Ox, you technically still have two seperate trees, so the lesser cold harder one would still freeze. You are not changing the genetics of the varieties, just where they get their water and nutrients from. Thanks.

ox, Interesting question. I can't respond from experience but from what I've read I think your answers are: 1)yes and 2)no.
1) In an article in the Southern Fruit Fellowship newsletter, Issue #5, 1989, A.J. Bullard in an article about Celeste and Brown Turkey stated: "I find Celeste the M.V.P. of figs and an excellent stock to graft less cold hardy varieties onto to make them hardier."
2) A comment from Condit in The Fig: "One reason why Celeste and Eastern Brown Turkey are so extensively planted in southeastern United States is that the trees become dormant early and withstand lower temperatures than do most other varieties."
Putting these together, an assumption could be made that Celeste would affect the dormancy of the grafted variety making it "hardier"???

Fignut:
That is a most interesting proposition. It seems logical that if the rootstock induces early dormancy it would improve the cold tolerance to some degree. The theory will bear testing someday.

Now, we all know that rootstocks influence mature tree size. Nurserymen everywhere use dwarfing rootstocks on fruit trees of all kinds. If we had the proper dwarfing rootstock we could create a patio fig that never got out of bounds.

Fignut, or Al, Dr Talpa, could you explain how two genetically different trees could be grafted to be better for cold-hardyness? I guess my genetics are rusty, but usually grafting is performed for the quality of root system, hardiness against insects, and so forth.

Ox, I guess my question is that even if it does induce dormancy earlier, it does not change the genetics of its cold hardyness. For instance I have a two trees:

1 celeste (cold hardy) and 1 paradiso (for arguments sake, not cold hardy)

The cold hard version may not induce dormancy until later, because it cold hardy, way beyond what the paradiso could take. I guess I am is because just because you have grafted, does not mean that the dormancy really make a difference because the cold tolerancy is genetic. All of stuff like photoperiod, when to do dormant, and such is in the genes, not the root stock.

Let me know if you guys can explain this.

I have attached Als posting here:

* Posted by tapla z5b-6a MI (My Page) on
Sun, Oct 14, 07 at 14:11

First, let's make a distinction between between repotting and potting up. Repotting includes root pruning and a complete or near complete change of soil in the root mass, while potting up is simply increasing the amount of soil surrounding the current root mass when you move it to a larger container. Potting up can be done at any stage of the growth cycle, while repots are best undertaken immediately before bud movement in the spring.

Plants begin preparations for dormancy at the summer solstice. Lengthening periods of darkness are the actual trigger, and when night length begins to become longer than day length, growth regulators (hormonal changes) cause the tree to change from the business of increasing visible biomass (making leaves and extending shoots) to the business of building layers of carbohydrate-rich cells in the permanent parts of the tree (trunk and lignified (woody) branches. In short, the tree begins to save energy instead of spending it to buy more leaves and branches. The tree is charging its batteries for the portion of the growth cycle that it will be leafless and unable to produce enough food to power metabolism (trees use energy even when in deepest dormancy).

As day length continues to diminish, groweth regulators signal the tree to begin to withdray anything useable from the leaves. Carbohydrates and anything that can supply energy to the tree are translocated to the perennial tree parts. Chlorophyl is withdrawn from the leaves and they turn yellow. As this occurs, photosynthesis and accompanying auxin (a hormone) production slows and stops. A steady flow of auxin across an abscission zone (where the leaf petiole attaches to the branch) is required to keep the leaf from forming an abscission layer and dropping. Since the flow stops, the leaf drops and the tree is in the beginning stages of dormancy.

As chilling temperatures enter the picture, water migrates out of cells into the space between cells. This effectively increases the concentration of solutes bound within cell walls and lowers the temperature at which the bound water will freeze - the tree makes its own anti-freeze, and now, the tree is in deep dormancy.
*****
Ficus c. is one of those trees thast can be grown in areas where they never see frost or dormancy, or areas that get quite cold, where they take advantage of the dormancy response to allow survival during freezing temperatures. Cold-hardiness is genetically determined and will vary by tree, but the genetic offspring of each tree will have exactly the same level of cold-hardiness as the parent tree (except as is affected by cultural conditions other than cold - drought, e.g.). That can never chance, even if the tree is exposed to increasing cold for 100 years.
******
A tree that grows and fruits well in the tropics will not survive or fruit well when planted out in zone 7. Here, something called 'provenance' as well as the preferred climatic conditions come into play. The opposite is also true. A tree that grows vigorously and fruits well in 7, will prefer a cold rest and would struggle or die in the tropics.

