cold duration

I tapped into the climate records from the University of Georgia cold duration calculator.  So, it's not just my imagination, but this past winter has been a particularly prolonged cold winter.  This winter our purple heart plant died, but this plant survived the past 5 winters outdoors.

Has prolonged cold temperatures altered when trees bloom or the arrival of other spring markers? My backyard record keeping could be better, but it looks like a ~19 day delay of spring markers when comparing 2010 with 2009.

Bradford Pear              20-MAR-2010    15-FEB-2009    33 day delay 

Carpenter Bees             28-MAR-2010    09-MAR-2009    19 day delay

Acer palmatum leaf out     02-APR-2010    14-MAR-2009    19 day delay

Flowering Dogwood          03-APR-2010    21-MAR-2009    13 day delay

Asian Wisteria             06-APR-2010    24-MAR-2009    13 day delay

Carolina Cherry Laurel     07-APR-2010    14-MAR-2009    24 day delay