New Hardy Citrus Varieties 2024

[Mulberry0126]

Hey everyone, I just wanted to share some of our breeding/selection work. Our goal has been to collect and grow out as many open-pollinated Poncirus hybrid seeds as possible, and graft the most vigorous and/or promising ones onto 1-2 year old rootstock to expedite their growth and maturity.
Our best performer so far has been a Clem-yuz 2-2 and trifoliate orange hybrid (tentatively named Tri-clem-yuz #1), which went from germinating this past Winter, to grafted and ~4 feet tall by Fall. It's very vigorous, with dark, attractive, and fragrant foliage (all similar to its Clem-yuz 2-2 parent), and shows some promise in terms of hardiness, although time will tell.
All of these plants are being grown in rows outdoors in a very windy, unprotected, and full sun location. They are surrounded by landscape fabric and all of them are grafted onto Rubidoux trifoliate orange. I will update their profiles on our website as we collect more data, and the plants mature.
In the meantime, I hope you find this interesting and please feel free to share your projects as well.
https://themulberries.org/

[Walt]

All very interesting.

[Skandiberg]

The first one is my favourite. Its hardiness should probably be okay, I hope its fruit will be mostly like Clemyuz fruit. That can be a great one. I am very curious to see what becomes of it.

[tedburn]

Very interesting project and good information.
Let s hope for good fruit with good frosthardiness 👍

[kumin]

Excellent, I expect the upcoming decades to be exciting for Cold Hardy Citrus enthusiasts.

[sheaper]

What do you believe your lowest temperature will be in the coming years?

[a_Vivaldi]

The Tri Clem Yuz might price to be very hardy if I had to take a wild guess. Most trifoliate hybrids are hardy to something between 0 F and 15 F depending on the variety, but they pretty much all have parents that are hardy only to twenty or the upper teens. This new one has Clem Yuz as a parent, and it's hardy to something around 10 F already. Combine that with trifoliate and the odds of getting something hardy to sub zero temperatures start getting decent. Not guaranteed, but possible.

Not being deciduous though will still be problematic for really pushing the hardiness. I'm not aware of any first gen trifoliate hybrids that are deciduous. Evergreen leaves can cause issues and extra stress on the plant in very cold weather, especially in dry, windy weather and if the soil freezes.

But regardless, this cross has the potential to be very, very hardy.

My 2˘ anyway. I'll be following the Mulberries YouTube channel for updates as time goes by.

[Mulberry0126]

What do you believe your lowest temperature will be in the coming years?

In the past few years this area hasn't seen below 17°F or so. However in 2018 there was a low of 4°F. This feels like it will be a colder Winter than last year so I'm not sure what we will see, but likely at least below 20°F. I actually hope it goes a little lower to test some of these varieties early.

[Mulberry0126]

The Tri Clem Yuz might price to be very hardy if I had to take a wild guess. Most trifoliate hybrids are hardy to something between 0 F and 15 F depending on the variety, but they pretty much all have parents that are hardy only to twenty or the upper teens. This new one has Clem Yuz as a parent, and it's hardy to something around 10 F already. Combine that with trifoliate and the odds of getting something hardy to sub zero temperatures start getting decent. Not guaranteed, but possible.

Not being deciduous though will still be problematic for really pushing the hardiness. I'm not aware of any first gen trifoliate hybrids that are deciduous. Evergreen leaves can cause issues and extra stress on the plant in very cold weather, especially in dry, windy weather and if the soil freezes.

But regardless, this cross has the potential to be very, very hardy.

My 2˘ anyway. I'll be following the Mulberries YouTube channel for updates as time goes by.

I agree, Tri-clem-yuz #1 has the most potential if it can survive. Tri-clem-yuz #2 probably won't taste good but so far it seems deciduous which is a good sign. They have good parents for flavor and hardiness so crossing my fingers #1 gets a good mix of both. The seeds originated from a Clem-yuz 2-2 fruit.
Thank you for your subscription!

[Mulberry0126]

Excellent, I expect the upcoming decades to be exciting for Cold Hardy Citrus enthusiasts.

