Lewiston, Maine: planting zone & frost dates
Lewiston is in USDA plant hardiness zone 5b, where the average coldest winter night reaches -15 to -10°F (-26.1 to -23.3°C). The typical last spring frost is around Apr 30 and the first fall frost around Oct 13.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 6 | Oct 5 |
| Typical planning date (30% risk) | Apr 30 | Oct 13 |
| Median (50%) | Apr 25 | Oct 19 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station LEWISTON, ME (USC00174566), 2.3 mi (3.7 km) from the city center and 118 ft lower than the city center (-36 m). Record used for the 1991–2020 normals: 11 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Lewiston
All 1 ZIP code covering Lewiston is in zone 5b.
ZIP codes in Lewiston and their zones
| ZIP | Zone | Share of city land |
|---|---|---|
| 04240 | 5b | 100.0% |
Vegetable planting calendar for Lewiston
Dates are counted from the 30%-risk frost dates above (last frost Apr 30, first frost Oct 13). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 5 – Mar 19 | May 7 – May 21 | — | — |
| Pepper | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Lettuce | Mar 19 – Apr 2 | Apr 16 – May 7 | Apr 2 – May 14 | Aug 4 – Sep 1 |
| Green Beans | — | — | May 7 – Jun 11 | Jul 21 – Aug 4 |
| Sweet Corn | — | — | May 7 – Jun 4 | — |
| Zucchini & Summer Squash | Apr 2 – Apr 9 | May 7 – May 21 | May 7 – May 28 | Jul 21 – Aug 4 |
| Cucumber | Apr 2 – Apr 9 | May 14 – May 21 | May 7 – May 28 | Jul 21 – Aug 4 |
| Carrot | — | — | Apr 9 – May 14 | Jul 21 – Aug 4 |
| Onion | Feb 5 – Feb 19 | Apr 2 – Apr 16 | — | — |
| Potato | — | Apr 2 – Apr 23 | — | — |
| Basil | Mar 19 – Apr 2 | May 14 – May 28 | May 14 – Jun 4 | — |
| Spinach | — | — | Mar 19 – Apr 16 | Aug 18 – Sep 15 |
| Kale | Mar 5 – Mar 19 | Apr 2 – Apr 23 | Apr 2 – Apr 23 | Aug 4 – Sep 1 |
| Broccoli | Mar 5 – Mar 19 | Apr 16 – May 7 | — | Jul 21 – Aug 4 |
| Peas | — | — | Mar 19 – Apr 9 | Aug 4 – Aug 18 |
| Eggplant | Feb 19 – Mar 5 | May 14 – May 28 | — | — |
| Cabbage | Mar 5 – Mar 19 | Apr 2 – Apr 16 | — | Jul 21 – Aug 4 |
| Radish | — | — | Mar 26 – May 14 | Sep 1 – Sep 29 |
| Strawberry | — | Apr 2 – Apr 23 | — | — |
| Beets | — | — | Apr 9 – May 21 | Aug 4 – Aug 18 |
Nearby cities in Maine
- Portland — zone 6a, last frost May 1, first frost Oct 9
More: all Maine cities · other zone 5b cities: Madison, WI, Des Moines, IA, Aurora, IL, Fort Collins, CO, Naperville, IL, Rockford, IL, Elgin, IL, Greeley, CO
Lewiston gardening questions
When is the last frost in Lewiston, ME?
Plan around Apr 30. At NOAA's Lewiston, ME station, 2.3 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 25, and after May 6 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 11. The last frost is fairly predictable here: only 25 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Lewiston, ME?
Start seeds indoors Mar 5 – Mar 19 and set transplants outside May 7 – May 21, once nights stay above 50°F and the soil is near 60°F. That leaves 166 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Lewiston?
About 177 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 159 days, and in 1 year in 10 it runs 198 days or more. In fall there is a 10% chance of frost by Oct 5 and a 30% chance by Oct 13.
When should I plant a fall garden in Lewiston?
Count back from the first fall frost (Oct 13): transplant broccoli Jul 21 – Aug 4; sow kale Aug 4 – Sep 1; sow lettuce Aug 4 – Sep 1; sow radishes Sep 1 – Sep 29. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Nov 1. How the math works: succession and fall planting.
Did Lewiston's hardiness zone change on the 2023 map?
No. Going by the zone that covers most of the city's land, Lewiston is zone 5b on both the 2012 and the 2023 USDA maps (PRISM/OSU ZIP listings). About 42% of U.S. ZIP codes kept their half-zone in 2023. Why the 2023 map is warmer.
How does Lewiston compare with Portland, ME?
Lewiston is zone 5b and Portland is zone 6a. The typical last spring frost in Lewiston (Apr 30) comes about the same time as in Portland, ME (May 1), 32 miles away, and the first fall frost is Oct 13 versus Oct 9. Lewiston sits about 299 ft higher, which explains part of the gap. The two cities use different NOAA stations.