Frosts and ultimately freezes are an inevitable function of autumns in Montana.  Sometimes they come earlier than expected, and sometimes without warning bringing garden production to a screaming halt.  But quite often in this area, the first frost comes in mid-September and is followed by a few more weeks of adequate growing temperatures.  Usually at this time of year, there are plenty of green tomatoes on the vine and other frost sensitive crops that have not quite finished for the season.  Click HERE for a list of crops and their relative hardiness.

When weather forecasts predict temperatures to dip to 30oF or lower, it is time to take action to prepare for some frost protection in your garden.  There are numerous strategies to employ to protect your plants, whether you want to protect an individual pepper or eggplant, a few cucurbits, or an entire row of tomatoes.  Follow the following steps to achieve various levels of frost protection…



    1.  Ensure that the plants are well watered.  Moist soil retains heat much better than dry soil, and dry plants can be more susceptible to frost damage


      2.  Move containerized plants to a warmer location:  next to the house, under a patio cover, in a garage.


     3.  Cover the plants before sunset to capture the ground heat radiating upward at night.  A number of different materials can be used to provide varying levels of protection.

a.      Floating row cover or spunbonded polypropylene can offer 2-4o F of protection


b.      Clear polyethylene hung over PVC hoops can provide 3-6o F of protection



c.       Conventional blankets over the PVC hoops can provide additional protection


d.      Hanging Christmas lights (non-LED type) under polyethylene covered hoops can reach greater than 6o F of protection.  This also provides an added bonus of creating a festive look in your garden.  The deer will thank you.



Other strategies can be used, such as Wall-of-Waters over small individual plants, draping blankets over the plants, and plenty of other creative ideas.  If you use conventional bedroom blankets, you will need to ensure that the blankets remain dry.  All coverings need to be removed or opened during the day to allow for the soil to absorb radiant heat, and to ensure that the plants do not overheat during potentially hot days.


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