Buddingman has told me that there is no benefit to grafting more than 6 inches above ground. Clearly he is correct that "banking" is a much safer way to make sure your tree survives in an extreme cold spell, but I just found this online--from LSU( I will post this link on our link forum)-- the point about dwarfing is interesting:

"Poncirus trifoliate Rubidoux is clearly the best rootstock for Louisiana citrus. It is the most cold hardy of the commonly used citrus rootstocks, and has some resistance to foot rot and is more tolerant of saturated soils. A viewpoint among many researchers is that, within limits, the higher up the bud on the rootstock, the greater the influence of the rootstock. With the use of Trifoliata rootstock, this is interpreted as more cold hardiness. Budding too high on Trifoliata rootstock may result in moderate dwarfing."

Part of the dwarfing is the internode length. If not much of that dwarfing rootstock is used, then less dwarfing. It all depends upon what factors predominate your specific area. Although budding high could increase tolerance to cold, but by how much? If you are just in a marginally colder area, then budding high could work. But if you have severe cold, banking would offer better protection than budding high, so budding low to use banking is preferrable.

As Joe Real said above " it all depends upon what factors predominate your specific area." For example if the soil in your area is high pH, or if the area has a history of burrowing nematodes, or an incidence of exocortis viroid or blight then trifoliate orange would not be a good rootstock even if dwarfing and freeze hardness was desired. I find the idea of rootstock graft height giving greater stock inheritance interesting, and would like to look into this subject further, as I have never previously heard of this. However, I agree with Bonnie that a high graft would not be beneficial when it comes to protection from a freeze.

Opinions differ on this one. I would rather bank than bud high myself as well.

My comments are: years ago there were trees in New Iberia Louisiana that were budded at least 4 feet from ground level. some one had told the owner of these tree that they would be more cold tolerant if grafted high. The moral of the story is duning one of the severe freezes all the trees were lost.

Man, I'm in trouble...

Have 61 cultivars now on one tree, most of them budded at 8 to 10 ft high! And so most of my other trees. But they are not grafted directly on rootstocks but series of interstems now. So far, all have survived prolonged 20 deg F exposure during the arctic blast, but I cheated nature, which can't be done economically on commercial scale

But I salute the brave souls who are venturing into much more colder regions where freezing temps could wipe out crops! I believe that when there is unpredictabiity of freezing, grafting low is a good insurance for freezing risks as Bonnie has shown by experience.

I have a few that are grafted directly to rootstock that are 8-12 inches above ground, but they are also on rootstock sprouts and the primary tree is still grafted only a few inches above ground.

4 ft above ground is really high for a primary graft!

Speaking of banking, I have what I think is a very simple and easy way to prepare for cold.--- I have placed 2 bags of composted cow manure next to each of my trees. If we have freezing weather I can simply lay the 2 bags against the trunk (on their side) --it gives me about 8-10" of freeze protection coverage. In the spring, when freezes have past, I simply dump the bags around the tree. The black soil helps warm the ground and provides a slow release organic fertilizer to suplement the regular fertilizer. At $1.25 a bag it is cheap and easy.

Skeet, how low can it go there?
Your average minimum and your record minimum?

In the severe freeze of 1983 we lost about 70 trees bearing trees. A lot of the nursery stock was dug and covered with about 2 feet of pine bark grit. This was in Dec of 1983. The following spring the trees were uncovered and were in excellent shape tne nursery stock was sold in the spring of 1984. In Dec of 1989 we knew another hard freeze was on the way. I ordered a dump truck load of pine bark grit and banked all afternoon before the freeze arrived. The tops were lost but the trees recovered very nice. The following fall all the trees were above 6 feet in height. That fall I was the only one in the area that had budwood. The house and lot were sold in October 1993. There were 9 trees in the back yard and they are fairly lrage and producing an abundace of fruit. They were on Trifoliata root stock.

That's a very good proven strategy Bonnie!

Come to think of it, half the time the citruses are storing reserves in the roots. If you have scionwood protected in the trunk, even with the top canopy completely damaged, recovery should be a lot quicker than replanting, simply because you'd have lots of reserves in the ground. Any surviving wood is all it takes after the freeze, so anything that facilitate better protection using banking would work well, like budding low.

The 2 freezes Bonnie mentioned took us down to 10 F in 83 and 7 F in 89/90. Our normal low is typically in the 20s-- mid to upper 20s most winters and maybe 1 out of 10 in the teens and 1 in 10 with no freeze.

I remember one freeze in the 60s that got down to 14, but stayed below freezing for 3 days.