MISSOULA — While most of us have seen our first frost (even light freeze) of the season already, a widespread hard freeze is looking very likely both Monday and Tuesday mornings!
If you have sensitive vegetation, this will be a “season ender” for gardens unless precautions are taken.
I spoke with Missoula County Department of Ecology & Extension’s Plant Clinic Coordinator Sandy Perrin. She says tender plants like tomatoes, peppers, squash, basil and cucumbers can be negatively impacted with a frost, but will die with the first freeze (32°). Annual flowers like impatients, coleus, dahlias and sweet potato vine, too.
On the flip side, some cold-hardy crops such as kale, carrots, spinach and root crops are more resistant and can withstand a frost and even a light freeze (29°-32°)… it can actually improve flavor! Annual flowers such as geraniums, mums, petunias may have flowers killed by frost, but the buds that haven’t opened are usually ok.
There are a few things you can do this time of year:
First off, harvest! If your produce is ready, there’s no need to keep it on the plant and risk damage. Most fruit trees (pears, apples & plums) tolerate a light frost, but below 28°, better get them picked. Most will ripen off the tree, too.
If you’re looking to extend the season, you’ll have to cover tender plants with frost blankets or tarps to trap heat and protect them from freezing temperatures. If you can bring the plant inside, even better!
Perrin says we’ve had a pretty good growing season this year… lots of peaches, cherries and plums due to a mild winter and several seasons without producing. It was a GREAT berry year. She says we definitely needed more precipitation, though.
* Quick reminder of the difference between frost, freeze and hard freeze if you need it:
Frost happens when ice crystals form on surfaces when air temps range from 33°-36°.
A freeze happens when the temp drops to 32° or lower and will result in significant damage to unprotected plants especially if the temp remains at or below freezing for several hours.
A hard freeze typically occurs when the temp reaches 28° or colder for at least an hour… usually more. This means that most seasonal vegetation will be destroyed. There’s also the chance for possible damage to unprotected outdoor plumbing/undrained sprinkler systems, etc.
