I
used to use this document for my freeze/frost dates:
http://extension.umass.edu/lan...
PLEASE NOTE: at the bottom states "...Station temperature readings are commonly made at a height of
approximately five feet, and actual ground temperatures can be up to 4° F to 8° F less. Thus, ground frost can
occur even when the measured temperature is 36° F...
Because of this I've been using the 36F/10% spring dates. Have I been too cautious?
