Last Frost and the Growing Season

NOAA

As the spring season carries on, warm weather eventually gives way to the start of the growing season. Here are some key facts about gardening weather in Connecticut…

Average last frost in Connecticut: April 26th

As we move into the end of April, the average low temperature rises into the lower 40s. Although we have had frosts into the month of May, it’s pretty safe to start planting those plants by May 1st. The average growing season in Connecticut is about 166 days. This means that the first fall frost tends to happen around October 9th. Be careful what you read though. Different websites will give you a last frost date anywhere from mid-April to mid-May.

Let’s talk about some key facts before we clear up the confusion… Using Hartford as the location, the average low temperature for March 28th is 32 degrees. Keep in mind that frost can occur when the air temperature falls below 38 degrees.

The average low temperature is 38 degrees by April 16th.

Average is an important word
Even though the average low may be 38 degrees, temperatures could easily fall back into the 20s, just as lows in the 40s are completely normal as well for mid-April. This is part of the reason why the last frost date occurs after the last day with an average low below 38 degrees.

What about records?
Well, Hartford has fallen to 38 degrees as late as June 10th. Does that mean you shouldn’t plant anything until June 11th? Of course not! As a general rule, April 26th is a good estimate when it comes to the last frost. If you are planting something that is very sensitive to the cold, you should probably wait until later in May for planting. On the other hand, if you have the ability to keep the plant warm, whether it be with covering them or temporarily bringing them inside, feel free to plant them earlier. Also, if you live along the shoreline or in the downtown part of a city, usually it’s rare to see a frost after late April.

Just keep these dates in mind and don’t forget, we live in New England. It’s a place where it can snow in October, but be 60 degrees in January. Flip around to the spring and remember that it can be cold or even snowy well into the month of April.