Cold hardy lemons

[SoCal2warm]

I can share my experiences of an Ichang lemon growing in the U.S. Pacific Northwest climate region, climate zone 8a.

It started off in a container outside.
One year, during a cold winter, the plant was severely damaged and suffered much die-back. It was much more damaged than two Bloomsweet grapefruit plants that were right next to it. So I thought this showed that Ichang lemon was not very freeze tolerant.
But then another year it went through a winter colder than the first, and the Ichang lemon seemed to survive through it well, while the two Bloomsweet grapefruit plants ended up being killed.
The plants growing in containers were not far from the house, and got only moderate sun exposure during the winter.

Then I put the Ichang lemon in the ground, in a very sheltered spot on the south-facing side of the house, up against a wall. It was not covered or otherwise protected in any way. It was a moderate winter, with mild temperatures most of the time, but three days of moderate freeze, outside temperatures probably going down to maybe around 13.5 to 14.5 °F ( -10 °C).
It seems to have survived well, and as of March 15, the leaves are not looking too unhealthy, looks like it will do well and grow a lot this year.

I can also point out I planted two small Ichang papeda plants in the ground, further away from the house, and both of them did not end up surviving. Declined a little bit after going through the first winter, and then were finally killed by the second winter, even though the second winter was not as cold as the first. Yuzu seems to grow faster and recover better than Ichang papeda here, but Yuzu can also show decline and be killed.
In this climate, it seems very important to plant in a protected spot, very close to a house, in an area that is not as open and will not get much wind blowing across.

[a_Vivaldi]

I'm similarly in 8a, though probably closer to 8b than SoCal2warm. And I'm 8a in the South, which is a whole lot of different from the PNW.

My ichang lemon was purchased as a seedling last year. It was about 10 inches tall and quite yellow from neglect at the nursery.

Planted in spring, it put on good growth, reaching 2 ½ feet by late fall. A really early hard frost defoliated the top leaves, and by the end of winter it was mostly defoliated. The winter was pretty mild but had a few solid freezes. The low was 17 F.

It's now flushing new growth, the first of my plants to do so. Nearly had a late frost this week which would've been trouble with it growing so early.

As an interesting comparison, the keraji seedling I also got grew faster, reaching an impressive 3 ft 4 inches, but was winter killed. It almost survived by the like of things, the stems showed signs of life until February. A somewhat larger changsha put on almost no growth, remained yellow through the whole year despite adequate fertilization, and died after the first frost. Not representative I suspect.

Anyway, here's my ichang lemon.

[caladri]

How old was the keraji seedling when killed?

[a_Vivaldi]

I had it for one year, but I bought it as a one gallon pot. I'm guessing it was about one year old, so it would have been two years old. Might have been two years old when I bought it, in which case it would have been three when it died.

[Lauta_hibrid]

Hello everyone, this topic was left a while ago but I'll tell you about my progress. This year I managed to get flowers from the Chinotto x lemon hybrids. This is the third hybrid with Chinotto that flowers in the fourth year. I talked about this in another post... it's a good variety and as mentioned before, it seems to resist -8°C... I didn't know that. The bad thing is that the fully mature Chinotto is sweet, but I don't know if it's a recessive characteristic. The Genoa x C. maxima lemon also bloomed on me. It's not giving me hermaphrodite flowers yet, only male ones, so I don't know if I'll see fruit, while my hybrid with Chinotto does seem to be able to form fruit.

Limón x C. Maxima : the photo of the already open flower compared lemon (top) and C.maxima (middle and half dehydrated) and the hybrid below.







 
And Chinotto x Genoa lemon:

[BorisR]

Lauta_hibrid, in your experience, what is the zygosity level of Chinotto seeds?

[Lauta_hibrid]

Lauta_hibrid, in your experience, what is the zygosity level of Chinotto seeds?

