Leo Martin of Phoenix, Arizona wrote: > Bob posted a link to a photograph of a USDA climate zone map from 1936. > Were the temperature ranges for each zone the same then as they are now? One thing about USDA hardiness zones, be they from 1936 or 2017: they refer to the hardiness of woody plants. Nothing else. They have proven very useful in the cultivation of other plants, but do not take into account other important factors, notably the annual pattern of precipitation, which is just as important as temperature to the successful culture of bulbs in the open garden. I always wonder why dwellers in the southwestern deserts of the US (notably Phoenix!) don't use oncocyclus irises as bedding plants. There is, however, a ray of hope for PBSers living in summer squelch: The great English rock gardener and bulb specialist, E. B. Anderson, compensated for his damp summers by planting his Mediterranean bulbs where the roots of deciduous trees could reach them. This gave them plenty of moisture in winter and spring while the trees were still dormant, but very dry summers (in the soil) as the trees came into active growth and removed soil moisture. _______________________________________________ pbs mailing list pbs@mailman1.ibiblio.org http://pacificbulbsociety.org/list.php http://pacificbulbsociety.org/pbswiki/