The swingle citrumelo in zone 7 are impressive. They survived dips to 6F. They are used like any lemon. In this video they are grown beside prague and Thomasville. Look at that huge yield! I was shocked they came through the cold with flying colors. My tree does have trifoliate leaves demonstrating its genetics where that cold hardiness comes from. My tree came from Mckenzie farms. Most growers in zone 7 are using incadecent Christmas lights and bagging their trees for protection. Note the fruit on praque in the video are towards the bottom of the plant. That fruit on prague set closest to the ground where it was warmer. @KS_razerback that further adds to your theory that the cold temps impact pragues fruit set more than other cold hardy citrus Prague Citsuma hardy sweet citrus . The gentleman in the video did a great job growing these!
Do you happen to know if all these trees can naturally pollinate each other? Or perhaps some are self fertile but others need pollinators and that means they will be crosses and those seedlings could have tastier fruit and/or be more cold hardy without any special work at crossing them right now.
I have seen people raising citrus in greenhouses where there were no pollinators getting fruit with no problems. Don’t ask me how that works unless it’s the fans.
So I think that’s because they’re self fruitful, but it could be that ants are pollinating them, that’s very easy especially with self fertile trees, Thomasville and Prague are self fertile according to a simple search, but Citrumelo is self fruitful, and apparently would be seedless, so if the Citrumelos have seeds, they should be further crosses with the other citrus, unless they’re Citrumelo seedlings and they can pollinate each other, which would be less interesting, but probably also good and useful, hopefully it could yield an Improved tree too!
I checked the YouTube comments and apparently Prague sets fruit poorly alone, so the Prague is probably also fertilized by the Thomasville or the Citrumelos, so it’s seeds should be complex hybrids as well, and honestly, that’s probably the best for breeding, since most of us want oranges, not lemons, although I would really love kumquats!
I grafted a Dunstan Citrumelo at my family’s house in New York (zone 7a/7b), and it has survived at least 3 Winters with no damage, down to 0°F. It is being grown in partial sun. Quality and flavor vary based on the amount of heat and rain but in the best year it was surprisingly good if you’re okay with tart.
Other Citrumelos like Swingle and 5star have also proven themselves, and it seems like even if they do get damaged, they recover vigorously and return to fruiting.
I have several Hirado Buntan Pummelo x Trifoliate Orange seedlings. One of them seems exceptionally hardy and they are all very vigorous.
Whenever I’ve tried Swingle, I noticed it also has some orange-y or sour orange-like components. It’s quite a bit more complex than a lemon, but it can definitely be used in its place and make some great lemon pie. Don’t count on it for zest though.
That’s been one of the biggest challenges, is that all of the hardiest citrus hybrids have awful-tasting rinds. The Iva Swingle is better and has fruitier flavor but it is similarly limited.
.