Zone 1 Planting Guide: When to Plant Vegetables in USDA Zone 1
Quick answer
In zone 1, the typical last spring frost is about May 29 and the first fall frost about Aug 27 (NOAA 1991–2020 medians across zone 1 ZIP codes). Transplant tomatoes around Jun 5, 1–2 weeks after the last frost, and start the seeds indoors Apr 3 – Apr 17. Look up your ZIP for local dates, since zones measure winter lows, not frost dates.
USDA hardiness zone 1 (1a and 1b) covers places where the coldest winter night averages -60 to -50°F. This guide times seed-starting, transplanting, and fall planting for a typical zone 1 last frost of May 29 and first fall frost of Aug 27.
Where these dates come from: every date range is counted from the median (50% probability) 32°F last spring and first fall frost dates in NOAA’s 1991–2020 U.S. Climate Normals for the area shown. The rule under each date, such as “4–6 weeks before last frost,” shows how it was counted. These are averages: in about half of years a frost still comes after the spring date, and elevation, nearby water and microclimate can shift your yard by a week or more. For dates for your exact location, enter your ZIP code in the planner.
How we count planting dates: the weeks before or after frost for each crop come from university extension planting guides: UNH Extension, When to Plant Your Vegetable Garden; Rutgers FS787, Starting Vegetable Seeds Indoors; Virginia Tech 426-331, Home Garden Vegetable Planting Guide; University of Maryland Extension, Vegetable Planting Calendar; and University of Idaho CIS 1209 (marigolds and zinnias). Bulb windows approximate Rutgers’ rule to plant when soil falls below 60°F (FS1220), and garlic follows SDSU, Illinois and Virginia Tech. Temperature notes: UMD (potatoes), UMN (sweet corn), UC ANR (peppers, hardening off), UMN (eggplant), Colorado State (tomatoes) and SDSU (hardening off).
Zone 1 frost dates
| Earliest 10% of ZIPs | Typical (median) | Latest 10% of ZIPs | |
|---|---|---|---|
| Last spring frost (32°F) | May 18 | May 29 | Jun 3 |
| First fall frost (32°F) | Aug 23 | Aug 27 | Sep 8 |
Based on 8 ZIP codes in Alaska with NOAA frost data (16 zone-1 ZIP codes in all), so the earliest and latest 10% are rough.
Frost dates: medians of the nearest NOAA NCEI 1991–2020 Climate Normals station (32°F, 50% probability) for each ZIP code in zone 1 (8 ZIPs). Zones: USDA 2023 Plant Hardiness Zone Map ZIP data, PRISM Climate Group (Oregon State University); this is a summary, not the official USDA map. Your local dates can differ by weeks — use the ZIP planner or frost-date tables.
What to plant each month in zone 1
| Month | What to plant, with typical zone 1 dates |
|---|---|
| March | Start indoors Mar 20 – Apr 3: Broccoli, Cabbage, Kale |
| April | Start indoors Apr 3 – Apr 17: Tomatoes, Peppers, Eggplant Direct sow Apr 17 – May 1: Peas, Spinach Start indoors Apr 17 – May 1: Basil Direct sow Apr 24 – May 15: Radishes |
| May | Direct sow May 1 – May 15: Lettuce Plant sets/transplants May 1 – May 15: Onions (sets/transplants) Transplant May 1 – May 15: Broccoli, Cabbage, Kale Start indoors May 8 – May 29: Marigolds, Zinnias Plant seed potatoes May 15 – May 22: Potatoes Direct sow / transplant May 29 – Jun 12: Marigolds, Zinnias |
| June | Fall transplant Jun 4 – Jun 18: Broccoli, Cabbage Transplant Jun 5 – Jun 12: Tomatoes, Basil Direct sow Jun 5 – Jun 12: Beans (bush & pole), Sweet corn, Cucumbers, Squash Direct sow Jun 5 – Jun 19: Pumpkins Transplant Jun 12 – Jun 19: Peppers, Eggplant Fall sow Jun 18 – Jul 2: Kale |
| July | Fall sow Jul 2 – Jul 16: Lettuce Fall sow Jul 9 – Jul 30: Spinach Fall sow Jul 16 – Jul 30: Radishes Fall plant bulbs Jul 30 – Sep 10: Daffodils |
| August | Fall plant bulbs Aug 13 – Sep 24: Tulips Fall plant cloves Aug 13 – Sep 17: Garlic |
Zone 1 planting calendar (23 crops)
Each date range is counted from the typical zone 1 frost dates above (last frost May 29, first fall frost Aug 27); the rule under each date shows how. Rows run in calendar order. For dates for your ZIP code, use the planner.
