USDA zones 7a, 7b, 8a in District of Columbia
USDA plant hardiness zones 7a, 7b, 8a cover 7 locations across District of Columbia (average annual extreme minimum 0 to 15 °F): Washington, DC, Washington, DC, Washington, DC, Washington, DC, Washington, DC, Washington, DC, and 1 more. Average last spring frost across this state ranges March 24 (Washington) to April 9 (Washington), and growing seasons run 202–241 days (Washington to Washington) — even within one state, because hardiness sets winter survival, not planting dates. Here all 3 of its hardiness zones share this page rather than sit on 3 thin ones. The table below gives every District of Columbia location's own frost dates; the printable planting calendar uses Washington, this state's median-season location.
- USDA zones
- 7a, 7b, 8a0 to 15 °F
- Last frost range
- Mar 24–Apr 9avg, 32°F
- First frost range
- Oct 31–Nov 18avg, 32°F
- Growing season range
- 202–241days
Locations in this group
Every location below keeps its own USDA zone, weather station, and frost dates — they are listed together here, not averaged. Find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Zone | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|---|
| Washington | 8a | — | Natl Arboretum Dc | Mar 29 | Nov 8 | 224 |
| Washington | 8a | — | Dalecarlia Rsvr | Apr 9 | Oct 31 | 202 |
| Washington | 8a | Arlington, Alexandria, Fort Hunt, Belle Haven, Forest Heights | Washington Reagan Ap | Mar 24 | Nov 18 | 241 |
| Washington | 7b | Arlington, Potomac, McLean, Bethesda, North Bethesda, Annandale, +11 more | Dalecarlia Rsvr | Apr 9 | Oct 31 | 202 |
| Washington * | 7b | Andrews AFB, Suitland, Landover, Forestville, Chillum, Walker Mill, +5 more | Natl Arboretum Dc | Mar 29 | Nov 8 | 224 |
| Washington | 7b | Waldorf, Accokeek, Arlington, Clinton, Alexandria, Fort Washington, +12 more | Washington Reagan Ap | Mar 24 | Nov 18 | 241 |
| Washington | 7a | — | Natl Arboretum Dc | Mar 29 | Nov 8 | 224 |
* Washington is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Washington, representative)
Computed from Washington's average frost dates — the median-season location in this District of Columbiazones 7a, 7b, 8a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Feb 1 – Feb 15 | Apr 5 – Apr 12 | Jun 4 – Jun 24 | — | matures comfortably |
| Pepper | Very tender | Jan 18 – Feb 1 | Apr 12 – Apr 19 | Jun 11 – Jul 11 | — | matures comfortably |
| Cucumber | Tender | Mar 1 – Mar 8 | Apr 5 – Apr 12 | May 25 – Jun 14 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Apr 5 – Apr 12 | May 20 – Jun 4 | — | matures comfortably |
| Bush bean | Tender | — | Apr 5 – Apr 12 | May 25 – Jun 4 | Sep 9 – Sep 19 | matures comfortably |
| Sweet corn | Tender | — | Mar 29 – Apr 12 | May 28 – Jun 27 | — | matures comfortably |
| Basil | Very tender | Feb 15 – Mar 1 | Apr 5 – Apr 12 | May 5 – May 20 | — | matures comfortably |
| Lettuce | Half-hardy | Feb 15 – Mar 1 | Mar 1 – Mar 15 | Apr 15 – Apr 30 | Aug 26 – Sep 10 | matures comfortably |
| Pea | Hardy | — | Feb 15 – Mar 1 | Apr 11 – Apr 26 | Aug 16 – Aug 31 | matures comfortably |
| Spinach | Hardy | — | Feb 15 – Mar 1 | Mar 27 – Apr 6 | Sep 5 – Sep 15 | matures comfortably |
| Carrot | Half-hardy | — | Mar 8 – Mar 15 | May 7 – May 27 | Aug 6 – Aug 26 | matures comfortably |
| Broccoli | Half-hardy | Feb 1 – Feb 15 | Mar 1 – Mar 15 | Apr 25 – May 15 | Aug 11 – Aug 31 | matures comfortably |
Which crops fit this growing season
Using Washington's own 224-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Washington)
From NOAA's 1991–2020 Climate Normals at station USC00186350. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Apr 10 | Apr 28 | Oct 29 | Nov 10 | 200 |
| 32°F (freeze) | Mar 29 | Apr 11 | Nov 8 | Nov 23 | 224 |
| 28°F | Mar 17 | Mar 31 | Nov 20 | Dec 7 | 248 |
| 24°F | Mar 7 | Mar 22 | Dec 6 | Dec 28 | 274 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 7 locations is 4,518; Washington's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 4,518 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 7,183 | cool-season crops (brassicas, greens) |
Hardiness zones 7a, 7b, 8a in District of Columbia
District of Columbia's 3 hardiness zones (7a, 7b, 8a) — an average annual extreme minimum winter temperature range of 0 to 15 °F on the USDA's 2023 map — share this page District of Columbia is small enough that every one of its hardiness zones (7a, 7b, 8a) is combined onto this one page rather than split thin across several. Each location's own zone is in the table above. Hardiness sets winter survival, not planting dates; the frost calendar uses Washington, this page's representative location.
See all USDA hardiness zones across the site, or browse all District of Columbia locations.
Frequently asked questions
- What USDA hardiness zones does District of Columbia have?
- District of Columbia spans zones 7a, 7b, 8a — an average annual extreme minimum winter temperature range of 0 to 15 °F on the USDA's 2023 map — across 7 locations, each listed with its own zone in the table above. The zone does not set planting dates; see the frost calendar for that.
- Where in District of Columbia is the growing season longest?
- Washington runs the longest season on this page at about 241 days; Washington is shortest at about 202 days — hardiness zone is not what separates them, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in District of Columbia?
- Using Washington's frost dates (this page's median-season location): start seeds indoors about Feb 1 – Feb 15, then transplant outside about Apr 5 – Apr 12. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in District of Columbia have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 7 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.