Oroblanco cuttings and general question on grafting for hardiness

[Pancrazio]

First question: is Oroblanco easily grwon from cuttings? Or does it have an hard time rooting?

I have been toying with the idea of growing a Oroblanco tree since a couple of year. My place is supposedly too cold for that citrus;  so i have to be prepared to have it under some serious cold stress.
From my point of view, i have got just two choices with that plant to deal with my cold winter:
1 - Get a cutting to root, and plant the resulting plant in the ground: this way even if the plant get freezed to the ground i can start over from a healthy root system, and in few years have the plant to bounce back to a fruiting plant. The downside of this method is that i don't get any advantage from a cold hardy rootstock, neither any type of stem protection that i could achieve with an high graft; once the temperature in the air layer close to the ground dips under the death level for the plant, the plant is gone.
2 - Practice an high graft on a poncirus plant. This way once the plant get too cold, is gone for good and I’ve got to graft again, but an high graft could help me on those cold nights and also defend the stem from cold pocket of air close to the ground.
In you experience what kind of strategy i should use to maximize the possibilities of my plant growing well and produce some fruits? What strategy is useful in cold plances?

[Ilya11]

I have been toying with the idea of growing a Oroblanco tree since a couple of year. My place is supposedly too cold for that citrus;  so i have to be prepared to have it under some serious cold stress.
From my point of view, i have got just two choices with that plant to deal with my cold winter:
1 - Get a cutting to root, and plant the resulting plant in the ground: this way even if the plant get freezed to the ground i can start over from a healthy root system, and in few years have the plant to bounce back to a fruiting plant. The downside of this method is that i don't get any advantage from a cold hardy rootstock, neither any type of stem protection that i could achieve with an high graft; once the temperature in the air layer close to the ground dips under the death level for the plant, the plant is gone.
2 - Practice an high graft on a poncirus plant. This way once the plant get too cold, is gone for good and I’ve got to graft again, but an high graft could help me on those cold nights and also defend the stem from cold pocket of air close to the ground.
In you experience what kind of strategy i should use to maximize the possibilities of my plant growing well and produce some fruits? What strategy is useful in cold plances?

I guess both methods are worth to try and compare, they have different advantages and flows.
Many depends on how often freezes killing stems of Oroblanco occurs. I am not a supporter of the high grafting, since I have seen  mutual influence of rootstock and graft with poncirus stem splitting.
Have you considered a third method: low grafting on poncirus and autumn soil banking for protection:


It is being used in many  regions occasionally experiencing stem killing frosts.
In case of freezing you still  have a lower part of the graft that will rapidly restore your plant. 

[Pancrazio]

To be perfectly honest i didn't even consider it.
I can't tell you why... must have been a subconscious thing. Maybe I’m slacking with works needed in the fall and i try to reduce the to the bare minimum? 
Jokes aside, this could potentially hold the advantage of both methods; my question is just one: how does this method perform when you got a day with maximum temperature under zero or you get snow?
Also, if the part above the soil line get killed, is possible for the necrotic tissue to "run down" the stem and kill everything above the graft? (I'm thinking about mold, to be more precise).

[Millet]

No method of protecting the trunks of citrus trees from cold is more efficacious than banking.  Never, in any of the worlds common citrus districts, has the temperature fallen low enough to injure the trunk of a tree through a mound of earth.  If the trees have been headed and grafted as low as they should have been, not only the trunk but a large part of the main scion can be protected with earth. The trees should be banked early before severe frost is likely to occur .  The earth should be heaped well up about the trunk of old trees, but young one should have a considerable portion left exposed.  If they are banked too high, respiration will be prevented and death of of the trunk and branches can follow.  The part most susceptible to the effects of cold is the point of union between stock and scion, which should be close to the ground, and the earth well banked about it.   After the trees have been banked, the earth usually settles somewhat, or is washed  down by the rain.  For this reason, it is usually best, three to four weeks afterward, to place more earth about the tree.  The banks are not likely to remain in good condition without attention from time to time. All grass and weeds should be cleaned away from the trees, and nothing but fresh clean soil should be used in banking.  If weeds and grass are placed in contact with the trunks, wood-lice frequently cause considerable damage. Banks should be removed as soon as danger of damage from cold is post. - Millet

[Pancrazio]

Millet,
thank you for your exhaustive and complete explanation.
Banking seems the way to go, then.
Only doubt remaining: once i remove the soil, in spring, i guess i need to protect the trunk from solar heat, right?