Allentown, PA · zone 6b · ~186 frost-free days
When to plant in Allentown: frost dates and zone 6b.
In Allentown, the typical last spring frost lands around Apr 20 and the first fall frost around Oct 23, giving you about 186 frost-free days. Cool-season crops go out before the last frost; warm-season crops wait until after it.
The 2026 windows
Sow dates for Allentown, keyed to your frost.
| Crop | Start indoors | Spring sow / set out | Fall sow |
|---|---|---|---|
| Tomato, slicing | Mar 16 to May 16 | Apr 27 to Jun 27 | — |
| Lettuce, leaf | — | Mar 13 to Apr 27 | Aug 9 to Oct 8 |
| Carrot | — | Mar 13 to Apr 15 | Jul 28 to Aug 23 |
| Bush Bean | — | Apr 20 to Jun 10 | Jul 9 to Aug 11 |
| Cucumber, slicing | — | Apr 27 to Jul 27 | — |
| Pepper, bell | Mar 25 to May 16 | May 6 to Jun 27 | — |
| Kale | Jan 30 to Feb 27 | Mar 13 to Apr 10 | Jul 23 to Sep 7 |
| Spinach | — | Feb 27 to Apr 10 | Aug 9 to Sep 27 |
Allentown sits in Zone 6b, but two gardens in the same city can be a week or two apart. The planner works from your ZIP code's frost dates, not the zone, so the dates land right for your block, not the metro average.
Build your Allentown garden plan.
Tell the free planner what you want to eat and who you're feeding. It returns plant counts, spacing, and frost-safe sow dates for ZIP 18101 in about 60 seconds.
Allentown planting questions
What planting zone is Allentown, PA?+
Allentown is in USDA hardiness zone 6b. Growing zone, gardening zone, and planting zone all mean the same thing: the USDA number, 6b here. It tells you what survives winter, not when to plant. Frost dates set your planting time, and the free planner uses your exact ZIP code's frost dates, which can differ by weeks across one metro.
When is the last frost date in Allentown?+
The typical last spring frost in Allentown, PA is around Apr 20. That is an average from local history, not a guarantee, so tender crops like tomatoes and peppers are safer with a week of buffer after it.
When is the first frost date in Allentown?+
The typical first fall frost in Allentown, PA arrives around Oct 23, closing a growing season of roughly 186 frost-free days. Count backward from it to find the last date a fall crop can still finish.
What can I plant now in Allentown?+
It depends on the date. Cool-season crops like lettuce, kale, and spinach go out weeks before the last frost; warm-season crops like tomatoes and peppers wait until after Apr 20. The table above shows each crop's window; the free planner turns your ZIP into an exact, dated calendar.