So, you can pot up now if you wish and there will be no ill consequences. Once your tree goes dormant, try to keep it cold (within the lower limits of what the tree will tolerate) and from growiong, as long as you can. Trees grown indoors, unless they are under excellent light (halide/HPS/intense fluorescent) will in almost every case be using more energy than they are producing and will be declining. The result is that by next fall, the tree will have grown less in biomass and fruited less abundantly than if it had been allowed to remain cold and quiescent after its dormancy - even in consideration of the longer, indoor growth period.

If it was possible, the IDEAL way to keep a potted tree over winter is to allow it to go dormant outdoors, naturally. Then, move it to a cold place where it passes through dormancy and enters quiescence. Keep it there until danger of frost has passed and then move it outdoors to complete the rest of it's growth cycle. I realize that we don't all have walk-in coolers to keep our plants in, but a cold garage or outbuilding is going to be much better for the plant than allowing it to grow indoors.

Al

Here is a link that might be useful: Dormancy starts when

Ox, theoretically the cold hardiness of a tender grafted branch is the same, it is independent of the rootstock hardiness. But it is in theory, I don't know how it is in fact. My climate is mild (no frost or isolated light frosts) and the figs don't die in winter, so I can't try it.

Grafting have been very little experimented in figs, in my opinion it still is a subject to discover. Nurseries don't use it, figs are easy and strong trees, grafting is a time consuming task and it is expensive for them.

My instincts agree with Ax's theory, but we all know that theory does not always hold in nature. Some experimentation might be called for with regard to cold hardiness. A. J. Bullard may be correct in his thinking.

Now, as to tree size we have a great deal of evidence from nursery practice with other fruit trees. I suspect that if we grafted a large-tree fig onto one of the small-tree rootstocks we would get a small tree.
Ox

I understand what you are saying, but hardiness isn't determined solely by the lowest temperature a plant is genetically programed to survive. For example, young fig trees are genetically identical to the cutting donor, but can be killed by temperatures that their parent (if older) easily survives. Other factors can outweigh the genetic cold limit and cause dieback or death at higher temperatures. If a fig leafs out early - no matter how much cold it can take while dormant - and is constantly damaged by frosts, it is not going to be considered "hardy". That bad timing might be the situation with Alma, which has conflicting references on hardiness.
I've seen hardy plants labelled "tender" when the grower insists on amending the soil to "help" the plant. It seems to go against most gardeners' grain to plant in poor soil, even if the plant requires it.
It doesn't seem strange to me that a rootstock might influence hardiness. Rootstocks can shorten the initial bearing time of grafted trees, increase production, and change plant size substantially - all things genetically programmed into the scion. So if a rootstock alters some factor that increases winter survival, it isn't changing the genetic programming of the graft.
As I said before, I can't speak from experience. But A.J. Bullard is a respected authority, growing a wide variety of plants, and sharing his experience within NAFEX and other fruit growing groups. I don't think he would have phrased it as a statement of fact if it were just something he considered a possibility.

Fignut:
I agree, and when I have time I will read a bit more on the subject. This is a worthwhile topic because so many of us live on the cold edge of fig survival zones.

It seems to me that it would be worth knowing which scion stocks respond most favorably, if there is a difference, to grafting on cold-hardy roots.
Ox

Just wondering if the type of soil can affect how a fig tree can handle the cold better? Or what you can add to the soil to increase its hardness, from what I read it's not the cold, but the drying out of the bark from the cold wind that kills them. Is there a spray that could be used on the bark, when it's time to bring them in, and still leave them in the ground, with just some protection for the roots. We had -9 degrees two weeks ago here in CT.
Currently I have a 15 year black jack in a pot, a 5 year old Chicago Hardy in the ground, one 5 year old from Switzerland, (which I plan to put in the ground this year) and a one year old in a pot from the Republic of Macedonia (large fig type), which I was told it's extremely cold hardy. My Chicago Hardy will freeze down to the roots if I don't cover it, I found it does better if I tie it up and very slowly over a period of a week, bend it down to the ground, and place a huge plywood board over it, and weigh it down with heavy rocks, and cover it with insulation, and a tarp. It sucks growing figs in a ice box like I have here.
Gary