I wanted to bring up the Satsuma that I found growing in Wilmington, NC last year.
First, I know that it has been growing for at least 8 years without total die back. Some winter die off, yes. But, just some of the outer branches as you would expect.
Second, the Satsuma part of the tree is about 6 to 7 feet tall and 3 or 4 inches in diameter at the base.
Third, the trifoliate rootstock had grown to about twenty feet tall.
Forth, This Satsuma is from nursery stock.
In this area Satsuma trees have been killed to the ground or the rootstock at least twice in the last 8 years. The last time about 2 winters ago, it killed several other plants that had been living about 10 or more years. One was a Bay leaf tree that I’d had for at least 12 years.
But the Wilmington Satsuma didn’t die.
It could be a colder than normal very hardy Satsuma? If it were from a seed I’d think that possible. But, it was from grafting. This would give rise to the thought that there’s something about the grafting that makes it a very cold hardy Satsuma trees.
Now I’ve seen the results of high grafting on trifoliate rootstock. From my observation in Virginia Beach it makes the grafted wood more cold hardy than low to the ground grafting.
So my hypothesis is that the Wilmington Satsuma survived because the over grown trifoliate rootstock is pumping 3 or 4 times as much cold hardy sap as the Satsuma. This protected the Satsuma when others in the area died to the ground or the rootstock.
To test this theory I’m going to grow a few variations. I will use grafted Wilmington Satsuma bud wood.
One will be a control. A traditional low graft. Any emerging trifoliate buds will be removed.
2nd will be a low graft with a Nurse Branch of trifoliate rootstock. The Nurse Branch will be kept about the same size as the Satsuma.
3rd will be a low graft with a Nurse Branch of trifoliate rootstock. The Nurse Branch will be able to grow as big as it wants. This will simulate the original tree that I found.
4th will be a high graft. About 4 or 5 ft. above the ground. Any emerging trifoliate buds will be removed.
5th will be the original Wilmington Satsuma. After coming to this realization I drove over to see the “Tree” again. The owner had the Nurse Branch of trifoliate rootstock cut to 6 ft tall. Time will tell if this changes its cold hardiness.
I’m open to suggestions for #6 or more.
I’ll protect them the first year to give them a good start. Then I’ll monitor them each year.
In the close up pic the trifoliate is marked with a “T”. The Satsuma is marked with an “S”.
Terry

Hey Terry. How about some current photos of the tree.

I believe when you start caring for the satsuma it will be no more cold tolerant than any of the others. I have seen this several times where neglected satsuma survived the severe freezes. They were completely dormant with no sap in the trunk. The Kimbrought satsuma was in the nursery at Port Sulphur Louisana and survived the severe freeze of 1962 on it own root. After they were propagated they were no more cold tolerant than Owari.
The Vermillion1, Vermillion2 and Vermillion 3 were neglected trees that survived the same freeze. They were propagated on Trifoliata understock and were wiped out in the severe freeze of 1983. I saw the original trees back in the late 60s or early 70s.
There was an older gentleman at New Iberia Louisana that had all his tree budded about 4 feet from the ground. They had beautiful trunks but the freeze of 1983 wiped them out.

Cold hardy citrus offers a great challenge. For many of us in zones 7 & 8 it seems like a worthwhile undertaking. Although most of the cultivars are not palatable to a great deal of people some are worth the effort. Satsumas are noteably the tastiest of this group and any cultivar that exhibits extra cold tolerance should be investigated further. This "Wilmington Satsuma" might be one of those. Yes, I agree that any prolonged or severe freeze will wipe out satsumas. Fortunately those only come every 10 years or so. A good goal would be to find a particularly cold tolerant strain and/or graft in a particular fashion (maybe Terry's grafting variation trials can help us do this) that can enable the tree squeak by those 12, 13 or 14 degrees temps that frequent our zones. By doing so maybe you'll have at least a few years of good eating before it freezes out and you start over.

Terry writes in his above thread >>>"my hypothesis is that the Wilmington Satsuma survived because the over grown trifoliate rootstock is pumping 3 or 4 times as much cold hardy sap as the Satsuma. This protected the Satsuma when others in the area died to the ground or the rootstock."<<<

The trifoliate rootstock IS INFLUENCED by the cion top, in this case the Wilmington Satsuma, and the trifoliate stock is FOURCED to grow much more vigorously than might be expected. This is be due to the fact that here is one of the few examples of an EVERGREEN cion top grafted and growing on a DECIDUOUS root stock. There is no question but that food formation goes on over a much longer period in each year through the effect of the evergreen top. As an example, the diameter of grafted trifoliate trunks just below the point of union greatly exceeds that of seedling trifoliate trees of the same age when mesured at the same distance from the ground. While it should be borne in mind that the place of union between the stock and the cion is the one point in the trunk of a citrus most sensitive to cold. Besides the trifoliate stock imparting to the cion some of its ability to withstand cold, it has a tendency to retard growth in the spring, thus heping with early spring freezes. - Millet

Well his is the new version of the Wilmington Satsuma. I will try to get better pic later.
I would get closer but there’s a Pit Bull tied close to the tree. The old fellow is sickly and I didn’t want to disturb him.
I ran into a friend named George at a nursery last weekend. Our conversation got around to Citrus and it turns out that he is a friend of the old fellow who has the Wilmington Satsuma. This is good because the old fellow that owns it wasn't impressed with me. I was just another person who pestered him about the tree.
George was the one who cut the Trifoliate down to about 5 feet it look like. I told him my thoughts and he said he would not cut it any more.
Anyway my friend George said he would get me some bud wood. I’ll try for getting me closer for pic also.
I realize that we have had some cold hardy citrus anomalies over the years. And it seems that when we try to take care of them in the usual way they are not special any more. So what I’m looking for is to see if we can duplicate what happened. Not just grafting it to Trifoliate and expect it to be super cold hardy.
If I can isolate what made the Wilmington Satsuma survive that’s enough for me. I only need a few degrees. I can live with a 20 ft Trifoliate if I can get a producing Satsuma as a bonus. Then can we use other cold hardy citrus in the same way? Could I have a 20 ft Trifoliate made into a JoeReal style tree with 20 or 30 different citrus grafted on. Yes I’m getting carried away. But it would open doors.
Terry

Terry and Others,

If you plan on having multi-grafts, I strongly recommend that you place several of the coldest known cultivar on the topmost portion of the canopy, with enough spread to cover the othes directly over them. The lower you go into the tree, you can graft the less cold hardy types. Then you will only need to cover the tree around the sides each winter.

I have several cold sensitive types on my 50-n-1 tree and they are lower in the canopy, and the whole tree not a single cold leaf damage, even with our late season arctic blast. Of course we are warmer than your place each winter.

Regards,

Joe