The Upland Gardener by M. L. Wells
Jack Frost finally visited the hilltop on the morning of October 16–a good two weeks past the average and three and a half weeks later than years ago. At 30 to 31 degrees Fahrenheit the beets, carrots, kale, radishes and Brussels sprouts were fine–the lettuce was a tad wilted but okay. The local weather man was off by 9 degrees! That’s a bad error at frost time!
There are two main causes for the arrival of frost. In autumn, as the days shorten and the Sun arcs lower in the sky, the temperature drops. At night the ground cools by radiation and any warmth in the air rises. By dawn the temperature at ground level may reach 32 degrees–frost. This is not usually a killing frost and is called a radiation frost.
However, when a huge, freezing air mass arrives from Canada (called a continental polar air mass) moving in from the north or northwest, the temperature can take a plunge, ending the growing season–an advection frost.
So, time to clean up, put away the tools and think about next year’s perfect garden.
M.L. Wells is a longtime Master Gardner with Allegany County Cornell Cooperative Extension