It would be interesting to know what type of thermometers are being used to record the temperatures. It has to be a professional max/min thermometer located at the location of the plants. I have been recording temps for the weather service for years and I know how important it is to record temperatures for accurate reports. When I hear reports of damage above 32 degrees I am very suspect of where this thermometer is located. Any entries on this should actually included thermometer locations and their accuracy. Joe, Oceanside, CA On Jan 16, 2013, at 12:40 PM, "richard" <xerics@cox.net> wrote: > I have a few two year old Alstromeria seedlings. Two of the A. magnifica > suffered leaf damage and perhaps more. The single A. ligtu was fine. My > temperatures did not get below 36 degrees F but there was significant > radiational cooling due to the open sky and lack of wind. > Richard in Vista, CA > > -----Original Message----- > From: pbs-bounces@lists.ibiblio.org [mailto:pbs-bounces@lists.ibiblio.org] > On Behalf Of Nathan Lange > Sent: Wednesday, January 16, 2013 12:22 PM > To: Pacific Bulb Society > Subject: Re: [pbs] Freezing bulbs: Duration vs. low temperature > > > I would like to hear about people's experiences with Alstroemeria cold > tolerance. I had many plants left outside unprotected since last night's > forecasted low of 33F by the National Weather Service was a full 6 degrees > off from reality (it was actually 27F). Well, that's not entirely true; I > was curious to see what would happen. > Undoubtedly, the plants can survive down into the 20's and this will vary by > species but I wonder how cold most species/cultivars of Alstroemeria can go > before damage becomes apparent. > > I routinely use inverted black plastic pots for cold protection with great > success on a number of species. The trick is to use a second pot over the > first. It should go without saying that all pot covers must be removed the > next morning. Covering the foliage may not be the only concern. If you are > growing plants in plastic pots that are out in the open, all the roots at > the edge of the root ball are in contact with the plastic pot and highly > susceptible to night time temperatures. > > Floating row covers are widely available here in Northern California. > When it becomes to cumbersome to elevate the material off the plants, I just > throw a second and sometimes a third layer over whatever I'm covering. The > key is to create as many layers of insulating air as possible. That being > said, positioning is everything and blocking a plant's view of the overhead > sky could easily save it. Just moving an uncovered potted plant under the > eave of a building or canopy of a tree could easily prevent damage depending > on the circumstances. > > Don't forget to water your plants. Plants are generally more susceptible to > cold damage if they are also water stressed. Cold weather arrives with dry > air and this has certainly been the case this past week in California. I > watered a lot of dry plants yesterday. Remember to water early in the day > and keep all water off the foliage at night. Any water left on leaves at > night can freeze and do significant damage. The alternative is to pretend > that you are growing citrus and run the water overhead all night long to > keep the temperature of the ice from going too far below freezing. Of > course, controlled water stress *prior* to cold can generate some beneficial > tolerance to cold temperatures in some species but this should not be > confused with water stress *during* the cold period. > > Bright sunny mornings are not at all helpful. They just make you feel > better. Freeze and chilling injury damage can be greatly exasperated by > bright sunny mornings accompanied with rapidly rising temperatures. This has > been the case here in Northern California for almost a week. If I had to > choose, I would move an uncovered potted plant under the west or north eave > of a building and completely avoid the east and south exposures. If I had a > marginally cold tolerant specimen planted in the ground shrouded in floating > row covers, I would still definitely block the morning sun from hitting it > with cardboard or some other barrier. In some instances, this is almost as > important as covering the plant. > > But it all depends on the weather and everyone should have at least one > min/max thermometer to know what's going on outside. I can't imagine growing > anything without them. > > Nathan > > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/ > > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/