North American Fruit Explorers mailing list at ibiblio

[dwoodard@becon.org]

Derry, I would start to worry about your exposed apple rootstock pots, 
especially the M9.

Your St. Julien and Mazzard will probably be OK if they are in the ground.

If not, everything depends on the amount of snow cover. If it's a solid 2 
feet above the pot tops my guess is that you are OK for now.

I think St. Julien A is fairly hardy, to about zone 5b in the ground. 
Ordinary Mazzard I wouldn't trust beyond 6b, in normal circumstances.
You should be OK. The only thing I might worry about is whether the 
temperatures fell abrubtly from continuous above freezing for a long
time, to your current temperatures. Even well after domrancy begins,
full coldhardiness takes some time to develop. However, it does
usually peak roughly mid January.

A lot depends on how thick the snow cover is.

The late Isaac Brock Lucas had a sheltered fruit garden at Markdale, 
Ontario, in zone 4a I believe. He had reliable *heavy* snow cover 
(downwind of Lake Huron and Georgian Bay) and he successfully grew
apples on M9 and pears on Quince A.

With open (snowless) winters such as we sometimes get in the Niagara 
Peninsula, Quince A is successful for long periods only below the 
escarpment in zone 7a. The historic lows 
range from 16 degrees below zero F (-26.7 C) at Vineland Station to 
minus 12 F (-24.4 C) at Niagara-on-the-Lake at the mouth of the
Niagara River on Lake Ontario.

Sweet cherry on mazzard is successful here in 7a.

On Mon, 15 Jan 2007, derry and bill wrote:

> Is there anyone in the East, or even eastern WA, or Bernie Nikolai in
> Edmonton, who can tell me how cold they think it gets in the soil when
> the above ground temps are -30°C or -40°C (colder than -20°F). My
> conversion ruler doesn't go below -20°F!
>
> I have (above ground)pots of M9 and M26 apple whips and the above ground
> temperature has reached -12°C (+10°F). They are out of the wind in my
> carport. There is no snow cover in my carport.
>
> Should I be concerned?
>
> I also have St Julian A plum whips and Mazzard cherry whips outside with
> snow cover and the overnight low temperature has reached -12°C. Any ideas?
>
> There is nothing much I can do now and the weather is reported to be
> warming, but I'm interested to hear what growers who have more
> experience with cold temps have to say
>
> Derry
> south coastal B.C.