Expect to see more from this cross. It has never received any special care. @39thparallel.com check out this 3rd or 4th generation! It would make its grandma proud! The jujube is excessively loaded with fruit to the point it can barely stand on its own. At just 3 years old its made it through drought , heavy rains , the worse cold and heat in years. Out of the thousands of seeds and seedlings I finally developed one. This genetic anomaly is already the heaviest fruiting type I have ever seen.
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Do you know what the seed descended from? The wild sour one, honey jar, or coco?
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These are definitely partially sour jujube, but the other half that cross, I doubt even Mike @39thparallel knows. You are familiar with his own experimental jujube project he has growing.
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Yeah, I was wanting to experiment with the same thing of progressive cold hardening with jujubes too with testing them in western Nebraska out at my sistersā, so Mike gave me a bag of Li seeds that shouldāve been probably a cross with something else and have something at least with larger fruit size, and not a single one of those pits had a developed seed. Maybe this year see if I can buy/trade for some Coco (it was the best tasting one in my opinion) seed, or from you if you have an excess of seeds 
.
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Li almost never has viable seeds. I think I remember Katy saying she would occasionally find one, but it was very rare.
Coco is probably the name you are looking for. Sugar Cane also matched Coco, per genetic testing.
Did any of the seeds I sent you last year germinate?
Is this the first year that it has fruit? If not, how was it?
A lot of jujubes are heavy fruiting, especially those with some sour in their ancestry. Hereās a pic of Texas Tart, which really produces a lot of high brix fruit with the kick of a lemon.
Sometimes, Iāll even have a sweet jujube with packed branches, like this one of Black Sea:
I think the most important common factor is small fruit size. Iāve never seen a tree with large fruit size be anywhere near as packed. In fact, large fruit size tends to be much less precocious as well. It seems to take an extra year or two to even get any production from them.
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Would it ripen in Denmark? Im still searching for a variety that ripens in our cool summers
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Whatās the flavor like?
Iām also breeding my jujus, but Iāve only been at it for a year. Have you found any parental traits that are more or less likely to carry into the next generation?
Iād love to hear about anything youāve learned from this project!
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I live in southern Denmark (close to Germany) and it is hard to believe that there would exist a jujube variety that can survive and fruit here. I have tried several varieties without any success.
Actually it is hard to make them survive here (outdoor) and if they survive they will never fruit.
Of course Clarkās Jujube sounds exiting and I will definitely try growing it when I someday get my hands on it. It will be the ultimate test.
I think that some very early pawpaw and persimmon varieties will ripen here. Actually I have reasonable (outdoor) results with the persimmon variety āPrairie Dawnā (AKA Claypool H-55a) and I expect that āGeneva Redā is even earlier.
Quote from another thread: āand āGeneva redā is just of the chart by ripening almost a month ahead of the other early ones and being really sweet.ā
https://growingfruit.org/t/hybrid-persimmons-future-look-great/2601/1082?page=55
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It is the first year I noticed the fruit.
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Mike actually cracks the pod off of the seeds in most cases instead of allowing nature to take its course. Nature takes one extra year. There are observations I made I will wait to note yet because Iām not sure what Iām seeing yet.
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How cold do winters get there? I think you need to be prepared to be shocked. Many people tell me I canāt do things. My gift is not my own it comes from God and as such I give him the glory and give away the fruit varieties when Iām done. The first ones I will give seed to is @39thparallel @smsmith @steveb4 @tonyOmahaz5 @KS_razerback @JesseS @bobvance as the initial test group to drop it back to zone 3/4 hardinesss. I have nearly half a dozen Iām confident are zone 5b hardy. This is the top 3 hardiest. I will take those seeds and seeds like those @BobVance grows and plant those in zone 3 and zone 4 next time dropping them back another zone or 2 of hardiness until @smsmith @steveb4 @northwoodswis4 @northof53 can grow them outdoors. in this way we will try to get them to zone 2 or 3 hardiness first and then plant improved types from the increased hardiness strains.
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Yeah, they did pretty well and are still going.
I forgot about black sea, if I remember right it was genetically thornless? Would be a good one to grow a lot of seeds from if thatās the case.
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I tried a couple jujubes at my old place in 5a with 4b lows every few years in the early 2000s. None survived the first winter. I donāt recall the named variety I tried. The others were seedlings.
I just did a search and according to Google AI there are jujubes hardy to zone 3? I rather doubt that āfactā
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AI is wrong constantly. Not a reliable source of information
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If Black Sea is genetically thornless, maybe (Black Sea X sour jujube) and select for thornless-ness. You could develop a high vigor and thornless rootstock.
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I may send people wood, but Iāve never lived below 6B.
But, I donāt think hardiness zone is actually the problem in Denmark. A google search says they range from 7B to 9B. Though in a few decades, they may be closer to zone 4 or 5 if the AMOC current stalls due to melting fresh water in Greenland.
Maybe the issue is more the average temp or amount of sun. In Denmark, the mean annual temp is 47F (probably less in places, as I only got a single number for the country). From a jujube study (Prof Yao), areas with mean temps of 50F are generally considered suitable for jujube growth. That doesnāt mean that some variety wonāt work, but it is harder. For reference, my annual mean temp is 52-53F.
I asked google if Denmark gets similar sun and it said no, far less (1500-1800 vs 2500-2800 hours). Denmark does have a lot more hours of sun during the growing season, due to the high latitude, but the light level is much weaker due to the angle. If I was to guess, this would be the reason he may be having trouble.
My suggestion would be to try growing Bok Jo. It has a slightly different leaf structure than most other jujubes. They are larger and a bit thinner. I think that may be one of the reasons it is so productive for me.
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It is occasionally -20oC (-4oF) here at my location in Denmark but it is quite unusual. Theoretical I am in zone 7 but it should be regarded as zone 6b. The problem is lack of sun and heat. Of course I hope that there is a possibility of finding a jujube cultivar that can grow and fruit outdoor but I doubt.It seems to be more difficult than finding suitable pawpaw and persimmon cultivars.
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The big leaves of Bok Jo are maybe an interesting point in climates with less sun and heat but you describe it as a late mid-season cultivar in another thread. Ideally I should try an early cultivar with big leaves but it probably doesnāt exist.
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I donāt remember any other cultivars with very large leaves and high production. Iāve see a couple with somewhat large leaves, but neither were particularly productive.
Iād suggest trying:
Bok Jo
Xu Zhou (almost the same level of productiveness as Bok Jo)
Black Sea (aka Russia #2)- high productivity (though not as super-high as Bok Jo), earlier season, and highest quality fruit
Sugar Cane and Honey Jar could also be worth a look, as they are productive, fairly early season, and great quality.
Iād be happy to send you some Texas Tart or Hidden Gem (also tart, small, productive) pits. But I wouldnāt suggest just grafting it in Denmark. Even if it works, the fresh eating quality is much lower than the other ones I listed above. I like tart, but Texas Tart is like eating a lemon.
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