Thank you everyone.
I agree with this, I've noticed many other people sharing my enthusiasm for selecting and breeding new varieties, and even looking to repeat the F2 Citrange Winter hardiness trials. On a large scale this could yield some very good results.

[Wahl]

Looking forward to see how they do. You are in zone 7 if I remember right? I got way colder here in the last 2 years here in zone 7. I would love to try these from you in years to come.

[Mulberry0126]

Looking forward to see how they do. You are in zone 7 if I remember right? I got way colder here in the last 2 years here in zone 7. I would love to try these from you in years to come.

Yes and no - this area had always been considered zone 7b but in recent time it was updates to zone 8a. The Winters are fairly mild most of the time, but once every 5-10 years it gets cold enough to kill plants that would have survived otherwise.
I would be happy to share these with you. I hope by the time they are fruiting I will have more information about their hardiness. Tai Tri 4N and Tri-clem-yuz #2 seem like the hardiest of the bunch at the moment.

[a_Vivaldi]

Yeah it's definitely now zone 8a out in your direction (much like over here we're now zone 8b even though the 1990 map put us in 7b). But NC is weird. Because of the Appalachians blocking some but not all cold fronts, and more importantly because of the gulf stream and the way that NC juts out into the Atlantic ocean compared to SC or GA, the typical winter is pretty mild. But with the latitude being pretty high (large parts of NC are north of Missouri's southern border, and parts of NC's zone 8 are north parts of zone 6 in Kansas and even parts of zone 5 in Colorado), big cold waves do sometimes plunge the temperatures way, way down. Despite seeing several "zone 9a" type winters recently, I have seen single digit temperatures multiple times in the last two decades, to say nothing of the below zero temps we had as recently as the 80s.

It's for sure a climate where you either have to grow only stuff that's hardy to Pennsylvania at least, or stuff that you're willing to replant every ten years or so.

[Mulberry0126]

Yeah it's definitely now zone 8a out in your direction (much like over here we're now zone 8b even though the 1990 map put us in 7b). But NC is weird. Because of the Appalachians blocking some but not all cold fronts, and more importantly because of the gulf stream and the way that NC juts out into the Atlantic ocean compared to SC or GA, the typical winter is pretty mild. But with the latitude being pretty high (large parts of NC are north of Missouri's southern border, and parts of NC's zone 8 are north parts of zone 6 in Kansas and even parts of zone 5 in Colorado), big cold waves do sometimes plunge the temperatures way, way down. Despite seeing several "zone 9a" type winters recently, I have seen single digit temperatures multiple times in the last two decades, to say nothing of the below zero temps we had as recently as the 80s.

It's for sure a climate where you either have to grow only stuff that's hardy to Pennsylvania at least, or stuff that you're willing to replant every ten years or so.

Very interesting, that's a good way to put it! Thank you. It is definitely a weird climate, haha.

[Wahl]

Yeah it's definitely now zone 8a out in your direction (much like over here we're now zone 8b even though the 1990 map put us in 7b). But NC is weird. Because of the Appalachians blocking some but not all cold fronts, and more importantly because of the gulf stream and the way that NC juts out into the Atlantic ocean compared to SC or GA, the typical winter is pretty mild. But with the latitude being pretty high (large parts of NC are north of Missouri's southern border, and parts of NC's zone 8 are north parts of zone 6 in Kansas and even parts of zone 5 in Colorado), big cold waves do sometimes plunge the temperatures way, way down. Despite seeing several "zone 9a" type winters recently, I have seen single digit temperatures multiple times in the last two decades, to say nothing of the below zero temps we had as recently as the 80s.

It's for sure a climate where you either have to grow only stuff that's hardy to Pennsylvania at least, or stuff that you're willing to replant every ten years or so.

That is the same way here in north AL but we almost also dip down in to the mid teens and got down to 0f the last 2 years.

[Peep]

@Mulberry0126

Just a thought, it could maybe be useful for you to create a general topic where you post your videos, so we can discuss and talk about anything related to them? I can comment on your youtube videos, and I do sometimes, but the comment section there is not a good way to have a conversation. I could contact you through email, but then people will miss out on discussions that they might also find interesting. And I think google doesn't direct people to YT comments, while it does direct people to this forum.

