Plymouth, CT planting zone & frost dates
Plymouth is in USDA hardiness zone 6a. The last spring frost usually comes around April 25 and the first fall frost around October 18, for a growing season of about 172 days.
Planting calendar for Plymouth
Dates are counted from the average last spring frost (April 25) 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 28 – Mar 14 Transplant outdoors: May 2 – May 9 |
| Peppers | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: May 9 – May 16 |
| Eggplant | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: May 9 – May 16 |
| Broccoli | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: Mar 28 – Apr 11 |
| Cabbage | Start seeds indoors: Feb 14 – Feb 28 Transplant outdoors: Mar 28 – Apr 11 |
| Onions (sets) | Plant outdoors: Mar 28 – Apr 11 |
| Peas | Sow outdoors: Mar 14 – Mar 28 |
| Spinach | Sow outdoors: Mar 14 – Mar 28 |
| Lettuce | Sow outdoors: Mar 28 – Apr 11 |
| Carrots | Sow outdoors: Mar 28 – Apr 11 |
| Potatoes | Plant outdoors: Mar 28 – Apr 11 |
| Beans | Sow outdoors: May 2 – May 9 |
| Sweet corn | Sow outdoors: May 2 – May 9 |
| Cucumbers | Sow outdoors: May 2 – May 9 |
| Squash & zucchini | Sow outdoors: May 2 – May 9 |
| Basil | Start seeds indoors: Mar 14 – Mar 28 Transplant outdoors: May 2 – May 9 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 23 (8 weeks before the average first fall frost on Oct 18).
Useful for zone 6a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 12 | Apr 25 | May 10 |
| First 32°F frost in fall is before | Nov 1 | Oct 18 | Oct 4 |
How to read it: in spring there is a 10% chance of a frost after May 10, so that is a safe date for tender plants. In fall there is a 10% chance of frost before October 4. A hard freeze (28°F) usually ends around April 13.
Hardiness zone by ZIP code in Plymouth
- 06782 zone 6a
Nearby cities
- Wolcott zone 6b, last frost Apr 26
- Bristol zone 6b, last frost Apr 25
- Waterbury zone 6b, last frost Apr 26
- Torrington zone 6a, last frost May 8
- West Torrington zone 6a, last frost May 8
- Naugatuck zone 6b, last frost Apr 18
- Southington zone 6b, last frost Apr 26
- Plainville zone 6b, last frost Apr 25
Questions
What growing zone is Plymouth, CT?
Plymouth is in USDA Plant Hardiness Zone 6a (average extreme winter low -10°F to -5°F), according to the USDA 2023 map.
When is the last frost in Plymouth?
The average last spring frost (32°F) in Plymouth is April 25. There is still a 10% chance of frost until May 10.
When can I plant tomatoes in Plymouth?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 2 – May 9. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Burlington, CT (USC00060973), 16.9 km (10.5 mi) from the city center, elevation 154 m, based on 24 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.