Mercer, PA frost dates
Last spring frostMay 15median date
First fall frostOct 3median date
Growing season141 daysfrost-free
Hardiness zone6aZone 6a
How Mercer compares
- In 8 years out of 10, the last spring frost in Mercer falls between April 30 and June 1, a 32-day window. The first fall frost falls between September 19 and October 19.
- The median last frost is 18 days later than the Pennsylvania median of Apr 27.
- Its 141-day growing season is longer than 5% of the 1,787 Pennsylvania places with a regular frost season (state median 175 days).
- The last frost is 16 days later than the zone 6a median of Apr 29. Hardiness zones measure winter cold, not season length, so use these dates rather than a zone 6a chart.
- The weather station records an average of 159 nights a year at or below 32°F.
- Compared with Youngstown, OH, 41 km away, the last frost here is 7 days later than there and the growing season is 16 days shorter.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 30 |
| 50% (median) | May 15 |
| 10% (safe for tender plants) | June 1 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 19 |
| 50% (median) | October 3 |
| 90% (late) | October 19 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for Mercer, PA
Mercer, PA frost dates — last frost May 15, first frost Oct 3, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Feb 20 to Mar 6Transplant outside: Apr 17 to May 1
Start indoors: Mar 6 to Mar 20Transplant outside: May 29 to Jun 12
Start indoors: Mar 6 to Mar 20Transplant outside: May 29 to Jun 12
Start indoors: Mar 20 to Apr 3Transplant outside: May 22 to Jun 5
Start indoors: Mar 20 to Apr 3Transplant outside: Apr 24 to May 8Sow outdoors: Apr 17 to May 22Plant for fall: Aug 8 to Sep 5
Start indoors: Mar 20 to Apr 3Transplant outside: Apr 17 to May 1Sow outdoors: Apr 17 to May 1Plant for fall: Jul 25 to Aug 15
Start indoors: Mar 20 to Apr 3Transplant outside: May 1 to May 15Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 20 to Apr 3Transplant outside: Apr 24 to May 8Plant for fall: Jun 27 to Jul 18
Start indoors: Mar 20 to Apr 3Transplant outside: May 1 to May 15Plant for fall: Jun 27 to Jul 18
Start indoors: Apr 3 to Apr 17Transplant outside: Jun 5 to Jun 19Sow outdoors: Jun 5 to Jun 19
Start indoors: Apr 3 to Apr 17Transplant outside: May 22 to Jun 5
Sow outdoors: Apr 3 to Apr 24Plant for fall: Jul 11 to Aug 1
Sow outdoors: Apr 3 to Apr 24Plant for fall: Aug 8 to Aug 29
Sow outdoors: Apr 10 to May 22Plant for fall: Aug 22 to Sep 12
Start indoors: Apr 17 to Apr 24Transplant outside: May 29 to Jun 5Sow outdoors: May 22 to Jun 5Plant for fall: Jul 18 to Aug 1
Start indoors: Apr 17 to Apr 24Sow outdoors: May 22 to Jun 5Plant for fall: Jul 25 to Aug 8
Start indoors: Apr 17 to Apr 24Sow outdoors: May 22 to Jun 5
Start indoors: Apr 17 to Apr 24Transplant outside: May 29 to Jun 12
Sow outdoors: Apr 24 to May 22Plant for fall: Jul 11 to Jul 25
Sow outdoors: Apr 24 to May 22Plant for fall: Jul 25 to Aug 8
Sow outdoors: Apr 24 to May 15
Sow outdoors: May 1 to May 29Plant for fall: Jul 25 to Aug 8
Sow outdoors: May 1 to May 22Plant for fall: Aug 8 to Aug 29
Sow outdoors: May 22 to Jun 12Plant for fall: Jul 18 to Aug 1
Sow outdoors: May 22 to Jun 5
Transplant outside: May 29 to Jun 19
Plant for fall: Sep 19 to Oct 24
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Mercer, PA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 20 – Mar 6 | Apr 17 – May 1 | — | — |
| Peppers | Mar 6 – Mar 20 | May 29 – Jun 12 | — | — |
| Eggplant | Mar 6 – Mar 20 | May 29 – Jun 12 | — | — |
| Tomatoes | Mar 20 – Apr 3 | May 22 – Jun 5 | — | — |
| Lettuce | Mar 20 – Apr 3 | Apr 24 – May 8 | Apr 17 – May 22 | Aug 8 – Sep 5 |
| Kale | Mar 20 – Apr 3 | Apr 17 – May 1 | Apr 17 – May 1 | Jul 25 – Aug 15 |
| Broccoli | Mar 20 – Apr 3 | May 1 – May 15 | — | Jun 27 – Jul 18 |
| Cabbage | Mar 20 – Apr 3 | Apr 24 – May 8 | — | Jun 27 – Jul 18 |
| Cauliflower | Mar 20 – Apr 3 | May 1 – May 15 | — | Jun 27 – Jul 18 |
| Okra | Apr 3 – Apr 17 | Jun 5 – Jun 19 | Jun 5 – Jun 19 | — |
| Basil | Apr 3 – Apr 17 | May 22 – Jun 5 | — | — |
| Peas | — | — | Apr 3 – Apr 24 | Jul 11 – Aug 1 |
| Spinach | — | — | Apr 3 – Apr 24 | Aug 8 – Aug 29 |
| Radishes | — | — | Apr 10 – May 22 | Aug 22 – Sep 12 |
| Cucumbers | Apr 17 – Apr 24 | May 29 – Jun 5 | May 22 – Jun 5 | Jul 18 – Aug 1 |
| Zucchini & Summer Squash | Apr 17 – Apr 24 | — | May 22 – Jun 5 | Jul 25 – Aug 8 |
| Winter Squash & Pumpkins | Apr 17 – Apr 24 | — | May 22 – Jun 5 | — |
| Melons & Watermelon | Apr 17 – Apr 24 | May 29 – Jun 12 | — | — |
| Carrots | — | — | Apr 24 – May 22 | Jul 11 – Jul 25 |
| Beets | — | — | Apr 24 – May 22 | Jul 25 – Aug 8 |
| Potatoes | — | — | Apr 24 – May 15 | — |
| Swiss Chard | — | — | May 1 – May 29 | Jul 25 – Aug 8 |
| Cilantro | — | — | May 1 – May 22 | Aug 8 – Aug 29 |
| Green Beans | — | — | May 22 – Jun 12 | Jul 18 – Aug 1 |
| Sweet Corn | — | — | May 22 – Jun 5 | — |
| Sweet Potatoes | — | May 29 – Jun 19 | — | — |
| Garlic | — | — | — | Sep 19 – Oct 24 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the Mercer, PA weather station, about 1 km away (elevation 1,220 ft (372 m)).
Frost dates near Mercer
- Fredonia May 15 · Oct 3
- Jackson Center May 15 · Oct 3
- New Wilmington Apr 30 · Oct 23
- Grove City May 7 · Oct 14
- Volant Apr 30 · Oct 23
- Stoneboro May 15 · Oct 3
- Clark May 15 · Oct 3
- Clarks Mills May 15 · Oct 3
- Hermitage May 15 · Oct 3
- Transfer May 15 · Oct 3
Frequently asked questions
When is the last frost in Mercer, PA?
The median last spring frost in Mercer, PA is May 15. There is still about a 10% chance of frost after June 1, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in Mercer, PA?
The median first fall frost is October 3, with about a 10% chance of frost before September 19.
How long is the growing season in Mercer, PA?
About 141 days between the median last spring frost and first fall frost.
What planting zone is Mercer, PA?
Mercer, PA is in USDA hardiness zone 6a.