Pennsylvania vegetable planting calendar 2027: frost dates and when to plant
In Pennsylvania, the average last spring frost is April 15 in Harrisburg and March 30 in Philadelphia (NOAA 1991-2020 normals). Below are planting dates for Harrisburg and Philadelphia for 27 common vegetables and herbs, worked out the way the Rowtime app does it: NOAA's average frost dates for the nearest weather station, with the planting rules of state extension guides. Dates are for the 2027 season.
Rowtime: Garden Planner works these dates out for your own ZIP code in Pennsylvania, shows where each one comes from, and recalculates when a planting slips. Get Rowtime on the App Store.
Dates are estimates. Check your local extension office before you plant, and use your own frost records if you have them. Dates shift by a week or more within a state, so pick the city closest to your conditions.
Harrisburg
When to plant tomatoes in Harrisburg?
In Harrisburg, Pennsylvania, the average last spring frost is April 15 and the average first fall frost is October 23 (NOAA 1991-2020 normals, HARRISBURG 1 NE station, 3.2 km from ZIP 17101). For tomatoes, start seeds indoors March 20 to May 26 and plant out seedlings May 2 to July 25, following University of Maryland Extension (Home & Garden Information Center) and Purdue University Extension. Dates are for the 2027 season; sources last checked October 24, 2026.
Frost dates for Harrisburg (17101)
- Last spring frost: Apr 15 on average, May 2 for a 10% risk of a later frost.
- First fall frost: Oct 23 on average, Oct 7 for a 10% risk of an earlier frost.
- USDA hardiness zone 7a (PRISM 2023 listing).
| Crop | When |
|---|---|
| Beet | Sow outdoors: Apr 4 to Apr 18 Sow outdoors for fall: Aug 12 to Sep 9 |
| Broccoli | Start seeds indoors: Feb 27 to Apr 5 Plant out seedlings: Mar 21 to Apr 4 Plant out seedlings for fall: Aug 12 to Sep 9 |
| Cabbage | Start seeds indoors: Feb 20 to Mar 19 Plant out seedlings: Mar 21 to Apr 4 Plant out seedlings for fall: Aug 12 to Sep 9 |
| Carrot | Sow outdoors: Apr 4 to Apr 18 |
| Cauliflower | Start seeds indoors: Mar 6 to Apr 5 Plant out seedlings: Apr 4 to Apr 18 Plant out seedlings for fall: Jun 23 to Jul 23 |
| Cucumber | Sow outdoors: May 16 to Aug 14 |
| Eggplant | Start seeds indoors: Apr 6 to May 5 Plant out seedlings: May 16 to Jul 25 |
| Green onion | Plant onion sets: Mar 21 to Apr 4 Plant out seedlings for fall: Aug 12 to Sep 9 |
| Kale | Sow outdoors: Mar 21 to Apr 4 Sow outdoors for fall: Aug 12 to Sep 9 |
| Lettuce | Sow outdoors: Apr 4 to Apr 18 Sow outdoors for fall: Aug 12 to Sep 9 |
| Melon and watermelon | Sow outdoors: May 16 to Jul 15 |
| Okra | Plant out seedlings: May 16 to Aug 19 |
| Onion | Plant onion sets: Mar 21 to Apr 4 |
| Pea | Sow outdoors: Mar 21 to Apr 4 |
| Pepper | Start seeds indoors: Mar 20 to Apr 19 Plant out seedlings: May 16 to Jul 25 |
| Potato | Plant seed potatoes: Mar 21 to Apr 4 |
| Snap bean | Sow outdoors: May 2 to Aug 24 |
| Spinach | Sow outdoors: Mar 21 to Apr 4 Sow outdoors for fall: Aug 12 to Sep 9 |
| Summer squash | Sow outdoors: May 16 to Aug 24 |
| Sweet corn | Sow outdoors: May 2 to Jul 25 |
| Sweet potato | Sprout slips indoors: Apr 20 to May 19 Plant out slips: May 16 to Jun 15 |
| Tomato | Start seeds indoors: Mar 20 to May 26 Plant out seedlings: May 2 to Jul 25 |
| Winter squash and pumpkin | Sow outdoors: May 16 to Jul 15 |
| Basil | Plant outdoors: May 19 to Aug 18 |
| Cilantro | Sow outdoors: Feb 19 to Apr 18 Sow outdoors for fall: Aug 31 to Sep 14 |
| Dill | Sow outdoors: Apr 3 to Apr 18 Sow outdoors for fall: Jul 16 to Aug 30 |
| Parsley | Sow outdoors: Apr 6 to May 5 Plant outdoors for fall: Jul 16 to Sep 14 |
Philadelphia
When to plant tomatoes in Philadelphia?
