When to plant in Adelphi, MD
USDA Zone 7bHere are the average frost dates, USDA hardiness zone, and a month-by-month planting calendar for Adelphi, Maryland — all computed from Adelphi's nearest NOAA weather station.
In zone 7b, Adelphi supports a wide range of perennials year-round; the frost dates above are what set your annual vegetable timing.
The average first fall frost in Adelphi is now 5 days later than in the 1981–2010 normals. See how frost dates are shifting nationwide →
Frost probability
BELTSVILLE · 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 Adelphi’s own odds, recorded at BELTSVILLE.
| Threshold | SPRING 10% | SPRING 50% | SPRING 90% | FALL 10% | FALL 50% | FALL 90% |
|---|---|---|---|---|---|---|
| 36°F | May 11 | Apr 24 | Apr 10 | Oct 7 | Oct 21 | Nov 2 |
| 32°F | May 1 | Apr 10 | Mar 27 | Oct 16 | Nov 1 | Nov 14 |
| 28°F | Apr 10 | Mar 29 | Mar 12 | Oct 29 | Nov 11 | Nov 30 |
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 Adelphi, drawn to the day from the local frost dates. The dashed line is today.
Nearby weather stations
3 within 11 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.
Adelphi planting FAQ
When is the last spring frost in Adelphi, MD?
On average, the last spring frost in Adelphi is around April 10 (50% probability at 32°F, from 1991–2020 NOAA normals). Wait until after this date to set out tender plants like tomatoes and peppers.
When is the first fall frost in Adelphi, MD?
The first fall frost in Adelphi typically arrives around November 1 (50% probability at 32°F). Harvest or protect frost-sensitive crops before then.
What hardiness zone is Adelphi in?
Adelphi is in USDA hardiness zone 7b. In zone 7b, winters are moderate — most common vegetables grow well in season.
How long is the growing season in Adelphi?
Adelphi has about 205 frost-free days — a moderate growing season — between the average last spring frost (April 10) and first fall frost (November 1).
When should I plant tomatoes in Adelphi?
For Adelphi, sow tomatoes indoors about February 13–February 27 and move the seedlings out around April 17, after the last spring frost.
Never miss a window in Adelphi
An email when it’s time to start seeds, transplant, and sow — timed to Adelphi’s frost dates. Double opt-in, one-click unsubscribe, no spam.
Nearby cities
8 within reach- Langley Park · 1 km
- College Park · 3 km
- Chillum · 4 km
- Takoma Park · 4 km
- Hyattsville · 4 km
- Silver Spring · 5 km
- White Oak · 6 km
- Beltsville · 6 km
Frost dates recorded at BELTSVILLE, 5 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 Adelphi, MD — Frost Dates & Zone 7b." Frost normals: NOAA NCEI U.S. Climate Normals 1991–2020, station USC00180700. Retrieved from https://blissgarden.com/maryland/adelphi.