Qian, B., Zhang, X., Chen, K., Feng, Y. and O'Brien, T. 2010. Observed long-term trends for agroclimatic conditions in Canada. Journal of Applied Meteorology and Climatology 49: 604-618.
Reviewed here: http://www.co2science.org/articles/V13/N39/C2.php
What was learned
Qian et al. say their results indicate "a significant lengthening of the growing season due to a significantly earlier start and a significantly later end of the growing season," and they say that "significant positive trends are also observed for effective growing degree-days and crop heat units at most locations across the country." They also report that "the occurrence of extremely low temperatures has become less frequent during the non-growing season, implying a more favorable climate for overwinter survival," and they find that "the total numbers of cool days, frost days, and killing-frost days within a growing season have a decreasing trend," so that "crops may also be less vulnerable to cold stress and injury during the growing season." In addition, their work reveals that "extreme daily precipitation amounts and 10-day precipitation totals during the growing season have been increasing," and that "significant trends associated with increased availability of water during the growing season are identified."
RW: In my very first posting http://cdnsurfacetemps.blogspot.com/2010_02_01_archive.html I noted the increase in the growing season since 1900, longer by some 30 days. Nice to be vindicated.