When to Plant Onions in Pennsylvania
In Pennsylvania, the time to plant onions outside runs from Mar 2 – Mar 16 in Philadelphia to Apr 17 – May 1 in Hermitage. In Philadelphia, it's Mar 2 – Mar 16. The average last spring frost differs by about 7 weeks across the state (Mar 30 in Philadelphia, May 15 in Hermitage), so use the dates for the town nearest you.
Onions are cold-hardy. Plant sets or transplants early so they grow leaves before long summer days trigger bulbing.
- Start indoors: 10–12 weeks before the last frost.
- Plant outside: 2–4 weeks before the last frost.
Onions planting dates in Pennsylvania by city
| City | Zone | Start indoors | Plant outside |
|---|---|---|---|
| Allentown | 7a | Jan 26 – Feb 9 | Mar 23 – Apr 6 |
| Altoona | 6b | Jan 31 – Feb 14 | Mar 28 – Apr 11 |
| Baldwin | 6b | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Bethel Park | 6b | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Bethlehem | 7a | Jan 26 – Feb 9 | Mar 23 – Apr 6 |
| Carlisle | 7a | Jan 29 – Feb 12 | Mar 26 – Apr 9 |
| Chambersburg | 7a | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Chester | 7b | Jan 5 – Jan 19 | Mar 2 – Mar 16 |
| Easton | 7a | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Erie | 7a | Feb 1 – Feb 15 | Mar 29 – Apr 12 |
| Franklin Park | 6b | Jan 30 – Feb 13 | Mar 27 – Apr 10 |
| Greensburg | 6b | Feb 6 – Feb 20 | Apr 3 – Apr 17 |
| Hanover | 7a | Jan 30 – Feb 13 | Mar 27 – Apr 10 |
| Harrisburg | 7a | Jan 21 – Feb 4 | Mar 18 – Apr 1 |
| Hazleton | 6b | Feb 5 – Feb 19 | Apr 2 – Apr 16 |
| Hermitage | 6a | Feb 20 – Mar 6 | Apr 17 – May 1 |
| Indiana | 6b | Feb 13 – Feb 27 | Apr 10 – Apr 24 |
| Johnstown | 6b | Feb 4 – Feb 18 | Apr 1 – Apr 15 |
| Lancaster | 7a | Jan 25 – Feb 8 | Mar 22 – Apr 5 |
| Lansdale | 7a | Jan 17 – Jan 31 | Mar 14 – Mar 28 |
| Lebanon | 7a | Jan 26 – Feb 9 | Mar 23 – Apr 6 |
| McKeesport | 6b | Feb 7 – Feb 21 | Apr 4 – Apr 18 |
| Monroeville | 6b | Jan 28 – Feb 11 | Mar 25 – Apr 8 |
| Murrysville | 6b | Jan 28 – Feb 11 | Mar 25 – Apr 8 |
| New Castle | 6a | Feb 5 – Feb 19 | Apr 2 – Apr 16 |
| Norristown | 7a | Jan 14 – Jan 28 | Mar 11 – Mar 25 |
| Philadelphia | 7b | Jan 5 – Jan 19 | Mar 2 – Mar 16 |
| Phoenixville | 7a | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Pittsburgh | 6b | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Plum | 6b | Jan 22 – Feb 5 | Mar 19 – Apr 2 |
| Pottstown | 7a | Jan 26 – Feb 9 | Mar 23 – Apr 6 |
| Reading | 7a | Jan 20 – Feb 3 | Mar 17 – Mar 31 |
| Scranton | 6b | Jan 29 – Feb 12 | Mar 26 – Apr 9 |
| State College | 6b | Jan 26 – Feb 9 | Mar 23 – Apr 6 |
| West Chester | 7a | Feb 1 – Feb 15 | Mar 29 – Apr 12 |
| West Mifflin | 6b | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Whitehall | 6b | Jan 24 – Feb 7 | Mar 21 – Apr 4 |
| Wilkes-Barre | 7a | Jan 29 – Feb 12 | Mar 26 – Apr 9 |
| Williamsport | 6b | Jan 31 – Feb 14 | Mar 28 – Apr 11 |
| York | 7a | Feb 1 – Feb 15 | Mar 29 – Apr 12 |
Calculated from each town's average (50%) frost dates, from the nearest NOAA station (1991–2020). Typical dates for the 2027 planting season, based on NOAA's 1991–2020 averages. They are long-term odds, not a forecast: always check your local forecast before planting. Zones: 2023 USDA Plant Hardiness Zone Map (USDA-ARS and Oregon State University). Not the official map; see planthardiness.ars.usda.gov.
See all frost dates in Pennsylvania, or the general guide to when to plant onions.
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