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Noon Edition

Frost: Know Your Zone, Climate And Microclimates

In 2003, Philip Harnden wrote an informative book called  A Gardener’s Guide to Frost. The author advises readers to be well informed about their local weather, climate, and the zone in which they garden.

Gardeners also need to be aware of the frost dates in their region. This means the date of the last frost in the springtime and the first frost in autumn.

These dates are like the bookends of the growing season.

The Importance Of Knowing Frost Dates

The date of the last spring frost tells us when it is usually safe to set out tender annual plants. Tender flowering annuals, such as petunias and geraniums, will be damaged or killed by a frost if they are planted prematurely.

Naturally the date of the last frost varies from year to year, so gardeners need to be tuned in to the difference between “usual” and “average” frost dates.

The number of frost-free dates available in a growing season is also a helpful statistic. Again this number of days varies from year to year because frost could arrive unexpectedly.

Additionally, Harnden reminds us that all gardeners need to understand the microclimates within their own gardens and thus recognize the spots in their yard that are most vulnerable to frost.

Jack Frost may be coming to your garden repeatedly in the next few weeks so be careful that a few days of warm weather do not seduce you into planting tender annuals too early.


Philip Harnden, A Gardener’s Guide to Frost: Outwit the weather and extend the spring and fall seasons, (Willow Creek Press, Minocqua, Wisconsin, 2003).

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