Potomac, MD planting zone & frost dates
Potomac is in USDA hardiness zone 7b. The last spring frost usually comes around April 1 and the first fall frost around November 6, for a growing season of about 219 days.
Planting calendar for Potomac
Dates are counted from the average last spring frost (April 1) 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 4 – Feb 18 Transplant outdoors: Apr 8 – Apr 15 |
| Peppers | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Apr 15 – Apr 22 |
| Eggplant | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Apr 15 – Apr 22 |
| Broccoli | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Mar 4 – Mar 18 |
| Cabbage | Start seeds indoors: Jan 21 – Feb 4 Transplant outdoors: Mar 4 – Mar 18 |
| Onions (sets) | Plant outdoors: Mar 4 – Mar 18 |
| Peas | Sow outdoors: Feb 18 – Mar 4 |
| Spinach | Sow outdoors: Feb 18 – Mar 4 |
| Lettuce | Sow outdoors: Mar 4 – Mar 18 |
| Carrots | Sow outdoors: Mar 4 – Mar 18 |
| Potatoes | Plant outdoors: Mar 4 – Mar 18 |
| Beans | Sow outdoors: Apr 8 – Apr 15 |
| Sweet corn | Sow outdoors: Apr 8 – Apr 15 |
| Cucumbers | Sow outdoors: Apr 8 – Apr 15 |
| Squash & zucchini | Sow outdoors: Apr 8 – Apr 15 |
| Basil | Start seeds indoors: Feb 18 – Mar 4 Transplant outdoors: Apr 8 – Apr 15 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Sep 11 (8 weeks before the average first fall frost on Nov 6).
Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Mar 19 | Apr 1 | Apr 15 |
| First 32°F frost in fall is before | Nov 21 | Nov 6 | Oct 24 |
How to read it: in spring there is a 10% chance of a frost after April 15, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 24. A hard freeze (28°F) usually ends around March 22.
Hardiness zone by ZIP code in Potomac
- 20854 zone 7b
- 20859 zone 7b
Nearby cities
- Travilah zone 7b, last frost Apr 1
- North Potomac zone 7b, last frost Apr 1
- Rockville zone 7b, last frost Apr 1
- North Bethesda zone 7b, last frost Apr 1
- Bethesda zone 7b, last frost Apr 9
- Gaithersburg zone 7b, last frost Apr 1
- Aspen Hill zone 7b, last frost Apr 1
- Wheaton zone 7b, last frost Apr 1
Questions
What growing zone is Potomac, MD?
Potomac is in USDA Plant Hardiness Zone 7b (average extreme winter low 5°F to 10°F), according to the USDA 2023 map.
When is the last frost in Potomac?
The average last spring frost (32°F) in Potomac is April 1. There is still a 10% chance of frost until April 15.
When can I plant tomatoes in Potomac?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around Apr 8 – Apr 15. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Rockville 1 Ne, MD (USC00187705), 10.5 km (6.5 mi) from the city center, elevation 134 m, based on 14 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.