| Plant | Task | Dates (and how they are counted) | Expected harvest (estimate) |
|---|---|---|---|
| Broccoli | Start indoors | Mar 20 – Apr 38–10 weeks before last frost (avg. May 29) | — |
| Cabbage | Start indoors | Mar 20 – Apr 38–10 weeks before last frost (avg. May 29) | — |
| Kale | Start indoors | Mar 20 – Apr 38–10 weeks before last frost (avg. May 29) | — |
| Tomatoes | Start indoors | Apr 3 – Apr 176–8 weeks before last frost (avg. May 29) | — |
| Peppers | Start indoors | Apr 3 – Apr 176–8 weeks before last frost (avg. May 29) | — |
| Eggplant | Start indoors | Apr 3 – Apr 176–8 weeks before last frost (avg. May 29) | — |
| Peas | Direct sow | Apr 17 – May 14–6 weeks before last frost (avg. May 29) | Jun 16 – Jul 2060–80 days from seeding |
| Spinach | Direct sow | Apr 17 – May 14–6 weeks before last frost (avg. May 29) | Jun 1 – Jun 3045–60 days from seeding |
| Basil | Start indoors | Apr 17 – May 14–6 weeks before last frost (avg. May 29) | — |
| Radishes | Direct sow | Apr 24 – May 152–5 weeks before last frost (avg. May 29) | May 14 – Jun 1420–30 days from seeding |
| Lettuce | Direct sow | May 1 – May 152–4 weeks before last frost (avg. May 29) | Jun 30 – Aug 360–80 days from seeding |
| Onions (sets/transplants) | Plant sets/transplants | May 1 – May 152–4 weeks before last frost (avg. May 29) | Jul 25 – Sep 1285–120 days from planting |
| Broccoli | Transplant | May 1 – May 152–4 weeks before last frost (avg. May 29) | Jun 20 – Jul 2450–70 days from transplanting |
| Cabbage | Transplant | May 1 – May 152–4 weeks before last frost (avg. May 29) | Jul 10 – Aug 1370–90 days from transplanting |
| Kale | Transplant | May 1 – May 152–4 weeks before last frost (avg. May 29) | — |
| Marigolds | Start indoors | May 8 – May 290–3 weeks before last frost (3–4 weeks before setting out; Univ. of Idaho) (avg. May 29) | — |
| Zinnias | Start indoors | May 8 – May 290–3 weeks before last frost (3–4 weeks before setting out; Univ. of Idaho) (avg. May 29) | — |
| Potatoes | Plant seed potatoes | May 15 – May 221–2 weeks before last frost (avg. May 29) | Aug 8 – Sep 985–110 days from planting |
| Marigolds | Direct sow / transplant | May 29 – Jun 12from the last frost to 2 weeks after (Univ. of Idaho) (avg. May 29) | — |
| Zinnias | Direct sow / transplant | May 29 – Jun 12from the last frost to 2 weeks after (Univ. of Idaho) (avg. May 29) | — |
| Broccoli | Fall transplant | Jun 4 – Jun 1810–12 weeks before first fall frost (avg. Aug 27) | Jul 24 – Aug 2750–70 days from transplanting |
| Cabbage | Fall transplant | Jun 4 – Jun 1810–12 weeks before first fall frost (avg. Aug 27) | Aug 13 – Sep 1670–90 days from transplanting |
| Tomatoes | Transplant | Jun 5 – Jun 121–2 weeks after last frost (avg. May 29) | Aug 14 – Aug 27Ends at the first fall frost (Aug 27). Harvest may end early at the first fall frost. 70–90 days from transplanting |
| Beans (bush & pole) | Direct sow | Jun 5 – Jun 121–2 weeks after last frost (avg. May 29) | Jul 20 – Aug 2145–70 days from seeding |
| Sweet corn | Direct sow | Jun 5 – Jun 121–2 weeks after last frost (avg. May 29) | Aug 9 – Aug 27Ends at the first fall frost (Aug 27). Harvest may end early at the first fall frost. 65–90 days from seeding |
| Cucumbers | Direct sow | Jun 5 – Jun 121–2 weeks after last frost (avg. May 29) | Jul 15 – Aug 1640–65 days from seeding |
| Squash | Direct sow | Jun 5 – Jun 121–2 weeks after last frost (avg. May 29) | Jul 15 – Aug 140–50 days from seeding |
| Pumpkins | Direct sow | Jun 5 – Jun 191–3 weeks after last frost (avg. May 29) | Aug 24 – Aug 27Ends at the first fall frost (Aug 27). Harvest may end early at the first fall frost. 80–100 days from seeding |
| Basil | Transplant | Jun 5 – Jun 121–2 weeks after last frost (avg. May 29) | Jul 17 – Jul 2442 days from transplanting |
| Peppers | Transplant | Jun 12 – Jun 192–3 weeks after last frost (avg. May 29) | Aug 16 – Aug 27Ends at the first fall frost (Aug 27). Harvest may end early at the first fall frost. 65–75 days from transplanting |
