Frost dates for Groton, CT
When the last spring frost and first fall frost usually come, and when to plant, from 30 years of NOAA weather records.
Last spring frost
April 8
typical year
Safe to plant
April 22
frost is over in 9 of 10 years
First fall frost
November 2
typical year
Growing season
207 days
frost-free, typical year
Frost watch this week
Tonight's and the next six nights' lows from the National Weather Service forecast for the station's location. Frost: 32°F or colder. Possible frost: 33–36°F, mostly in low spots on clear, still nights.
When to plant
Counted from this page's frost dates. Warm-season crops wait for the safe-to-plant date.
| Crop | Start indoors | Plant outside | Fall planting |
|---|---|---|---|
| Cool-season crops | |||
| Peas | – | Mar 11 – 25 | – |
| Spinach | – | Feb 25 – Mar 18 | Sep 7 – 21 |
| Lettuce | – | Mar 11 – Apr 1 | Sep 7 – 21 |
| Radishes | – | Mar 11 – Apr 22 | Sep 21 – Oct 5 |
| Onions | – | Mar 11 – 25 | – |
| Potatoes | – | Mar 18 – Apr 1 | – |
| Carrots | – | Mar 18 – Apr 8 | Aug 10 – 24 |
| Beets | – | Mar 11 – 25 | Aug 24 – Sep 7 |
| Kale | Jan 28 – Feb 11 | Mar 11 – 25 | Aug 24 – Sep 7 |
| Broccoli | Jan 28 – Feb 11 | Mar 25 – Apr 8 | Aug 24 – Sep 7 |
| Cabbage | Jan 14 – 28 | Mar 11 – 25 | Aug 24 – Sep 7 |
| Garlic | – | – | Sep 21 – Oct 12 |
| Warm-season crops | |||
| Tomatoes | Feb 25 – Mar 11 | Apr 22 – May 6 | – |
| Peppers | Feb 18 – Mar 4 | Apr 29 – May 13 | – |
| Cucumbers | – | Apr 22 – May 13 | – |
| Zucchini | – | Apr 22 – May 20 | – |
| Pumpkins | – | Apr 22 – May 13 | – |
| Green beans | – | Apr 22 – Aug 24 | – |
| Sweet corn | – | Apr 22 – May 20 | – |
| Basil | Mar 18 – Apr 1 | Apr 29 – May 6 | – |
Onions: from sets. Green beans: until 10 weeks before the first fall frost. Garlic: harvest next summer.
The year at a glance
Start indoors Plant outside Fall planting
The chance of frost, by date
| 1 year in 10 | Half of years | 9 years in 10 | |
|---|---|---|---|
| Spring frost after | April 22 | April 8 | March 28 |
| Fall frost before | October 18 | November 2 | November 15 |
Frost here means 32°F or colder. Read across: in 1 year in 10, spring frost carries on past the first date, which is why that date is the safe-to-plant date.
Hard freeze (28°F)
A hard freeze kills most garden plants, even hardy ones. The last one in spring usually comes around March 29 (April 7 in a late year), and the first one in fall around November 14.
Where these dates come from
NOAA weather station GROTON, CT US (USC00063207), 1991–2020 climate normals. It's the nearest station for 5 zip codes, all within 7 miles:
06335, 06339, 06340, 06355, 06375
Planting dates follow common university extension advice; your local extension service can fine-tune them for your soil and microclimate.