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Weather Terms for Gardeners: Frosts and Freezes

What's the difference between a frost and a freeze, when mentioned on the weather report?
Answer: Weather reports not only have the power to stir up a whirlwind of mood swings but they can also cause serious cases of confusion—especially when terms such as “frost” and “freeze” are tossed around. To understand the difference, we checked with the National Weather Service (NWS) by the National Oceanic and Atmospheric Administration (NOAA).

frost on flower

According to the NWS, frost is when the temperature of the Earth’s surface falls below 32°F causing the formation of thin ice crystals that can cover the ground and other cold surfaces. Meanwhile, a freeze is when the temperature is expected to remain under 32°F for an extended period of time—generally longer than a frost. Usually a freeze happens in occasions, such as high wind, that prevent frost.

These terms are important to know because both can occur during the growing season and can drastically affect growth. Since a frost alone is temporary, all you may need to do is protect tender plants by covering them or bringing them indoors the night before a frost is predicted. You can then uncover them once the temperature climbs back up during the day. A freeze, meanwhile, generally spells the end of the growing season for tender plants.

Advisories and warnings will be issued when a frost or a freeze is expected to be widespread, so it's a good idea to pay special attention to your local meteorologist in fall and spring, when these weather situations can creep up on you.
Learn more about the effect air temperature and soil have on plants and how they use water in the Smart Gardening Series: Weather and Science and keep your plants healthy and strong in any weather.

The cold weather does not have to hinder your garden’s progress. Discover how to enjoy your garden’s bounty in any weather change with Four-Season Harvest.

Be ready for the winter season with the Horticulture Smart Gardening Techniques: Preparing for Winter.

With each new season there comes new challenges for every gardener whether you are just starting out or you have been gardening for years. To help make sure your garden is at its very best any time of the year check out Planning Next Year’s Garden Value Pack.

Just like knowing the difference between a frost and a freeze, knowing the science behind your growing plants can help any garden thrive. The Horticulture Smart Gardening Guides: Science Matters can help any gardener obtain more insight about the science of gardening.

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