| Eggplant | Transplant | Jun 12 – Jun 192–3 weeks after last frost (avg. May 29) | Aug 21 – Aug 27Ends at the first fall frost (Aug 27). Harvest may end early at the first fall frost. 70–90 days from transplanting |
| Kale | Fall sow | Jun 18 – Jul 28–10 weeks before first fall frost (avg. Aug 27) | Aug 7 – Sep 1050–70 days from seeding |
| Lettuce | Fall sow | Jul 2 – Jul 166–8 weeks before first fall frost (avg. Aug 27) | Aug 31 – Oct 460–80 days from seeding |
| Spinach | Fall sow | Jul 9 – Jul 304–7 weeks before first fall frost (Virginia Tech) (avg. Aug 27) | Aug 23 – Sep 2845–60 days from seeding |
| Radishes | Fall sow | Jul 16 – Jul 304–6 weeks before first fall frost (avg. Aug 27) | Aug 5 – Aug 2920–30 days from seeding |
| Daffodils | Fall plant bulbs | Jul 30 – Sep 104 weeks before to 2 weeks after first fall frost (our approximation of when soil falls below 60°F; Rutgers) (avg. Aug 27) | — |
| Tulips | Fall plant bulbs | Aug 13 – Sep 242 weeks before to 4 weeks after first fall frost (our approximation of when soil falls below 60°F; Rutgers) (avg. Aug 27) | — |
| Garlic | Fall plant cloves | Aug 13 – Sep 172 weeks before to 3 weeks after first fall frost, while the soil is still workable (SDSU, Illinois, Virginia Tech) (avg. Aug 27) | Apr 20, 2027 – Jun 14, 2027250–270 days from planting |
About the harvest estimates
Each expected harvest window adds the days to harvest from the sources below to the planting window. Days count from sowing seed (or planting seed potatoes, onion sets or garlic cloves) or, where marked, from setting transplants out; “Start indoors” rows have no harvest of their own. Harvest timing varies with variety and weather, and many crops keep producing for weeks after the first picking. For frost-tender crops (tomatoes, peppers, eggplant, beans, sweet corn, cucumbers, squash, pumpkins, basil) the window stops at the first fall frost: harvest may end early at the first fall frost. Flowers and bulbs show no harvest window, and kale has no sourced figure for spring transplants.
Sources: UF/IFAS Extension, Florida Vegetable Gardening Guide (SP103/VH021), Table 1, “Days to Harvest”; University of Maryland Extension, Growing Onions in a Home Garden; University of Maryland Extension, Growing Garlic in a Home Garden; University of Maryland Extension, Growing Basil in a Home Garden.
Cool-season vs warm-season crops in zone 1
- Cool-season (peas, spinach, lettuce, radishes, kale, onions, potatoes, broccoli, cabbage, garlic): tolerate light frost; plant in early spring and again late summer–fall.
- Warm-season (tomatoes, peppers, eggplant, beans, sweet corn, cucumbers, squash, pumpkins, basil, marigolds, zinnias): frost-tender; plant after the last frost once soil warms.
States with large zone 1 areas
In the US, zone 1 occurs only in Alaska (8 ZIP codes in the 2023 USDA ZIP data), so the frost figures on this page come from a small number of ZIP codes.
Frequently asked questions
When is the last frost in zone 1?
Across ZIP codes in USDA zone 1, the median last spring frost (32°F) at the nearest NOAA station is about May 29, with most falling between May 18 and Jun 3. Hardiness zones measure winter lows, not frost dates, so look up your ZIP for a local date.
What are zone 1 winter temperatures?
USDA zone 1 means an average annual extreme minimum temperature of -60 to -50°F (1991–2020), split into 1a (colder half) and 1b.
When should I plant tomatoes in zone 1?
Transplant tomatoes about 1–2 weeks after your last frost (typical zone 1: around Jun 5), once nights stay above about 52°F (Colorado State). Start seeds indoors 6–8 weeks before the last frost (typical zone 1: Apr 3 – Apr 17).
Which states are in zone 1?
Large parts of Alaska fall in zone 1 on the 2023 USDA map. Check your ZIP code, since zones vary within states.
Other zone guides
Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Zone 8 Zone 9 Zone 10 Zone 11 Zone map Frost dates