I live in USDA climatic zone 4 and the first japanese maple I acquired for bonsai was overwintered in a cold room of my basement where the temperature was 40 F minimum . It grew very well during the summer 2004 and was overwintered for the second winter in a cold greenhouse with 3 in thick sterofoam padding around the nebari and sterofoam pot and finally covered with a thermal cloth. My other native trees did not have the special nebari padding. In the spring the tree looked well with nice buds ready to open. In may, the buds never opened and the plant died. The root system was very well developped and healthy looking and was as large and as long as the trunc and branches. All my native trees remained very healthy up to date.
I took the tree to the plant pathology diagnostic laboratory where I worked part time for 30 years for confirmation of the disease by the pathologist in charge. The next day I was told that microscopic examination of the xylem vessels at different parts of the trunc showed collapsed cells that blocked the vessels and was definitely caused by what seemed a severe climatic temperature stress which is often observed on non-adapted trees of my climatic zone . No parasitic pathogens were later isolated from the tree.
I learnt my first lesson in fiding out that japanese maples are not hardy in zone 4.
So, for the benefit of bonsaists who want to grow trees in climatic zones in which there is lack of hardiness or lack of a dormant period , they should know that trees may suffer from a physiological disease which eventually causes death. Maybe it has already happened to people who have posted in the “dying bonsai” section of this forum without really knowing the real cause of death.
Non-adapted trees can suffer climatic stresses caused by very low temperatures during the winter or sudden drops of temperatures (sometimes more than 10 degrees celcius during a single day in zone 4) most often during late spring and early summer when the plants grow vigorously. It could also be a combination of both or even other factors like too much heat and dryness. They may not die after the first few stresses but if these factors re-occur often enough as the years go by, they will eventually die. I have personnally experienced many cases of these diseases during my 30 years career in my plant diagnostic laboratory for zone 4 only, and also with my first japanese maple as I explained earlier after it’s second winter where I had given it much more protection than my native maples.
This is a typical example of what can happen to a non-hardy tree as is the case of japanese maples that you may want to grow in USDA climatic zones 1,2,3 and 4, for where they lack hardiness and in zones 11 for a lack of a dormancy period.
Some of the published hardiness zones data for japanese maple give zones 5 to 9 as shown in these references:
http://hort.ifas.ufl.edu/trees/ACEPALE.pdf
http://www.cce.cornell.edu/programs...r/zonesumm.html
http://sis.agr.gc.ca/cansis/nsdb/cl...shrubs2000.html
http://wabcweather.abclocal.go.com/...day=1®ion=NE
http://www.mountainmaples.com/WS4D_...d&Condition=is&[Class]StoreFrontID=3&Condition=and&Condition=contains&[Class]Alpha11=e&SortBy=[Class]Text1&RecordsPerPage=20&Database=Class&BreakTable=20&Page=1&LinkField=[Class]Text1&Results=results(comp).html&Results-1-Record=testproduct.html&Results-Table=results(comp).table&Table-Color-Even=
http://www.monbonsai.com/lesbonsais...og/cat_erab.htm
http://www.monbonsai.com/lesbonsais...og/cat_rust.htm
But, this does not mean that you cannot grow japanese maple in these zones but bonsaists must realise they need much more protection than native trees and have to be grown for at least part of the season in either a well equiped cold room in your basement, a controlled environment greenhouse or a controlled environment growth cabinet, all of which are very expensive to buy and to maintain. The bonsai nursery where I live grow them in complex greenhouse sections. They also have to be protected from other temperature stresses in the summer.
A forum member named jportock mentioned in another post, and I quote : “
Then you should also consider that if you are able to mimic the conditions that any species lives in it doesn't matter what the actual climate is in your locale. Something that I have had drilled into my brain since I began reading this forum is that the care of various trees greatly depends on where you live. I have not heard anyone say that there is some species that will die in some geogrphic location no matter what conditions you keep it in.”
This is very true because with the technology we have developped today, you can grow a plant anywhere in the world, even on the moon. Most botanical gardens grow plants from all over the world in their greenhouses. In Montreal, Canada there is a place called the “Biosphere” where they have created the four seasons and from tropical to arctic conditions with the plants and animals that live in thoses different sections. In fact, you can grow a coconut tree or palm tree in Alaska or an apple tree in Miami or Hawai, but to “mimic” the growing conditions you need very expensive equipment as I said above.
As for zone 11, you will also need some equipment to give the tree a cold period every year otherwise it will die.
What is said above concerns all trees and shrubs like trident maple, vine maple etc.that are non-adapted or not hardy to climatic zone 1,2,3 and 4 . The information on hardiness for all trees can easily be found in the web.
I hope this important information will be usefull for those who live in the climatic zones concened.
Al Devaux, retired plant pathologist