Horsham, PA planting zone & frost dates
Horsham is in USDA hardiness zone 7a. The last spring frost usually comes around April 11 and the first fall frost around November 1, for a growing season of about 205 days.
Planting calendar for Horsham
Dates are counted from the average last spring frost (April 11) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: Apr 18 – Apr 25 |
| Peppers | Start seeds indoors: Jan 31 – Feb 14 Transplant outdoors: Apr 25 – May 2 |
| Eggplant | Start seeds indoors: Jan 31 – Feb 14 Transplant outdoors: Apr 25 – May 2 |
| Broccoli | Start seeds indoors: Jan 31 – Feb 14 Transplant outdoors: Mar 14 – Mar 28 |
| Cabbage | Start seeds indoors: Jan 31 – Feb 14 Transplant outdoors: Mar 14 – Mar 28 |
| Onions (sets) | Plant outdoors: Mar 14 – Mar 28 |
| Peas | Sow outdoors: Feb 28 – Mar 14 |
| Spinach | Sow outdoors: Feb 28 – Mar 14 |
| Lettuce | Sow outdoors: Mar 14 – Mar 28 |
| Carrots | Sow outdoors: Mar 14 – Mar 28 |
| Potatoes | Plant outdoors: Mar 14 – Mar 28 |
| Beans | Sow outdoors: Apr 18 – Apr 25 |
| Sweet corn | Sow outdoors: Apr 18 – Apr 25 |
| Cucumbers | Sow outdoors: Apr 18 – Apr 25 |
| Squash & zucchini | Sow outdoors: Apr 18 – Apr 25 |
| Basil | Start seeds indoors: Feb 28 – Mar 14 Transplant outdoors: Apr 18 – Apr 25 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 6 (8 weeks before the average first fall frost on Nov 1).
Useful for zone 7a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Mar 29 | Apr 11 | Apr 27 |
| First 32°F frost in fall is before | Nov 17 | Nov 1 | Oct 17 |
How to read it: in spring there is a 10% chance of a frost after April 27, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 17. A hard freeze (28°F) usually ends around March 30.
Hardiness zone by ZIP code in Horsham
- 19044 zone 7a
Nearby cities
- Willow Grove zone 7b, last frost Apr 11
- Abington zone 7b, last frost Apr 11
- Montgomeryville zone 7a, last frost Apr 11
- Lansdale zone 7a, last frost Apr 24
- Bensalem zone 7b, last frost Apr 21
- East Norriton zone 7a, last frost Apr 8
- Norristown zone 7a, last frost Apr 8
- Philadelphia zone 7b, last frost Mar 30
Questions
What growing zone is Horsham, PA?
Horsham is in USDA Plant Hardiness Zone 7a (average extreme winter low 0°F to 5°F), according to the USDA 2023 map.
When is the last frost in Horsham?
The average last spring frost (32°F) in Horsham is April 11. There is still a 10% chance of frost until April 27.
When can I plant tomatoes in Horsham?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 18 – Apr 25. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Willow Grove Nas, PA (USW00014793), 3.0 km (1.9 mi) from the city center, elevation 110 m, based on 15 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.