USDA hardiness zone lookup
Allentown (18101) — USDA Zone 6b
Allentown, Pennsylvania · 173-day growing season
Frost dates and growing season for 18101
| USDA hardiness zone | Zone 6b |
|---|---|
| Average last spring frost | April 25 |
| Average first fall frost | October 15 |
| Growing season length | ~173 days |
| Temperature range (F) | -10 to 0°F |
| Temperature range (C) | -23 to -18°C |
These are 50%-probability averages modeled from this ZIP's USDA hardiness zone and regional climate normals — not a single-station reading. In a typical year the last spring frost will have passed by April 25, but in a colder-than-average year it can run 1-2 weeks later. Plant tender crops (tomatoes, peppers, basil) once both soil and night temperatures are consistently warm — a thermometer beats the calendar.
Growing season in Allentown
Allentown, Pennsylvania sits in USDA Zone 6b, with roughly 173 frost-free days between an average last spring frost around April 25 and a first fall frost around October 15. That is a standard temperate season — most common vegetables finish comfortably, and a single main planting plus one succession round works well.
What grows in Allentown
Allentown falls in USDA Zone 6b, which means the same hardiness constraints apply as the full Zone 6 guide. Vegetables, herbs, and fruit trees rated to Zone 6b (or hardier) will overwinter here in a typical year.
- Tomatoes (all types)
- Peppers, eggplant
- Squash, melons, cucumbers
- Beans, peas
- Sweet corn
- Apples, pears, peaches, plums
- Cherries, blueberries
- Asparagus, rhubarb
- Garlic (fall-planted)
- Strawberries
What to plant in Allentown this week
Allentown's last frost is around April 25. This is the spring transplant window — start tomatoes and peppers indoors if you haven't, and direct-sow cold-tolerant crops now.
- When to plant tomatoes in zone 6
- When to plant peppers in zone 6
- When to plant basil in zone 6
- When to plant bush beans in zone 6
- When to plant cucumbers in zone 6
Full planting calendar for Allentown
Crop-by-crop sowing, transplant, and harvest dates calibrated to zone 6 averages:
- When to plant tomatoes in zone 6
- When to plant peppers in zone 6
- When to plant basil in zone 6
- When to plant garlic in zone 6
- When to plant lettuce in zone 6
- When to plant bush beans in zone 6
- When to plant cucumbers in zone 6
- When to plant summer squash in zone 6
- When to plant peas in zone 6
- When to plant carrots in zone 6
Local microclimate notes
Zone tables give you the average — but Allentowngardens vary. South-facing walls and paved areas can run a full half-zone warmer than the published rating. Low-lying spots, frost pockets, and shaded north sides can run colder. If you've gardened here a few seasons, your own frost record (the last time you actually got frost damage) is more accurate than any national average.
Source and methodology
Hardiness zone from the USDA Plant Hardiness Zone Map (2023 revision). Frost-date and growing-season figures are modeled from this ZIP's USDA hardiness zone and regional NOAA 1991-2020 climate normals — they are zone-level estimates, not a per-station record, so treat them as planning guidance and confirm against your own local frost history. Crop recommendations are drawn from US Cooperative Extension references and curated by the Growli editorial team. Last reviewed May 2026.
Nearby ZIP codes in Pennsylvania
- 19102 — Philadelphia (Zone 7b)
- 19103 — Philadelphia (Center City) (Zone 7b)
- 15222 — Pittsburgh (Zone 6b)
- 17101 — Harrisburg (Zone 7a)
- 16501 — Erie (Zone 6b)
- 19104 — Philadelphia (University City) (Zone 7b)
- 19111 — Philadelphia (Fox Chase) (Zone 7a)
- 19120 — Philadelphia (Olney) (Zone 7b)
- 19124 — Philadelphia (Frankford) (Zone 7b)
- 19143 — Philadelphia (Southwest) (Zone 7b)
- 15213 — Pittsburgh (Oakland) (Zone 6b)
- 15206 — Pittsburgh (East Liberty) (Zone 6b)
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