Grassflat, PA frost dates
Last spring frostMay 21median date
First fall frostSep 27median date
Growing season129 daysfrost-free
Hardiness zone6aZone 6a
How Grassflat compares
- In 8 years out of 10, the last spring frost in Grassflat falls between April 30 and June 1, a 32-day window. The first fall frost falls between September 12 and October 13.
- The median last frost is 24 days later than the Pennsylvania median of Apr 27.
- Its 129-day growing season is among the shortest of the 1,787 Pennsylvania places with a regular frost season.
- The last frost is 22 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 175 nights a year at or below 32°F.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | April 30 |
| 50% (median) | May 21 |
| 10% (safe for tender plants) | June 1 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | September 12 |
| 50% (median) | September 27 |
| 90% (late) | October 13 |
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 Grassflat, PA
Grassflat, PA frost dates — last frost May 21, first frost Sep 27, zone 6a. whenisthelastfrost.com
Crop
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Start indoors: Feb 26 to Mar 12Transplant outside: Apr 23 to May 7
Start indoors: Mar 12 to Mar 26Transplant outside: Jun 4 to Jun 18
Start indoors: Mar 12 to Mar 26Transplant outside: Jun 4 to Jun 18
Start indoors: Mar 26 to Apr 9Transplant outside: May 28 to Jun 11
Start indoors: Mar 26 to Apr 9Transplant outside: Apr 30 to May 14Sow outdoors: Apr 23 to May 28Plant for fall: Aug 2 to Aug 30
Start indoors: Mar 26 to Apr 9Transplant outside: Apr 23 to May 7Sow outdoors: Apr 23 to May 7Plant for fall: Jul 19 to Aug 9
Start indoors: Mar 26 to Apr 9Transplant outside: May 7 to May 21Plant for fall: Jun 21 to Jul 12
Start indoors: Mar 26 to Apr 9Transplant outside: Apr 30 to May 14Plant for fall: Jun 21 to Jul 12
Start indoors: Mar 26 to Apr 9Transplant outside: May 7 to May 21Plant for fall: Jun 21 to Jul 12
Start indoors: Apr 9 to Apr 23Transplant outside: Jun 11 to Jun 25Sow outdoors: Jun 11 to Jun 25
Start indoors: Apr 9 to Apr 23Transplant outside: May 28 to Jun 11
Sow outdoors: Apr 9 to Apr 30Plant for fall: Jul 5 to Jul 26
Sow outdoors: Apr 9 to Apr 30Plant for fall: Aug 2 to Aug 23
Sow outdoors: Apr 16 to May 28Plant for fall: Aug 16 to Sep 6
Start indoors: Apr 23 to Apr 30Transplant outside: Jun 4 to Jun 11Sow outdoors: May 28 to Jun 11Plant for fall: Jul 12 to Jul 26
Start indoors: Apr 23 to Apr 30Sow outdoors: May 28 to Jun 11Plant for fall: Jul 19 to Aug 2
Start indoors: Apr 23 to Apr 30Sow outdoors: May 28 to Jun 11
Start indoors: Apr 23 to Apr 30Transplant outside: Jun 4 to Jun 18
Sow outdoors: Apr 30 to May 28Plant for fall: Jul 5 to Jul 19
Sow outdoors: Apr 30 to May 28Plant for fall: Jul 19 to Aug 2
Sow outdoors: Apr 30 to May 21
Sow outdoors: May 7 to Jun 4Plant for fall: Jul 19 to Aug 2
Sow outdoors: May 7 to May 28Plant for fall: Aug 2 to Aug 23
Sow outdoors: May 28 to Jun 18Plant for fall: Jul 12 to Jul 26
Sow outdoors: May 28 to Jun 11
Transplant outside: Jun 4 to Jun 25
Plant for fall: Sep 13 to Oct 18
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in Grassflat, PA
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Feb 26 – Mar 12 | Apr 23 – May 7 | — | — |
| Peppers | Mar 12 – Mar 26 | Jun 4 – Jun 18 | — | — |
| Eggplant | Mar 12 – Mar 26 | Jun 4 – Jun 18 | — | — |
| Tomatoes | Mar 26 – Apr 9 | May 28 – Jun 11 | — | — |
| Lettuce | Mar 26 – Apr 9 | Apr 30 – May 14 | Apr 23 – May 28 | Aug 2 – Aug 30 |
| Kale | Mar 26 – Apr 9 | Apr 23 – May 7 | Apr 23 – May 7 | Jul 19 – Aug 9 |
| Broccoli | Mar 26 – Apr 9 | May 7 – May 21 | — | Jun 21 – Jul 12 |
| Cabbage | Mar 26 – Apr 9 | Apr 30 – May 14 | — | Jun 21 – Jul 12 |
| Cauliflower | Mar 26 – Apr 9 | May 7 – May 21 | — | Jun 21 – Jul 12 |
| Okra | Apr 9 – Apr 23 | Jun 11 – Jun 25 | Jun 11 – Jun 25 | — |
| Basil | Apr 9 – Apr 23 | May 28 – Jun 11 | — | — |
| Peas | — | — | Apr 9 – Apr 30 | Jul 5 – Jul 26 |
| Spinach | — | — | Apr 9 – Apr 30 | Aug 2 – Aug 23 |
| Radishes | — | — | Apr 16 – May 28 | Aug 16 – Sep 6 |
| Cucumbers | Apr 23 – Apr 30 | Jun 4 – Jun 11 | May 28 – Jun 11 | Jul 12 – Jul 26 |
| Zucchini & Summer Squash | Apr 23 – Apr 30 | — | May 28 – Jun 11 | Jul 19 – Aug 2 |
| Winter Squash & Pumpkins | Apr 23 – Apr 30 | — | May 28 – Jun 11 | — |
| Melons & Watermelon | Apr 23 – Apr 30 | Jun 4 – Jun 18 | — | — |
| Carrots | — | — | Apr 30 – May 28 | Jul 5 – Jul 19 |
| Beets | — | — | Apr 30 – May 28 | Jul 19 – Aug 2 |
| Potatoes | — | — | Apr 30 – May 21 | — |
| Swiss Chard | — | — | May 7 – Jun 4 | Jul 19 – Aug 2 |
| Cilantro | — | — | May 7 – May 28 | Aug 2 – Aug 23 |
| Green Beans | — | — | May 28 – Jun 18 | Jul 12 – Jul 26 |
| Sweet Corn | — | — | May 28 – Jun 11 | — |
| Sweet Potatoes | — | Jun 4 – Jun 25 | — | — |
| Garlic | — | — | — | Sep 13 – Oct 18 |
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 Clarence, PA weather station, 15 km away (elevation 1,391 ft (424 m)).
Frost dates near Grassflat
- Drifting May 21 · Sep 27
- Lanse May 13 · Oct 1
- Kylertown May 13 · Oct 1
- Winburne May 13 · Oct 1
- Munson May 13 · Oct 1
- Allport May 13 · Oct 1
- Moshannon May 21 · Sep 27
- Morrisdale May 13 · Oct 1
- Hawk Run May 13 · Oct 1
- Karthaus May 21 · Sep 27
Frequently asked questions
When is the last frost in Grassflat, PA?
The median last spring frost in Grassflat, PA is May 21. 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 Grassflat, PA?
The median first fall frost is September 27, with about a 10% chance of frost before September 12.
How long is the growing season in Grassflat, PA?
About 129 days between the median last spring frost and first fall frost.
What planting zone is Grassflat, PA?
Grassflat, PA is in USDA hardiness zone 6a.