When to plant in Horsham, PA
USDA Zone 7aEverything below — frost dates, hardiness zone, and what to plant when in Horsham, Pennsylvania — is derived from the closest NOAA station with complete climate normals.
In zone 7a, Horsham supports a wide range of perennials year-round; the frost dates above are what set your annual vegetable timing.
Frost probability
WILLOW GROVE NAS · 1991–2020The date the last spring and first fall frost occur, by threshold and probability. A 90% date is later in spring — and earlier in fall — than a 10% date; the 50% · 32°F row is what most gardeners plan around. These are Horsham’s own odds, recorded at WILLOW GROVE NAS.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 11 | Apr 24 | Apr 10 | Oct 6 | Oct 21 | Nov 4 |
| 32°F | Apr 27 | Apr 11 | Mar 29 | Oct 17 | Nov 1 | Nov 17 |
| 28°F | Apr 12 | Mar 30 | Mar 15 | Nov 1 | Nov 13 | Dec 1 |
Download this table as CSV ↓ — every threshold and probability, plus this city’s planting-window dates.
What to plant now
TODAY · JULY 19Full-year planting calendar
Each bar is the exact window to take a planting action in Horsham, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 16 km · complete 32°F normalsWhen stations disagree by more than a few days, that spread is real microclimate variation — elevation, water, urban heat. Judge which station best matches your own yard.
Horsham planting FAQ
When is the last spring frost in Horsham, PA?
Horsham's average last spring frost falls near April 11 — the 50% mark at 32°F in the 1991–2020 normals. Hold tender transplants until the risk has passed, then plant out.
When is the first fall frost in Horsham, PA?
Expect Horsham's first fall frost near November 1 — a 50% chance of 32°F by that date. Bring in or cover tender crops ahead of it.
What hardiness zone is Horsham in?
Horsham is in USDA hardiness zone 7a. In zone 7a, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Horsham?
Horsham has about 204 frost-free days — a moderate growing season — between the average last spring frost (April 11) and first fall frost (November 1).
When should I plant tomatoes in Horsham?
For Horsham, sow tomatoes indoors about February 14–February 28 and move the seedlings out around April 18, after the last spring frost.
Never miss a window in Horsham
An email when it’s time to start seeds, transplant, and sow — timed to Horsham’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Willow Grove · 4 km
- Roslyn · 6 km
- Montgomeryville · 11 km
- Lansdale · 14 km
- Norristown · 18 km
- Philadelphia · 19 km
- Bala Cynwyd · 20 km
- King of Prussia · 23 km
Frost dates recorded at WILLOW GROVE NAS, 2 km from the city center · 1991–2020 NOAA climate normals · zone from the USDA/PRISM 2023 map. How we compute this.
BlissGarden. "When to Plant in Horsham, PA — Frost Dates & Zone 7a." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USW00014793. Retrieved from https://blissgarden.com/pennsylvania/horsham.