Bonsai Study Group Forum

General Category => General Bonsai Discussion => Topic started by: Judy on October 19, 2013, 07:49 PM

Title: Quercus suber overwintering
Post by: Judy on October 19, 2013, 07:49 PM
I have been reading up about cork bark oak to determine the best overwintering scheme for mine in zone 5.  I have not been able to find any solid information about whether or not this tree requires a dormancy period.  I keep a EU olive overwintered in a setup inside, and was wondering if that would be more appropriate for the oak as opposed to a cold greenhouse environment.  The winters here are long, and may be harder on the tree than a short cold spell would be. 
Title: Re: Quercus suber overwintering
Post by: augustine on October 21, 2013, 09:09 AM
Judy,

There should be a minimum temperature listed in Brent's catalog, evergreengardenworks.
Title: Re: Quercus suber overwintering
Post by: Judy on October 21, 2013, 02:34 PM
thanks augustine,
He lists it at 0ºF minimum low temp.  But I've also read that they will not live below 40 for a number of days in a row.  That's quite a difference.  I wonder if plants in zone 10 (where this is listed to) actually get a dormant period. 
If that 0º is correct (and I don't doubt that he would know) then I won't have any trouble with it in my cold, but temp regulated greenhouse.
Title: Re: Quercus suber overwintering
Post by: 0soyoung on October 21, 2013, 04:56 PM
The USDA zones are based on minimum average temperatures. Zone 8, which is the hardiness zone for cork oaks has min temperatures of 10F to 20F. One reference I've seen says that 15F is fatal.

One would need to look elsewhere to determine if cork oaks have a dormancy requirement or not. They are grown quite successfully in San Diego landscapes where it rarely, if ever, gets as cold as 40F, however. So, it seems plausible that it might be kept indoors during the winter as is frequently done with tropical trees.
Title: Re: Quercus suber overwintering
Post by: Gaffer on October 21, 2013, 08:44 PM
Hi Judy
It should over winter in your greenhouse nicely. Needs a little wintering , but if it gets really cold just put a 100watt lightbulb in the green house and you should be fine.
Good luck
Qualicum Brian
Title: Re: Quercus suber overwintering
Post by: Judy on October 22, 2013, 07:21 AM
Thank you both, I will try the greenhouse this winter, seems like it will (fingers crossed) be fine.
Title: Re: Quercus suber overwintering
Post by: John Kirby on October 22, 2013, 11:16 AM
I overwintered one for a friend in the Head House we had for plant propagation. Temps rarely got below 35. It did fine. It is fully Mediterranean, it might take a cold night, but not an extended cold.
Title: Re: Quercus suber overwintering
Post by: Judy on October 22, 2013, 04:31 PM
I wonder if they actually need dormancy?  I would rather not kill it in the cold,( it'll be 28-35 in the greenhouse for a couple of months running) if it doesn't really need to have a dormant period.  My olive is happy without dormancy, and it's a mediterranean...
Title: Re: Quercus suber overwintering
Post by: John Kirby on October 22, 2013, 05:10 PM
It doesn't need a real dormancy. Treat it like your Olive .
Title: Re: Quercus suber overwintering
Post by: Judy on October 23, 2013, 09:06 AM
Thanks John.  Safer is better... ;)