Monday, October 8, 2012

Yep, that was a “Hard Freeze” by Tina Ligon

Dill covered with Ice

I think it is a safe assumption that all of us mountain gardeners have had a “hard freeze” by now. I was curious about the terms frost, soft vs. hard freeze and a few other terms that describe those temperatures and conditions that occur around the freezing point of water, 32 F/ 0 C. With a background in science, I am familiar with the behavior of water as it approaches the freezing point but what about these other terms.

Late blooming Daylily

After a little research, it looks like these terms mostly come from meteorologists and the agricultural community. Plus the terms only seemed to be thrown around in the Spring and Fall, we don’t hear much about a frost warning when there is a foot of snow on the ground. Although I learned, it is that frost on snow that leads to higher avalanche danger in certain conditions. Here are some general terms and definitions that I found in the Farmer’s Almanac that seem to be in alignment with National Weather Service guidelines:
FROST: Damage depends upon length of frost duration.
LIGHT FREEZE: 29 degrees F to 32 degrees F / -2 degrees C to 0 degrees C. Tender plants killed with little destructive effect on other vegetation.
MODERATE FREEZE: 25 degrees F to 28 degrees F / -4 degrees C to -2 degrees C. Wide destruction on most vegetation with heavy damage to fruit blossoms and tender semi-hardy plants.
SEVERE FREEZE: 24 degrees F / -4 degrees C and colder. Heavy damage to most plants.
It is all interesting information but seems to be a moot point when we experience a >50 F drop in one day (78 to mid-20s at my house) here in Colorado. Within the next 24-48 hours I saw lows around 18. So needless to say I wasn’t out there trying to cover and protect tender vegetation, the game was over for this year.

Ice crytals on Cotoneaster

Below are a few CSU Extension links to some great reminders about some items to take care of in the Fall to put our gardens and landscape to bed for the winter. Plus enjoy the pictures of the beauty associated with those icy mornings.

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