After a pretty slow start to the winter(ish) season, a good hard freeze the past couple of mornings have taken us to full dormancy. 20°F on the morning of December 11th and 23° on the 12th appear to have taken care of what leaves were retained after mild freezes in mid-November. Below are some of our plots in Fredericksburg. Pear, fig and pomegranate.
We commonly get asked how we calculate winter chilling for the Hill Country. We actually use a modified formula that begins counting winter chilling hours beginning with the first 32°F reading, then we count all hours below 45F°. Yes, subfreezing hours really do little to overcome dormancy, and yes even temperatures above 45F° are quite efficient at breaking rest, but on the average, this method seems to characterize the season pretty well. We are actually using equipment in the field that is somewhat dated. Ten years ago, these basic “Hobo” units were state of the art, but many newer versions of these data loggers are now on the market. Pictured here is our standard temperature and relative humidity station. We have the hobos set to record data every 15 minutes, so they can actually stay in the field for quite some time and hold several months worth of data. We download temperature and relative humidity data every couple of weeks to keep track of where we are, and the software will give us a graphic chart and save raw data in an excel file. Pretty handy, and they are paid for. As noted, its been slow start, but here is hoping for a cool and wet winter.