Seasonal Planting in the United States¶
What Are Planting Zones?¶
The USDA Plant Hardiness Zone Map divides the United States into 13 zones (1–13), each split into "a" and "b" half-zones, based on the average annual extreme minimum winter temperature. The current edition (2023) reflects 30-year climate averages from 1991–2020 and shows that roughly half of the country has warmed by one half-zone since the 2012 edition — meaning longer growing seasons and shifted frost dates across most regions.
Zones are the baseline language for plant labels, seed catalogs, and extension service guidance throughout North America.
Zone Reference Table¶
| Zone | Min. Winter Temp (°F) | Broad Region | Examples |
|---|---|---|---|
| 3a | −40 to −35 | Northern Plains, northern MN | International Falls MN |
| 3b | −35 to −30 | Northern MN, upper WI | Duluth MN |
| 4a | −30 to −25 | Great Lakes, northern NE | Burlington VT |
| 4b | −25 to −20 | Northern Midwest | Minneapolis MN |
| 5a | −20 to −15 | Upper Midwest, New England | Chicago IL, Boston MA |
| 5b | −15 to −10 | Mid-Atlantic inland, Midwest | Columbus OH |
| 6a | −10 to −5 | Pacific NW, Mid-Atlantic | Portland OR, Philadelphia PA |
| 6b | −5 to 0 | Central Plains, Carolinas | Kansas City MO, Charlotte NC |
| 7a | 0 to 5 | Pacific NW lowlands, VA/TN | Seattle WA, Nashville TN |
| 7b | 5 to 10 | Pacific Coast, Oklahoma | Oklahoma City OK |
| 8a | 10 to 15 | Pacific Coast, Deep South | Dallas TX, Savannah GA |
| 8b | 15 to 20 | Gulf Coast, Puget Sound | Houston TX, Tacoma WA |
| 9a | 20 to 25 | Central CA, Gulf Coast | Sacramento CA, Tampa FL |
| 9b | 25 to 30 | Coastal CA, south TX | San Diego CA, McAllen TX |
| 10a | 30 to 35 | South Florida, Hawaii | Miami FL, Honolulu HI |
| 10b | 35 to 40 | Hawaii, far south FL | Key West FL |
| 11a+ | 40+ | Tropical Hawaii | Hilo HI |
Source: 2023 USDA Plant Hardiness Zone Map (planthardiness.ars.usda.gov). Public domain — not copyrighted.
Frost Date Overview by Region¶
Frost dates — last spring frost and first fall frost — define the bookends of the outdoor growing season. These are averages and can vary year to year by 2–4 weeks.
| Region | Last Spring Frost (avg.) | First Fall Frost (avg.) | Season Length |
|---|---|---|---|
| Northern Plains / Zone 3 | May 20 – June 1 | Sept 1 – 15 | 90–120 days |
| Upper Midwest / Zone 4–5 | May 1 – 15 | Sept 20 – Oct 1 | 130–150 days |
| Mid-Atlantic / Zone 6 | Apr 15 – May 1 | Oct 10 – Nov 1 | 165–200 days |
| Southeast / Zone 7–8 | Mar 1 – Apr 1 | Nov 1 – Dec 1 | 210–250 days |
| Gulf Coast / Zone 9 | Feb 1 – Mar 1 | Dec 1 – Jan 1 | 280–310 days |
| South Florida / Zone 10–11 | No reliable frost | No reliable frost | Year-round |
| Pacific Northwest (lowlands) / Zone 7–8 | Mar 15 – Apr 15 | Nov 1 – Dec 1 | 200–240 days |
| California Coast / Zone 9–10 | Feb 1 – Mar 1 | Dec 1 – Jan 15 | Year-round possible |
Seasonal Planting Calendar by Zone Group¶
Zones 3–4 (Northern/Alpine)¶
States: Northern MN, ND, SD highlands, WI northwoods, ME, northern MT, upper MI
| Season | What to Do |
|---|---|
| Late Winter (Feb–Mar) | Start onions, leeks, celery indoors (10–12 weeks before last frost) |
| Early Spring (Apr) | Start tomatoes, peppers, eggplant indoors. Direct sow peas outdoors under row cover. |
| Late Spring (May–June) | After last frost (late May/early June): transplant tomatoes, peppers, squash; direct sow beans, carrots, beets, cucumbers. |
| Summer (June–Aug) | Succession plant lettuce, radishes. Harvest early crops. Sow fall turnips and kale in early August. |
| Fall (Sept) | Harvest before first frost. Row-cover extension for hardy greens. |
| Key crops: | Cold-hardy vegetables (kale, carrots, beets, cabbage, potatoes), short-season tomato varieties |
Zones 5–6 (Upper Midwest, New England, Mid-Atlantic)¶
States: IL, IN, OH, PA, NY, NJ, DE, MD, VA (inland), WV, CO (Front Range), OR/WA (inland)
| Season | What to Do |
|---|---|
| Late Winter (Feb–Mar) | Start onions, leeks, peppers, eggplant indoors (10–12 weeks). |
| Early Spring (Mar–Apr) | Direct sow spinach, peas, carrots, radishes. Plant potatoes. Start tomatoes indoors. |
| Mid-Spring (Apr–May) | Transplant brassica starts (broccoli, cauliflower, cabbage). Harden off tomatoes/peppers. |
| Late Spring (May) | After last frost: transplant tomatoes, peppers, cucumbers, squash. Direct sow beans. |
