Every year, I use the date of May 12th as my estimated last spring frost date. My tomato plants and hot pepper plants cannot be planted outside before this estimated frost date. If I planted my new starter plants outside before the estimated frost date, I’d risk losing them. Frost will kill them. In addition to this timing, usually the soil is not warm enough outside either; so, there is a period of time to acclimate your plants outdoors before you actually plant them in the ground.

There are many resources on the web where you can search for what the spring frost date is in your area. Some of the sites provide the ability to just enter your zip code to see where it falls. For example, try this site provided by almanac.com. When I enter my zip code, a date of April 27 is produced as my last spring frost date.

April 27th is too early for me. Based on years of growing tomato and hot pepper plants from seed, I feel this date is far too risky. May 12th is a safer date, and this is the date I use to count backwards on my calendar to determine when to sow my seeds. See my prior posts on that. So I use that last spring frost date to count backyards for sowing seeds, but also my estimate as to when I might be able to put my starter plants grown from seed outdoors to acclimate them after the frost has definitely passed.

In addition to frost, tomato and hot pepper plants like warmth. While the last spring frost may have passed, the ground is still cold and not completely warmed up outside. So, planting the starter tomato plants waits a bit longer – till end of May (Memorial Day). Following this timing has worked out for me over the years.

What typically happens is we may get a early warm up. It will feel fantastic outdoors and your soul and body will feel as though it is time to plant. But I caution you to be aware, things always change quickly. I am always amazed at how fast Mother Nature changes her mind.

Not only does Mother Nature change her moods, but she also has the amazing ability to provide a new twist on the weather and climate. For example, I think this past winter has been a mostly a windy winter with no snow! We’ve had no snow until one day this week in March. Before that, there were days that felt like spring! My husband is amazed he has not plowed the driveway once this entire winter of 2023.

Last year, it was a drought year during the summer months of 2022. That was not helpful to my container gardens during the summer when my tomatoes and other plants were outdoors growing fully. Anyhow, my point is, only Mother Nature truly knows when the last spring frost date will be, and I swear, last year, I don’t recall experiencing a hard frost in the spring. I usually write it down on my wall calendar when it actually occurs to track information. Climate change, Mother Nature’s closest cousin, throws in his own blend of ideas on how to mess with our planning and tracking. You get the idea. Climate change has been changing some of our past gardening routines and timing.

The key thing is if you get anxious, to remember to watch your local weather stations during late April to early May, and they usually will give you a heads-up if a hard or light spring frost is coming. And if you decided to tempt fate and put your plants out into a garden before frost and a later frost happens, you could protect your seedlings perhaps by using an appropriate method to cover the plants. This may be okay for plants not so affected by frost and cold, but I find tomatoes really should be put out when we are sure it is warm enough outdoors and after the estimated frost date. Exposing them to frost situations will only cause your plant to start off wrong. Frost will kill the plants that need warmth the most, like tomatoes and pepper plants, as well as any tender non-hardy plants.

Between May 12th, which again is my personal estimated spring frost date, to the end of May, this is the time period where I harden off my tomato starter plants outdoors. It gives you a couple weeks to expose them to the outdoor elements gradually. The starter plants are put outdoors on a table to be exposed to the outdoor elements each day and taken back in. If you decide you want to start moving them into their permanent container gardens, patio pots, and anything other than a garden in the ground, I suppose you could move the pot into your garage if a frost arrives, but I don’t recommend planting them outdoors earlier than Memorial Day (end of May). It just gets the plants cold and stressed.

With all of this said, I’m referring to my location in Broad Brook, CT which is Zone 6b. You may live in a part of Connecticut that is warmer, or perhaps you have some unique setup or micro-climate. When you look at sites providing frost date information, they explain in detail the calculated risks of frost dates and all the factors around these estimates.

I know when I first tried to determine my last spring frost date information, it drove me crazy. There were so many variations, it is truly frustrating. If you are new to gardening, ask your nursery person or neighbor who’s a gardener what date they may use as their estimated guide for their last spring frost date. I’m sure you will get various responses on that. But always be aware, plants have different needs. Not all vegetable plants are equal. Some vegetables may be exposed to cooler temperatures, so if you ask, be sure to ask for the type of plant you want to transplant into your gardens or container gardens and patio pots.

As I have noted, hardening off is required for indoor grown seedling plants. They must be moved outdoors to get them acclimated. You must protect them from harsh sun, gusty winds, and cool temperatures. Usually, you start by putting them in a shady location and move them more each day for a few hours to sun.

This is my date list of how it goes for me:

May 12th – My Estimated Spring Frost Date; Watch the tv news around this timeframe, see if they announce it then or before.

May 15 – May 26 – Harden off the Starter Plants outdoors for a few hours every day.

May 22 week – People pick up starter plants from me and harden them off at home (or they secretly plant them early because they feel it is safe for them! LOL).

May 29 – Start planting all outdoors in pots and in the ground and enjoy watching them grow till they produce fruit in the summer! May 29th is the date for 2023 Memorial Day.

Have a good day,

Cathy Testa
Broad Brook, CT
Container Crazy CT