Hardiness of Iridaceae

[MarcR]

I have noticed that The Saunders, while they were with us, rated most genera of Iridaceae a zone or two hardier than Sunset and other 'experts, and they were correct.

I am wondering why the 'experts' are so conservative.

[Maggi Young]

An interesting question and, playing "devil's advocate' I'll give several opinons as to why!

Firstly, the Saunders were really immersed in the culture and habitat of those plants and so knew, probably better than anyone else, what the conditions are that those plants require and/or tolerate.

Secondly,  "the experts" may be  cautious in order to deter others wanting to grow them, especially if said "experts" also show these  plants ( yes, I am a very suspicious old lady!!) and thirdly,  these "experts" may be selllers and may feel caution is advised to avoid too many customers complaining if the plants die!  ( oh yes, I'm suspicious and sceptical in great measure!)

Of course,  it might also have been that the Saunders, bless them, who were often selling seed in such plants, wanted "us" to think they were easier than they truly are!!!
Now then if those comments haven't  put the  cat  amongst the  pigeons to generate further discussion, I don't know what will!

 

[Darren]

You should see Innes's 'World of Iridaceae' for examples of extreme conservatism. Most Cape bulbs are listed as needing minimum 10C, which is not my experience at all. However - if they had sufficient winter light I am sure they would be happy with this. Here we try to keep them cool and just 'ticking over' while the light is poor in winter.

I gifted some Cape bulbs to Myerscough college some years ago and they grow them under lights and with some heat. Ferraria flower weeks earlier than mine and on more compact plants even though they are clones of my plants.

[MarcR]

Thank you Maggi, and Darren for your replies.
Maggi, I especially appreciate your insights!

[Vinny 123]

With any species that is uncommon in cultivation, but widespread in nature, the habitat plants are likely to be growing across one or two different zones and possibly show different degrees of hardiness.
Hardiness zones themselves are also a major over-simplification. I remember the "big freeze" of 1962-63, but no more than it being icy for what seemed ages (I was 4 years old). I have also experienced the -20C (-40C wind-chill) that persisted for a few days in January 1987. These were in N Essex.
Many species of birds were all but wiped-out, if they did not migrate, but I have no idea what plants were especially hit - I do not recall it getting much mention, if at all, in 1987.

[MarcR]

Vinny 123,

Thank you for sharing a very sensible perspective.

I still wonder 'What is in the works ?' when Sunset Garden Books, Botanica, Hortus 3, and John Bryan [noted author of books on bulbs] all agree that a genus', or species' hardiness ends 2 zones warmer than the Saunders say it ends; and the Saunders consistently prove to be correct.

[Vinny 123]

I still wonder 'What is in the works ?' when Sunset Garden Books, Botanica, Hortus 3, and John Bryan [noted author of books on bulbs] all agree that a genus', or species' hardiness ends 2 zones warmer than the Saunders say it ends; and the Saunders consistently prove to be correct.

Folklore?
I have no evidence to confirm that in any area of horticulture, but have plenty in other hobbies.
Once a "fact" appears in print, it is cast in stone, so to speak - they just get repeated. The "problem" is that people accept a "fact" and don't want to tempt fate.

I have loads of Zantedeschia odorata seedlings so left them in an unheated greenhouse over winter - perfectly OK down to -5C. Now just starting to go dormant.

[MarcR]

Thanks Vinny 123!

Sounds about right

[Diane Whitehead]

Microclimates can make a big difference, even within a single garden.

[MarcR]

Dianne,

Excellent Point It's even true of my garden.  However in the case of Irid hardiness, I have neighbors, whom I know through Falls City Garden Clubs; and are also growing Iridace at different altitudes and exposures. On seeing my plants, many fellow club members started growing their own.
so these Irids are growing, where the experts say "they cant", for several people in very different microclimates within Zone 8.