| Summer (June–Aug) | Succession sow lettuce, beans, beets. Harvest garlic mid-July. Start fall brassicas in July. |
| Early Fall (Sept–Oct) | Direct sow spinach, kale, arugula for cold-season harvest. Garlic planting in Oct. |
| Key crops: | Tomatoes, peppers, cucumbers, squash, beans, brassicas, root vegetables, sweet corn |
Zones 7–8 (Pacific Northwest, Upper South, Mid-South)¶
States: WA (lowlands), OR (coast/valley), NC, VA (coast), TN, AR, KY, GA (north), SC, NM, TX (north)
| Season | What to Do |
|---|---|
| Winter (Jan–Feb) | In mild microclimates: grow overwintered spinach, kale, chard. Start onions, peppers, tomatoes indoors in Feb. |
| Early Spring (Mar) | Direct sow peas, carrots, beets, spinach, turnips. Transplant broccoli and cabbage. |
| Spring (Apr–May) | After last frost (mid-Mar to mid-Apr): transplant tomatoes, peppers, eggplant, basil. Plant sweet potatoes. |
| Summer (June–Aug) | Heat-tolerant crops: okra, southern peas, sweet corn. Succession plant beans. Start fall crops (broccoli, cabbage) in July. |
| Fall (Sept–Nov) | Plant garlic Oct–Nov. Direct sow greens, spinach, root vegetables for winter harvest. |
| Key crops: | Tomatoes, peppers, sweet potatoes, okra, greens year-round (PNW), brassicas |
Zones 9–10 (Gulf Coast, Central/Southern California, South Florida)¶
States: CA (Central Valley, coast), FL (south), TX (south), LA, MS (coast), AZ (lower), HI
| Season | What to Do |
|---|---|
| Winter (Dec–Feb) | Peak cool-season: plant tomatoes, peppers, beans (FL/TX/AZ). Greens, broccoli, cauliflower, root veg in full swing. |
| Early Spring (Feb–Mar) | Last push of cool-season crops before heat. Start heat-season starts (tomatoes, peppers). |
| Spring (Mar–Apr) | Transition to heat season: plant squash, cucumbers, beans, corn, okra, sweet potatoes. |
| Summer (June–Sept) | In FL/Gulf Coast: heat stress. Focus on heat-lovers (okra, sweet potato, southern peas). Many take a break in Aug. |
| Fall (Oct–Nov) | Start cool-season crops: tomatoes, peppers (second season in FL/TX). Greens, brassicas, root vegetables through winter. |
| Key crops: | Two main seasons (warm + cool). Citrus, avocado, mango (Zone 10+), tomatoes (spring and fall), okra, sweet potato |
Zones 10b–11 (Tropical Hawaii, Extreme South Florida)¶
States: Hawaii (most islands), Key West FL area
| Season | What to Do |
|---|---|
| Year-round | Continuous production possible. Rotate based on rainfall patterns rather than temperature. |
| Dry Season (May–Oct) | Focus on heat and drought-tolerant crops; irrigation management. |
| Wet Season (Nov–Apr) | Higher humidity; watch for fungal disease. Best season for many vegetables. |
| Key crops: | Taro, breadfruit, sweet potato, tropical fruits, papaya, banana, ginger, turmeric, beans |
How to Use This Reference¶
- Find your zone — enter your ZIP code at planthardiness.ars.usda.gov or use your local extension service.
- Identify your last spring frost date — check the Old Farmer's Almanac frost tool or your state's extension service.
- Count back from last frost — seed packets list "start indoors X weeks before last frost" or "direct sow after last frost."
- Account for microclimates — urban heat islands, south-facing slopes, proximity to large bodies of water, and elevation all shift your effective zone by 0.5–1 full zone.
- Watch the 2023 shifts — if you're on a zone boundary, check whether your area moved half a zone warmer since 2012 (the NPR interactive map is the best tool for this).
Key Resources¶
| Resource | URL | What It's For |
|---|---|---|
| USDA Interactive Map | planthardiness.ars.usda.gov | Official zone lookup by ZIP code |
| USDA Map Downloads | planthardiness.ars.usda.gov/pages/map-downloads | High-res national/state/regional PNG maps |
| NPR Zone Shift Map | apps.npr.org/plant-hardiness-garden-map | 2023 vs. 2012 change visualization |
| PlantMaps (by state) | plantmaps.com/climate-maps-and-data/hardiness-zones | State-by-state interactive maps |
| Gardenia.net Zone Chart | gardenia.net/guide/usda-planting-zones-complete-growing-zones-for-the-us | Zone-to-plant pairing guide |
Observatory Almanac reference document. Licensed MIT. Hardiness zone data derived from the 2023 USDA Plant Hardiness Zone Map (public domain).