---|---|---|
| Sat 14 night | 37°F | No frost expected |
| Sun 15 night | 32°F | Freeze |
| Mon 16 night | 30°F | Freeze |
| Tue 17 night | 33°F | Frost possible |
| Wed 18 night | 32°F | Freeze |
| Thu 19 night | 37°F | No frost expected |
| Fri 20 night | 39°F | No frost expected |
Live forecast for the station location, from the National Weather Service. For your own ZIP code, use our garden weather forecast.
More garden tools for Harrisburg, PA
- Frost dates by ZIP code for your exact location
- What to plant now, based on today's date
- Garden weather forecast by ZIP code
- Safe transplant date calculator
Frequently asked questions
When is the last frost in Harrisburg, PA?
The average last spring frost is Apr 9. A late frost as far out as Apr 25 happens in about 1 year in 10, so tender plants such as tomatoes and peppers are safest after that cautious date.
When is the first frost in Harrisburg, PA?
The average first fall frost is Nov 2. It can arrive as early as Oct 18 in about 1 year in 10, so plan to harvest tender crops before then.
How long is the growing season in Harrisburg, PA?
The average freeze-free season is about 206 days, between the average last spring frost and the average first fall frost.
Where do these dates come from?
They come from the NOAA 1991 to 2020 U.S. Climate Normals for the Middletown Harrisburg International Airport, PA station. Hills, valleys, lakes and city heat can shift frost by a week or more, so compare with neighbors who garden near you.