USDA Hardiness Zone 6b
Frost Dates for 06237 — Columbia, Connecticut
Averages from Willimantic Windham Ap, Ct US, the nearest reporting station, 6.3 miles away.
Plant tender crops after April 28, and expect the first autumn freeze around October 13. That leaves about 167 frost-free days.
- Last spring frost
- April 28
- First fall frost
- October 13
- Growing season
- 167 days
- Hardiness zone
- 6b
50% probability
50% probability
frost-free
-5 to 0°F annual low
Planting calendar for 06237
| When | What to do |
|---|---|
| February 17 – March 3 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| March 3 – March 17 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| March 31 – April 14 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| April 28 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by July 21 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by September 29 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| October 13 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after April 28 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in Columbia, Connecticut are past their last freeze. Harvest before October 13, which leaves roughly 167 frost-free days.
ZIP 06237 sits in USDA hardiness zone 6b, meaning the average coldest night of the year falls between -5 to 0°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.