So for example, I was wondering if you have found and potentially tasted or own multiple cultivars of Taiwanica? Because there seems to be quite of variety. I own between two and four different cultivars. I'm not sure, because I think two might be the same, and another one I'm not sure if it's actually a Taiwanica or not. So I only have two that I'm sure about and they do have different leaf shapes. However I have not had any fruits yet, except immature ones.

But this question doesn't completely fit this topic, hence the idea for you to create a general one. 

[Mulberry0126]

@Mulberry0126

Just a thought, it could maybe be useful for you to create a general topic where you post your videos, so we can discuss and talk about anything related to them? I can comment on your youtube videos, and I do sometimes, but the comment section there is not a good way to have a conversation. I could contact you through email, but then people will miss out on discussions that they might also find interesting. And I think google doesn't direct people to YT comments, while it does direct people to this forum.

So for example, I was wondering if you have found and potentially tasted or own multiple cultivars of Taiwanica? Because there seems to be quite of variety. I own between two and four different cultivars. I'm not sure, because I think two might be the same, and another one I'm not sure if it's actually a Taiwanica or not. So I only have two that I'm sure about and they do have different leaf shapes. However I have not had any fruits yet, except immature ones.

But this question doesn't completely fit this topic, hence the idea for you to create a general one.

Not a bad idea, thank you for suggesting it! I did not know if my videos warranted their own topic, but perhaps they do. Especially the seedling trials with these new varieties and other hardy citrus-specific content.
I actually only have one Taiwanica cultivar, which I got from Stan McKenzie. I'm not sure of it's origin, but it makes a great lemonade! Rather large fruit too. This coming season I want to select for tetraploid Taiwanica seedlings since I noticed a few this year but did not save them for myself.

[Peep]

Not a bad idea, thank you for suggesting it! I did not know if my videos warranted their own topic, but perhaps they do. Especially the seedling trials with these new varieties and other hardy citrus-specific content.
I actually only have one Taiwanica cultivar, which I got from Stan McKenzie. I'm not sure of it's origin, but it makes a great lemonade! Rather large fruit too. This coming season I want to select for tetraploid Taiwanica seedlings since I noticed a few this year but did not save them for myself.

Maybe you could also use the topic for some general or small updates that don't need their own topic.

By any chance, could you post a picture of a Taiwanica leaf of yours? I'm curious if it's the one with extremely narrow leaves, or the more regular one, or something else

[Mulberry0126]

Sure thing, here they are! It has quite narrow leaves compared to other citrus. The Tetraploid versions has broader leaves.

[Mulberry0126]

Just a small update on the seedlings being trialed outdoors - The Sacaton and Swingle seedling(s) with the exception of Pseudo Yuzu are performing incredibly. Improved Swingle looks unphased and Improved Sacaton (previously OP Sacaton) has no damage, even on the tender growth at the top which is extremely impressive to me.
Pseudo Yuzu was damaged severely after 17 F and died completely to the graft after 15 F.

The Tai Tri seedlings and Lemandarin seedling are also performing very well, no signs of damage except the tip of the Lemandarin.

The Dimicelli seedling is performing pretty poorly. It looked unphased in the 20s F, but once temperatures dipped below 17 F it has shown tip die-back and portions of the bark have discolored and died. It seems cold tolerant but not in full sun/wind conditions. The side facing away from the sun and wind appears completely fine. I may stick a clone in the greenhouse instead.

I'm very impressed by the Tri-Clem-Yuz seedlings, which look the most unbothered. Tri-Clem-Yuz No. 1 is surprisingly resilient for how citrus-like it appears; it shows no damage or discoloration whatsoever. No. 2 has been dormant the entire time and shows no damage as well.

We are expecting snow today and temperatures may dip below 14 F next week so this will be another good test.
I am also testing Conestoga 058 and 067 from kumin. They both appear in excellent condition; 058 is exceptionally hardy for how citrus-like it appears. I think it will be a winner for climates like mine.

[Wahl]

I have 5" of snow on ground right now, it will be moving your way.