Jane, It was NEVER my intent to suggest that Alstroemerias are reliably hardy in Zone7! My only intent was to caution Steve that he might loose them if planted in SE Michigan without protection. You asked where my info came from and I told you. I will agree that the hardiness recommendations in any of those sources fails to account for microclimates; and, tends to be conservative. MarcR [zone 8b] On 4/30/2022 12:00 PM, Jane McGary via pbs wrote: > I don't want to repeat my entire taped rant about hardiness "zones," > so will only note that when I lived near Estacada, in the Cascade > foothills, an area Marc Rosenblum probably knows, my home appeared to > sit on the line between Zone 8 and Zone 1 on the USDA map. Most > winters the low was around 15 F, but about every fourth winter, colder > temperatures occurred, the lowest being minus 6 F in the historic cold > snap of 1990-91, which killed even some native plants all along the > Pacific coast. My doubts expressed in an earlier post are admittedly > subjective, based on a lifetime (75 come this July) of observation > from central California to interior Alaska and 9 plant-hunting visits > to western and Andean South America, as well as 30+ years of > optimistic, experimental gardening. Unlike Hortus III and the RHS, I'm > not using statistical methods, but the book "How To Lie with > Statistics" comes to mind. > > I do want to correct myself: when I wrote A. pulchella, I meant A. > psittacina, which Garak's post mentions. Also note his phrase "for > single nights," which may mean that the soil did not freeze to the > depth of the tubers or even the growing points. Like many other > geophytes, alstros can delve deeply. I once dug down to see how A. > umbellata (a snow-zone central Andean) grew, and it was underneath > about 30 cm of loose, dry talus and another 15 cm of fine, slightly > moist sand (in January, the dry southern midsummer). That leads to > another topic, the influence of rocky habitat in providing moisture to > plants in arid climates, where fog or dew condenses on the rocks and > trickles down. Whatever the books tell you, that is not "baking." > > Jane McGary, Portland, Oregon, USA > > > On 4/29/2022 11:24 PM, Marc Rosenblum via pbs wrote: >> Jane, >> >> I estimated that most Alstromerias have a hardiness threshold of >> about 0 F [-18 C]. >> Garak's -11C falls well above that threshold. I based my estimate on >> Sunset, L.H. Bailey's Hortus III, and the RHS garden Plant Index. >> >> On 4/29/2022 8:53 PM, Garak via pbs wrote: >>> I can confirm that Ligtu hybrids, psittacinas and modern >>> horticultural hybrids can tolerate unprotected, snowless frost of >>> -11°C for single nights. Unlike the Ligtus, modern hybrids will lose >>> overground growth to late frosts, but usually return soon after. I >>> agree that my mixed winter climate is far more difficult for them >>> than true continental climate would be. The psittacina actually has >>> more problems with my dry summers, it's a really thirsty plant. >>> > _______________________________________________ > pbs mailing list > pbs@lists.pacificbulbsociety.net > http://lists.pacificbulbsociety.net/cgi-bin/… > Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net>