We
are fast approaching the last frost free date of October 15 in Franklin County
and many home gardeners, eager to either have homegrown tomatoes for
Thanksgiving or loath to discard any possible foodstuff, are looking at their
green tomatoes.
Frost,“ killing frost,” freeze warnings, a “killing freeze” - what is the difference? In casual conversation the terms frost and freeze are often interchangeable but there is a very real difference. Frost and freeze are two distinct phenomena. These terms take on significance when they are associated with the growing season.
FROST
According to the National Oceanic and Atmospheric Administration (NOAA), frost is the formation of thin ice crystals on the ground or other surfaces in the form of scales, needles, feathers, or fans. Frost develops under conditions similar to dew, except the temperatures of the Earth's surface and earthbound objects falls below 32°F. A frost advisory is issued when widespread frost formation is expected over an extensive area. Surface temperatures are usually in the mid-30’s. If a frost period is sufficiently severe to end the growing season (or delay its beginning), it is commonly referred to as a "killing frost."
Dr.
Katharine B. Perry, North Carolina Extension Service, has compared frost and
freeze conditions for protection of horticultural crops noting frost and freeze
protection methods are based on preventing or replacing radiant heat loss.
Because
frost is primarily an event that occurs as the result of radiational cooling -
heat loss at night - it frequently occurs with a thermometer temperature in the
mid-30’s. A radiation frost happens when a clear sky and calm winds (less than
5 mph) allow an inversion to develop. An inversion occurs when the heat
radiating from the earth rises and causes the cooler air above to be pushed
down, and temperatures near the surface drop below freezing.
Covering
plants before the sun sets may be protection from frost as this can help retain
heat near the plants.
According
to NOAA, a freeze is when the surface air temperature is expected to be 32° F
or below over a widespread area for a significant period of time. Use of the
term is usually restricted to advective situations or to occasions when wind or
other conditions prevent frost.
Dr.
Perry explains than an advective, or windborne, freeze occurs when a cold air
mass moves into an area bringing freezing temperatures. Wind speeds are usually
above 5 mph and clouds may be present. Attempts to protect plants are very
limited under these conditions.
A
"killing freeze" may be used during the growing season when the
temperature is expected to be low enough for a sufficient duration to kill all
but the hardiest herbaceous crops.
According
to NOAA, freeze warning are issued during the growing season when surface
temperatures are expected to drop below freezing over a large area for an
extended period of time, regardless whether or not frost develops.
GREEN
TOMATOES
Oops!
Okay, you were enjoying the weather and forgot. Now what? There's always fried
green tomatoes or you can store them to ripen up later.
Kansas State also suggests roasting them for eating warm or cold, using in side dishes or freezing in small batches to use throughout the winter.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-fZsoYLSzdwYqxklPz6Vl44wRdLexMHs0JraCV48ZylLm1TnovNwZEjJCmezKHMvgeoaGsOMB0Fr7KArvmPGmpdbAnvgW_4CGx3QSVaUfYqnxAzFzF7Xn0R23uEZPpTzCQg41qcuF5_wi/w425-h234/recipe.png)
HARVEST AND STORE TO RIPEN
Pick
and store your mature green tomatoes and let them ripen up on counter top or
windowsill but not in the refrigerator. Ron Wolford, University of Illinois
Extension horticulturist, notes that green tomatoes can be harvested before a
predicted frost.
“You
can tell when a tomato is nearing maturity by its light green, almost
translucent, appearance,” according to Barb Fick, horticulturist with the
Oregon State University Extension Service. “Tomatoes that are not in this
'mature green' stage won't ripen.”
Kansas State Extension Master Gardeners note that "not all green tomatoes will ripen off the vine. They must have reached a "mature green stage." Look for full-sized tomatoes with a white, star-shaped zone on the bottom end of the green fruit. Also, on maturing green tomatoes, skin at the blossom end may be beginning to change color from green to pink or red." Use immature green tomatoes in recipes such as salsas or fried.
Ron
Wolford recommends removing the stems, washing and drying the fruit. Wrap each
tomato in newspaper and place them in a single layer on a shelf or in a box.
You can also put them in deep straw or just lay them in a box so that they are
not touching. Check tomatoes every few days and discard any that show signs of
rot.
Tomatoes
will ripen satisfactorily in the dark, according to Fick, and sunlight is not
needed; however, temperature is important. Storage temperature should range
from 60 to 70 degrees. They will ripen over a period of three to four weeks.
Picking
and storing the mature green tomatoes in mid-October means there's a good
chance you can have some tasty, home-grown tomatoes for the Thanksgiving
celebration.
CKagan, Master Gardener
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