Global warming causes changes in gardening hardiness zones

A Japanese azalea, whose usual bloom time is October, has given us its most prolific bloom in December and January, despite a number of freezes


For decades, those of us who garden in the U.S. have known with certainty which of the ten gardening hardiness zones we were in, and which of the sub-zones. That has changed now. The National Arbor Day Foundation has recently updated the zones, and there are significant changes in that several zones have become warmer. My own zone, already warm, has been changed to reflect an even hotter climate.