Michel,

You don't need to build a heated greenhouse to safely winter your trees in a
simulated zone 6 or 7 temperature. A cold frame will do the job nicely with
no added heat. Take a look at this article on Reiner Goebel's website:
http://rgbonsai.com/wintering.htm
He uses a cold frame in Toronto, which is Zone 5 I believe. I use a similar
cold frame here in Spokane, Washington, also Zone 5. The coldest it ever
gets in my cold frame is about +25 degrees F. That is way warmer than the
average maximum low for zone 6 or 7 (-10 degrees F for zone 6 and 0 degrees
for zone 7). Once built the cold frame costs nothing to operate, the heat
from the earth keeps the temperatures moderated.

Regards,
Roger Snipes
Spokane, WA. Zone 5-ish

----- Original Message -----
From: "Michel Bourgeois"
What I don't like here is only the climate. We have a lot of snow in the
winter, 3 to 4 feet and I live in a 3b zone so, I let you guess the damage
it can do to you Japanese Pines at -35C! And in the spring... all the snows
melt during the day and in the next night it goes to -15C! Poor little root!

This winter I will build a greenhouse and try to simulate a 6 or 7 zone...
it will cost a LOT of money to warm it!

************************************************** ******************************
++++Sponsored, in part, by Bob Pastorio++++
************************************************** ******************************
-- The IBC HOME PAGE & FAQ: http://www.internetbonsaiclub.org/ --
+++++ Questions? Help? e-mail +++++