Dear Jane: Duration of subfreezing temperatures is an important factor although I am not aware of any study on this topic specifically related to geophytes. Higher elevations in the Southwest get as cold as Chicago but the extremes don’t last as long as they do in Chicago. Native plants collected for trial have a challenge in northern Illinois winters. Don’t give up yet. On a related topic, I brought in your donated mystery bulbs from my new cold frame when overnight temperatures dropped into the lower teens. They had weathered three weeks of cold daytime highs and overnight lows. Currently 6 new Narcissus cantabricus are in flower. On Sat, Jan 13, 2024 at 11:08 AM Jane McGary via pbs < pbs@lists.pacificbulbsociety.net> wrote: > After no significant frost this year, the Pacific Northwest is > experiencing a sudden severe cold snap. My bulb collection is exposed to > ambient temperature, though covered against moisture. Everything is now > frozen solid. The temperature is not expected to rise above freezing for > about five days. What I wonder is, once a plant in growth is frozen, > does it matter how long it remains frozen? Almost all the plants in my > bulb house have previously survived about 20 degrees F for three days. > Is five days going to be worse? Or do I just give up on all > possibilities of survival because the plants were in unusually early > growth? There are about 1,200 different species concerned. I did bring > emerging seedlings into the garage before the freeze hit, but no > protection was possible for the plunged pots in the bulb house. Any > cover would have blown off in the present high winds -- the falling snow > is whirling around as the wind gusts constantly shift. > > Explanations of hardy plant response to prolonged freezing welcome. > > Jane McGary, Portland, Oregon, USA > > > _______________________________________________ > pbs mailing list > pbs@lists.pacificbulbsociety.net > https://lists.pacificbulbsociety.net/cgi-bin/… > Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> > PBS Forum latest: > https://pacificbulbsociety.org/pbsforum/index.php/… > _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net https://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> PBS Forum https://…