We started doing research into identifying, locating, and testing cold hardy figs, maybe 6 -8 years ago now.
The first thing that we noticed was that what the French consider to be cold hardy, is not cold hardy here, in our part of Connecticut.
From what I have been able to find on French cultivars of figs, is that the French consider cold hardy between plus10 degrees and down to maybe minus 4 degrees.
For Connecticut there are maybe a half dozen or so figs that might be considered cold hardy enough to plant out side without winter protection. Of course after they have become mature enough. Three to seven years is what most fig experts I have talked to consider mature.
It all depends on where your planting the fig. From what I can tell, most figs the French consider cold hardy, are only cold hardy through 6b. Even there it has to be planted in a protected spot.
If I remember right Connecticut has zones that run from 8, right next to the shore, to 5, were we are located.
Paul Tracesky tested Sal's EL about 30 miles north of us, back in the nineties. It was the only fig he kept from his collection of figs that he was testing for cold hardiness.
He told me that he felt that Sal's EL was even more cold hardy then Hardy Chicago. But, then there may be many more figs more cold hardy then Hardy Chicago. Even though Paul selected Sal's EL as the one fig to keep, after his testing, he still had it planted in a protected spot in his yard, and covered it in the winter with tarp.
The only figs we suggest to new growers in zone 5, for planting out side, with winter protection is Sal's EL. Which has become the gold standard for zone 5 locations in Connecticut.
But, Marseilles Black VS in my opinion is even more cold hardy then Sal's El, and a lot more cold Hardy then Hardy Chicago.
We have only been able to identify maybe three figs that might be cold Hardy enough to survive winters in our cold zone 5, part of Connecticut. They are Marseilles Black VS, Hanc's English Brown Turkey, and LaRadek's English Brown Turkey.
We are in the process of growing and testing those three. Marseilles Black is the only one that we have been testing long enough, to think it might be even more cold hardy then Sal's EL.
Growth of less then one year old Marseilles Black VS, withstood a low temperature of 5 degrees Fahrenheit last winter, without any winter protect. Except for some leaves we raked over it's root system. The top 12 inches or so of the little whip, was not covered with anything. So far Marseilles Black VS looks very promising, for zone 5 locations in Connecticut.
Also, there are many factors that will effect how a fig handles cold weather. Such as, whether or not it's planted in a dry or wet spot. Whether it gets enough sun during the summer. How much fruit it was allowed to bear the last summer. How much winter wind protection it gets. How does it handle FMV. Did it originate in a cold part of the world? How much fertilizer was it given during the summer. How much fig experience growing does the grower have?
I think until enough fig growers have been able to test the other new supposedly cold hardy figs, Marseilles Black VS will in my opinion become the new gold standard for growers who want to grow figs in zone 7 through zone 5.
The biggest advancement that we made in growing figs here in zone 5, was to stop thinking that a fig could be grown like the apples and pears we grow.
Hope that helps.
Bob - zone 5 Connecticut