My grandparents used to sit in their kitchen and talk about the weather in a much different way than we do now. We say things like “it’s going to be a nice day” or “it will be a cold one”. When they talked about temperature it was in relation to how it effected the garden, the animals, and their work on the farm. One of the lost conversations is about frost. It is not just 32F (or 0C). They used three main terms for different freezing temperatures
This is the commonly known frost. It begins 32 F (0C). This is where water starts to freeze. Some plants die quickly such as tomatoes and most other annuals. Covering the plants overnight usually protects them.
A hard frost occurs at 25F(-3C). Some say it has to last for 4 hours to effect the plants but in my experience this is not an exact science. If the soil is warm it might take 4 hours but if it has been freezing during the day and dips down a few more degrees at night it does not take four hours for plants to die. Watering the plants while the temperature is dropping can help them survive. Keep in mind water temperature also makes a different. Nice warm water out of a dugout will help more than cold well water. On a small garden patch covering the plants with slightly insulated material can work (e.g.use bed sheets instead of plastic).
A Killing Frost occurs when the temperature drops to 19F (-7C). The common definition is when all the plants die but if you have a lawn you know that -7 isn’t going to kill it. A killing frost that occurs at the beginning of the growing season is battled with heated greenhouse or cold frames. In the fall it marks the end of gardening season.
My grandparents and I lived at a high altitude and saw frost come in any month of the year. It made gardening difficult. When I moved further from the mountains I was amazed at how warm it stayed at night. Gardening was far more fun and productive in the warmer environment. Wherever you are growing plants it is important to know all you can about the environment they are in including what to expect when frost comes. Happy Gardening!