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RE: Northern/cold weather hardiness

  • Subject: RE: Northern/cold weather hardiness
  • From: irischapman@aim.com
  • Date: Wed, 01 Apr 2009 09:11:20 -0400

It has long been argued that hardiness is divided into many sectors
based on the different climates that plants are grown in, and genetic
constitution of the individual plants. Certainly ther are plants that
do well only in very specific gardens, ie: the garden of origin. Some
thing like 'Romantic Evening' would seem to do very well in mild
climates, such as Oregon/California, and sporatically outside this
area. That it hangs on for you certainly says something, as it is one
that I would not have expected to grow in your area. 

Having said that, I have to agree with you on general hardiness. I also
know that there are plants that do well in many different climates. I
exchanged some notes with Walter off list, and a number of plants that
do well for him also grow well here. 'Garden Bride', my own very hardy
cold climate plant, also does well in Texas. So, there are plants that
are hardy and vigorous in many different climates. It would be nice
if we had a way of identifying these plants. A few that I'm aware of
are 'Celebration Song', 'Garden Bride', 'Tuscana Villa', 'Vibrations'.
In addition, most of Walter's introductions do well for me in a cold
climate, even thought they were hybridized in a hot dry climate, much
different from my climate. Thius is not true of all hot dry climate
introductions. I would suspect a number of my cold hardy introductions
would also fare well in hot dry areas. Every coup
le of years we get
extreeme drought in summer, so this goes into mix of selecting plants
for introduction. 

There are three different sets of cold hardy genes. One of these set
also confir drought hardiness to the plant. So plants with these sets
of genes will be more likely to be viable both in cold climates
(Canada/Northern USA) and dry conditions, eg Texas, Arizona. If we had
a weighted voting system for AIS awards, more of these plants would
show up with awards. As it is the weighting is towards plants that do
well in the "iris Paradise" areas. 

So, there are some plants that are basically hardy, period. We need to
be able to identify these plants, so they can be recommended to iris
novices. People's enthusiasm is turned off by a bed of dead expensive
plants. Turned on and fueled by a bed of happy blooming plants. 

I have had a lot of responses to the trial offer, from some excellent
gardeners who are eager. this bodes well for the trial. Some second
thoughts include, what would happen with these same plants in a hot dry
area , such as Arizona and Texas? 

The plants that have better responsiveness to the environment will do
well in all sorts of environments. A number of plant defensive actions
are triggered by a number of stressors, few plant defensive
mechanisms are extremely specific. 

Plants that put up flower stalks very early in spring will
survive and
perform very well in areas with hot springs , that burn off flowers,
but will be frozen out in areas that get late frosts. So it is easy to
select against plants that have E or VE classifications if you have
late frosts. 

There is also several types of dormancy. This will make some plants
more hardy in some areas versus others. What I would like to award
system to do is award plants with good flowers, that do well in a wide
variety of growing areas. 

Sandra, can you identify what is different in your garden/culture that
would result in such good survival, that is not seen in other in your
climate. Planting on the south side of a house or wall is one thing
that can make a difference in a cold climate. Many plants that don't
survive in colder area, is not because they are killed by cold, but
because temperatures for triggering bloom and increases are not met in
the growing season. Thus they slowly fade out. The temperatures for
bud set and this seems to be related to the triggering of increases,
would seem to be between 15-21C. Thus if summer minimums don't exceed
15C for 6 nights, no bud set and limited increase. Same if temperatures
don't go below 21C for 6 nights in a row. At least this is what my
current experiments/research suggests. In both of these circumstances
we would see gradual decline over several years and eventual death of
plant. Of course, this is ve
ry much a cultivar variable, so some will
make do with cooler or warmer trigger temperatures. 

For this last reaon, I'm encouaring trial participants to record
min/max temperatures
on a daily basis during growing season

A lot of various rambling. 

Chuck Chapman 




  Northern/cold weather hardiness  (Chuck) 


Posted by: "SandraB" 






  Tue Mar 31, 2009 9:22 am (PDT) 



Chuck that list of plants provided in the AIS bulletin was I believe
taken from people who grow those irises in their cold climate gardens.
I personally don't believe in providing people 

a list of 'cold hardy' irises and because of that I didn't provide a
list to Kate of irises that are cold hardy. I actually didn't agree
with much of that article myself based on my fifteen years experience 

growing TB's iris in my garden. Like I said previously I have very
little problems with TB irises surviving the winter if they are planted
early enough. In addition, once they survive that first winter then
they rarely have a survival problem after
.. If you are talking about
irises that continue to grow and increase in later years then I don't
believe you are necessarily talking about cold hardiness, but rather
irises that 

aren't vigorous and that is not necessarily specific to cold climates.

There are certain irises that may just do better with certain soils, a
certain climate during the growing season (e.g. hot summers, dry vs
wet, etc.) and certain management practises. 


For instance, Romantic Evening, that iris, is the worse
grower/increaser I have. It has bloomed the majority of years I have
had it (I think over four winters now and I moved it once in that
time), but it barely increases and it always blooms on short stalks
with misshappen flowers. Now I could say that iris isn't cold hardy,
but is it actually a good grower anywhere ? 


As for blooming consistently, I have learned from Linda in US Zone 7,
that it is the fluctations in temperature in the spring that often kill
the bloom on the iris and I believe Donald has also mentioned the same 

thing - so are we going to say irises that don't bloom consistently
aren't cold hardy when they do the same sort of thing in Texas ? I
actually think for your climate Chuck, Linda would be able to help you

than for someone in a real cold climate for genetics that are less s


Also, I would like to make a comment about medians, especially dwarf
bearded irises. In the past five years I have purchased a lot of SDB
irises (because they take up less space) and I have probably lost just
as many of them in portion to the numbers I have purchased as I do
TB's. So does th 

at mean the SDB are now getting less cold hardy (there
are some of them that are sure a lot less vigorous) ? 


I recall talking to you about Rhonda Fleming - that iris did well for
me. I believe it would meet your five year trial definition, but your
experience with that iris was that it was tender - so I think other
factors are 

involved here. 




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