Hippeastrum species - low temperatures

Tony Avent tony@plantdelights.com
Mon, 30 Apr 2007 14:09:09 PDT

We had a devastating freeze of 22 degrees F after two weeks in the 80's 
and many trees in full leaf.  I had several clumps of hippeastrum 
(including H. 'Voodoo') in full bud that were left unprotected in the 
freeze ( 5 nights in a row).  All have since opened regularly showing no 
effect of the freeze.  I'm impressed...wish I could say the same for 
many of our native trees.

Tony Avent
Plant Delights Nursery @
Juniper Level Botanic Garden
9241 Sauls Road
Raleigh, North Carolina  27603  USA
Minimum Winter Temps 0-5 F
Maximum Summer Temps 95-105F
USDA Hardiness Zone 7b
email tony@plantdelights.com
website  http://www.plantdelights.com/
phone 919 772-4794
fax  919 772-4752
"I consider every plant hardy until I have killed it myself...at least three times" - Avent

Lee Poulsen wrote:
> Yes, I have experience with Hipps and low temperatures (such as the 
> ones you ask about). As you probably know, California, in particular 
> southern California, had a fairly severe freeze for our climate. Many 
> locations, even close to the ocean saw temperatures below freezing on 
> one or more mornings in January. Several nurseries in northern San 
> Diego County that were only about 3 miles away from the ocean measured 
> lows of mid-20s F for four mornings in a row. I even saw frozen leaves 
> on plants in beachside neighborhoods in San Diego, which is one of the 
> few USDA zone 11 locations in mainland USA. It was a severe radiation 
> freeze with zero air movement in many locations leading to very small 
> microclimates (nanoclimates?) just about everywhere. I just heard from 
> several growers of Plumeria in Orange County who had them killed on one 
> side of their house and untouched on another side of their house. Even 
> at my house, my main exposed outdoor thermometer read 26 deg F. on the 
> coldest morning. Nevertheless, in my sizable side yard (where I grow a 
> lot of things since it gets the cooler morning sun), I think the 
> temperature only reached maybe 30 or 31 deg. F. Nothing I had there, 
> including seedlings showed any indication of freezing weather at all. 
> Clivias in my backyard (where my main thermometer is located) had 
> considerable leaf damage, while 6-month-old Clivia seedlings in the 
> sideyard acted as if nothing happened. That is also where I had all my 
> mature Hippeastrums as well as some 2 year old Hipp. seedlings. Even 
> though I tried to protect most of them from winter moisture, since 
> we're having a record-breaking low-rainfall year (3 inches total for 
> the year), the Hipps have been kept dry all winter. Even so, 2/3 of 
> them never lost their leaves. And none of the leaves were frozen on any 
> of the Hipps that had them. All of them appear to have survived the 
> freeze without any signs that they even cared. And even the species 
> that I worry about and keep in my unheated greenhouse experienced 
> temperatures in the high 30s on a couple of the mornings. (Nothing in 
> there was harmed or hurt. I have a few Episcias, but I've already 
> learned that they act like they've been frozen whenever they experience 
> temperatures in the low 40s F. So I always bring them inside before 
> then.)
> So if this is helpful to you, then good. More likely this will confirm 
> to some how foolish I and a number of other plant hobbyists in Southern 
> California are in how and what we try to grow outside in this climate.
> --Lee Poulsen
> Pasadena, California, USDA Zone 10a
> On Apr 30, 2007, at 9:37 AM, Stephen Putman wrote:
>> It has been a really peculiar weather year.
>> I am wanting to get some of the bulb pots moved out of the greenhouse,
>> but the weather still is too hot inside some days and too cold(?)
>> outside some days.  Does anyone have experience with Hippeastrum 
>> species
>> and minimum night temperatures?  I have always used 50 F as a nominal
>> minimum. Anybody have experience with, say, 45? or 40?
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