Protecting Vegetables from Frost

Protecting Vegetables from Frost

Monday, March 31, 2003

Paul Schnare


If you want to get one up on your neighbor and harvest the first ripe tomato of the season read on.  In order to have early ripe tomatoes or other frost susceptible vegetables you must be willing to protect these plants whenever a late spring frost or freeze is predicted.


Tomatoes and other garden vegetables can withstand freezing temperatures as low as 28 to 30 F.  On the other hand, they cannot withstand frost.  Frost is crystallized dew that forms on the plant surface.  These crystals destroy plant cell walls when they melt.  This damage, if severe enough, can cause death.


Frost can occur at forecasted temperatures near 40 F, well above freezing.  For example, if your garden is in a low area, cold air will cascade down the surrounding hills and accumulate in the low areas at night.  Temperatures may be as much as ten degrees colder in the valley than on top of the hill.  In addition, skies must be clear and winds calm for frost to accumulate.


If you plant tomatoes, peppers, beans, eggplant or other frost susceptible plants in your garden early in the season, you must be able to protect them from frost.  There are several products available for gardeners to do just that.


Using hot caps over individual plants will protect them from frost.  To protect rows of vegetables from frost, gardeners often cover the row with a frost blanket.  Both hot caps and frost blankets should be removed from the vegetable during warm days.  Then when frost conditions are predicted, the vegetables should be covered at night.


Gardeners can also use another product called a Wall-O-Water that can protect plants from late freezes and frosts.  Use one Wall-O-Water around each plant.  Sunlight warms up the water in the Wall-O-Water.  At night, heat from the water radiates to the plant and keeps it from freezing.  The Wall-O-Water also protects plants from frost.


You can also use sheets or blankets over your plants.  Make sure the blanket is not so heavy that it damages your plants.  You may also use a plastic sheet over plants.  Just make sure that the plastic sheet does not touch the plant.  I have seen leaves touching cold plastic damaged from freezing.


Finally, if for some reason you did not get protection over your plant during a night when frost occurred, you may save your plants by sprinkling them with water early in the morning before sunlight shines on your garden.  Continue sprinkling until sun up and until temperatures climb above freezing.  Sprinkling may keep your plants from being damaged. 


With some early spring effort you may win the prize for the first ripe tomato in the neighborhood.