Waiting for the last frost date

tomato seedlings
Tomato seedlings on top of my fridge, waiting for the day they can start hardening off and finally be transplanted into their permanent home outside.

Every night, I’m checking the weather forecast to see if Toronto is expecting a frost. It’s that time of year, when you’re not getting a frost every night, but you’re not guaranteed above-freezing temperatures every night, either. With lots of seedlings waiting patiently under grow lights until they can be hardened off and transplanted, and a whole lot of flower and vegetable seeds yet to be planted outdoors, I have a countdown on for the day that I know all risk of frost has passed. Some vegetables like carrots have instructions to not plant until risk of “hard frost” has passed, while others are more picky and want the soil to be a specific temperature (15° C seems to be in high demand).

Knowledge of my last expected frost date was obviously required, so I found a chart which has Toronto’s last frost date as May 9. How that can be later than Ottawa’s last expected frost date of May 6 has me baffled, but what do I know of weather patterns? Now I have a clear schedule in mind, and a better idea of when all those seedlings and seeds will finally make it outside.

You can find your own last frost date from sources such as Veseys or here, so you, too, can mark it in your calendar. The countdown is on!

Pepper and snapdragon seedlings waiting for the risk of frost to pass.

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  1. LM says

    There is nothing mysterious about last frost dates: they are nothing more than a mathmatical average…. the last frost can occur before or after that date. What’s more, frost damage can occur between 32 and 36 degrees F. The important thing is to be prepared to protect your plants any night where temperatures dip.

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