To Plant or Not to Plant, That Is the Question!

It’s curious to note that many gardeners in our region believe that the date from which we can safely plant our annuals and vegetables is the Victoria Day long weekend. If this date is generally acceptable in Southern Canada, it’s not necessarily so in the rest of the country, and even less so in higher elevations or far from the river.

So how do you figure out which date will work this year? I’ve even had frost at my home in Quebec City on June 7!

Photo: Getty Images Signature

At What Temperature Can We Plant?

Some plants are more resistant to the cold than others. Perennials, shrubs, conifers, etc. – in fact, hardy plants – are all able to tolerate a little frost. – in fact, hardy plants – are all able to tolerate a little frost: there’s no reason not to plant them as early as May.

The opposite is true for vegetables and flowers grown in warm climates: tomatoes, peppers, beans, impatiens, begonias, etc. They come to a standstill when night-time temperatures drop below 10°C (50°F). There’s no point in planting them early: not only will they stay put until temperatures warm up, but exposure to the cold will delay their growth by around 2 weeks. However, some vegetables and annuals are not bothered by cool nights, as long as there’s no frost: cabbages, onions, carrots, snapdragons, marigolds, carnations, etc. They can be planted as soon as there’s no more frost on the horizon.

Photo: Getty Images Signature

How to Determine When the Risk of Frost Has Passed?

Don’t rely on the old belief that the risk of frost disappears immediately after the last full moon in May: there have been too many exceptions in recent years. Instead, I rely on weather forecasts. Here’s how.

Go to a reputable weather website and enter the name of your municipality. This brings up a page giving the day’s temperature. Scroll down the page to “Long-term trend”, where you’ll find the forecast for the next 6 days. If the temperature stays above 12°C, you can plant everything, even chilly vegetables and annuals. If the temperature drops below 12°C, but remains above 0°C, you can plant the hardier vegetables and annuals, but wait before planting the more chilly ones.

Photo: Getty Images Signature

There’s one last check. Check the forecast for the next 14 days to make sure it’s not predicting near-freezing temperatures for the second week. Granted, the 14-day forecast isn’t very reliable, but if it shows a significant drop in temperature, why take any chances?

If cool temperatures prevent you from planting, repeat the process in a week’s time. And again in another week, if necessary.

That’s it! Thanks to increasingly accurate weather forecasts, we’re better able to determine a safe date for planting. But it doesn’t have to be this week!

Larry Hodgson published thousands of articles and 65 books over the course of his career, in both French and English. His son, Mathieu, has made it his mission to make his father’s writings accessible to the public. This text was originally published in Le Soleil newspaper on May 31, 2008.

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

2 comments on “To Plant or Not to Plant, That Is the Question!

  1. Hi Larry,
    There is a new gardening website for the North Shore of Nova Scotia, and we have just published an article on last frost dates. It might be of interest to you?

  2. Laurie Macdonald

    Great advice ! Planting too early however tempting it may be not only delays some growth by weeks but one early my tomatoes and peppers were actually stunted and produced only half of previous years harvest. I’m waiting, patiently !

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