In Philadelphia, Pennsylvania, the average last spring frost is March 30 and the average first fall frost is November 17 (NOAA 1991-2020 normals, PHILA FRANKLIN INST station, 1.4 km from ZIP 19107). For tomatoes, start seeds indoors March 4 to May 10 and plant out seedlings April 12 to August 19, following University of Maryland Extension (Home & Garden Information Center) and Purdue University Extension. Dates are for the 2027 season; sources last checked October 24, 2026.
Frost dates for Philadelphia (19107)
- Last spring frost: Mar 30 on average, Apr 12 for a 10% risk of a later frost.
- First fall frost: Nov 17 on average, Nov 4 for a 10% risk of an earlier frost.
- USDA hardiness zone 7b (PRISM 2023 listing).
| Crop | When |
|---|---|
| Beet | Sow outdoors: Mar 15 to Mar 29 Sow outdoors for fall: Sep 9 to Oct 7 |
| Broccoli | Start seeds indoors: Feb 11 to Mar 20 Plant out seedlings: Mar 1 to Mar 15 Plant out seedlings for fall: Sep 9 to Oct 7 |
| Cabbage | Start seeds indoors: Feb 4 to Mar 3 Plant out seedlings: Mar 1 to Mar 15 Plant out seedlings for fall: Sep 9 to Oct 7 |
| Carrot | Sow outdoors: Mar 15 to Mar 29 |
| Cauliflower | Start seeds indoors: Feb 18 to Mar 20 Plant out seedlings: Mar 15 to Mar 29 Plant out seedlings for fall: Jul 18 to Aug 17 |
| Cucumber | Sow outdoors: Apr 26 to Sep 8 |
| Eggplant | Start seeds indoors: Mar 21 to Apr 19 Plant out seedlings: Apr 26 to Aug 19 |
| Green onion | Plant onion sets: Mar 1 to Mar 15 Plant out seedlings for fall: Sep 9 to Oct 7 |
| Kale | Sow outdoors: Mar 1 to Mar 15 Sow outdoors for fall: Sep 9 to Oct 7 |
| Lettuce | Sow outdoors: Mar 15 to Mar 29 Sow outdoors for fall: Sep 9 to Oct 7 |
| Melon and watermelon | Sow outdoors: Apr 26 to Aug 9 |
| Okra | Plant out seedlings: Apr 26 to Sep 13 |
| Onion | Plant onion sets: Mar 1 to Mar 15 |
| Pea | Sow outdoors: Mar 1 to Mar 15 |
| Pepper | Start seeds indoors: Mar 4 to Apr 3 Plant out seedlings: Apr 26 to Aug 19 |
| Potato | Plant seed potatoes: Mar 1 to Mar 15 |
| Snap bean | Sow outdoors: Apr 12 to Sep 18 |
| Spinach | Sow outdoors: Mar 1 to Mar 15 Sow outdoors for fall: Sep 9 to Oct 7 |
| Summer squash | Sow outdoors: Apr 26 to Sep 18 |
| Sweet corn | Sow outdoors: Apr 12 to Aug 19 |
| Sweet potato | Sprout slips indoors: Apr 4 to May 3 Plant out slips: Apr 26 to Jul 10 |
| Tomato | Start seeds indoors: Mar 4 to May 10 Plant out seedlings: Apr 12 to Aug 19 |
| Winter squash and pumpkin | Sow outdoors: Apr 26 to Aug 9 |
| Basil | Plant outdoors: May 3 to Aug 2 |
| Cilantro | Sow outdoors: Feb 3 to Apr 2 Sow outdoors for fall: Sep 25 to Oct 9 |
| Dill | Sow outdoors: Mar 18 to Apr 2 Sow outdoors for fall: Aug 10 to Sep 24 |
| Parsley | Sow outdoors: Mar 21 to Apr 19 Plant outdoors for fall: Aug 10 to Oct 9 |
Sources
Planting rules, in the order Rowtime tries them here:
- Purdue University Extension, Indiana Vegetable Planting Calendar (HO-186-W). Checked October 20, 2026.
- University of Maryland Extension (Home & Garden Information Center), Vegetable Planting Calendar for Central Maryland. Checked October 24, 2026.
- NC State Extension, Central North Carolina Planting Calendar for Annual Vegetables, Fruits, and Herbs (AG-756-01). Checked October 21, 2026.
Frost dates, locations and zones:
- NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020 annual/seasonal (freeze probabilities).
- U.S. Census Bureau, 2025 Gazetteer Files: ZIP Code Tabulation Areas.
- PRISM Group, Oregon State University / USDA ARS, 2023 USDA Plant Hardiness Zone Map ZIP code listings. PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed 20 Oct 2026.
How the dates are worked out: a guide's rule such as "two weeks after the last frost" is applied to the station's NOAA date. Purdue's dates are 10% dates, so they are counted from the station's 10% date. When a guide gives no last date, the window closes early enough for the crop's longest days to harvest before the first fall frost. When a guide gives no first date for a fall planting, no fall window is shown. "Season too short" means the guide's window would close before it opens at this station's frost dates.
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