Friday, September 19, 2014
First Frost 2014
Local weather forecasts warned of frost last night. We found that hard to believe since the evening was both warm and overcast. Early this morning our thermometer registered 38 degrees F so assumptions were made that we had escaped again the first fall frost. This afternoon a trip to the back garden revealed that frost had lightly visited during the night. Some of the butternut squash leaves showed the signs of just a little frost. Part of this leaf is dead while some of it continues to perform life functions. Butternut squash needs cold nights to set its sugars and last night surely moved that process along. Many huge squash remain in the field improving their flavor in response to the cold.
Nearby, this leaf shows a frost curled edge. Try as we might, no progress has been made in gaining insight or understanding about the actual workings of frost. Cold sinks toward the ground and is moved about by air currents. Plants nearest the woods displayed no frost damage while those at greater distance from the trees were hit. Cold air slides down the nearby ridge and swirls about hitting some spots and missing others.
Our wake up temperature was 38 causing me to believe that we had missed a frost. Later my error was discovered since there is no reason to believe that the lowest overnight temperature is reached just before dawn. Air masses are constantly moving about so the coldest air could have visited here during the night. Lack of visible morning frost does not mean that frost was absent.
Here the higher younger leaf is undamaged while the lower leaf is lightly burned. Conventional wisdom says that frost settles downward from the sky so one would expect the higher leaves to burn first. The outline of the upper leaf can be seen marking the edge of the burn on the lower leaf. How did this happen?
Our lower garden near the house appeared undamaged at first look. Two frost burned heliotropes were discovered inside of the stone square adjacent to stone paths. We have previously seen the protective effect of heat stored in stones but on this night cold swept in the opening in the wall and moved across these two low plants. We could find no other damage inside of the walled square.
Cleaning up frost destroyed plants is a horrible task. Foul odors, slippery leaves and the mass destruction combine to make the cleanup difficult. Our preference is to move tender plants to the compost pile while they are still green. All of the peppers and some of the basil were composted yesterday afternoon. The remaining basil was covered and stands ready to supply one more pesto dinner.
Working outside now is nearly perfect. Clear blue skies warm the surface air quickly. As more planting beds are cleared of weeds, the garden is beginning to look like it is ready for the next crop. Early afternoon finds the tiny flying biting insects feeding voraciously since the cold nights signal an end to their season. Those insect bites have us looking forward to the first hard killing frost. It will end many of the plants but it will also end the annoying bugs.