Hi Boris! I'm waiting for this year's seedlings to sprout so I can get some statistics so I can use numbers to figure out how many hybrids and how many with dwarfism. In general it seems that there are: 11 seedlings, 5 hybrids, 2 of which are dwarf. But I still need seeds to sprout. I saw this in my hybrids with P.T., which, being trifoliate, are easily revealed. I'll tell you about the rest later. The strange thing is that when I used the Chinotto pollen, I didn't find any dwarfs... but there were few crosses, I should do larger tests.

[Lauta_hibrid]

Here I bring you updates on my resistant lemon hybrids. It is a Genoa x Yuzu lemon. In my experiences, the Genoa lemon has more than 30% of zygotic seeds and I know the plants well when they are born, they give leaves without wings or articulated petiole (as seen in the last photo), or they also have some extensions along the petiole, as traits of their ancestor (the sour orange). These grew with well-formed winged petiole and one pigments well like other Yuzu hybrids, a dark brown color, different from the lemon. This is how I can differentiate the hybrids from the clone at the beginning. We will not know the resistance, but we can guess that it will be more resistant than the lemon.





lemon clone seedling

[Ilya11]

Winged petioles are quite unusual for lemon seedlings, but pigmented new growth is their characteristic pattern

[Till]

I have Limequat Tavares x Yuzu two seedlings. They are only 30cm high so far. Let's hope they will taste good. I have also Red Fingerlime x Ichang Papeda. The seedlings are only one year old but grow well so far. They look very similar to pure Fingerlime seedlings.

I find most theoretical considerations here quite reasonable. But perhaps we should just try. Thank you Lauta_hibrid that you took the first steps. Considerations about probabilities of success are good to remind us of the effort that might be needed but they remain highly speculative. A few years ago hardly anybody believed in the possibility of tasty Poncirus hybrids in the old citrus forum. Now we have already some and it has become silent about the skepticism. How much more can we hope in lemonlike hardy citrus?

Ichang Papeda is very sour but also bitter. When bitterness is not dominantly inherited (there seems to be hope) than a Lemon substitute is not far from possible on the basis of Ichang Papeda.

Opinions on Yuzu seem to greatly differ between Europeans and Americans. The reason may be that we Europeans have other types of Yuzu. My Yuzu allows you to make a very tasty lemonade. I do not view my Yuzu as a poor Lemon substitute but as a fruit the taste of which is perfect in itself that allows to make a lemonade that is equal to or better than Lemon lemonade. The only disadvantage is the many seeds.

My impression is that Pumelo is a good source for Lemon taste besides Lemons, as others have already noted. I think citrumelos should receive more focus in our brain storming. They have the poncirus taste that we don't want but also have a strong lemon taste.

I wonder why nobody wants to include Ilya's Ichangstars in his or her breeding plan. They are probably hardier than Swingle 5 Star and Ichang Papeda and have a better taste than both.

Has somebody tasted Citrumelo x Yuzu? There is such a cross in Frensh nurseries and is much praised for its taste. And Ilya has also produced such crosses. Perhaps a good Lemon substitute already exists.

Maybe I have overlooked something but I think nobody has spend a though to the taste of the peel. For me, Lemon peel tastes very good or at least interesting. A Lemon substitute should at best have an edible peel. It is alluring to think of Kumquat as a source for breeding now. But I have Buddhas Hand x Kumquat and can tell that its peel is extremly thin and a bit bitter. It seems to me that crosses between Kumquat and Citrus have always a thin peel. Somebody who wants to breed for thick edible peel should therefore better think of alternatives to Kumquat: simply citron, Haruka, Keraji mandarine (peppery peel!) or better citrumelos. The peel of Poncirus hybrids usually tastes horrible. But Staraji has peel that is ok and I have a hybrid that is falsely sold as "Rusk" by Oscar Tintori nursery that has a peel that tastes like citrus peel. So it seems possible that the horrible peel taste of Poncirus hybrids can be outbred. So breeding experiments with the goal of edible peel may include citrumelos. The thick peel of pumelos seems to be easily passed on to its offspring while there is hope that the taste improves.

As I mentioned elesewhere, hardiness is relative. It is not only important how may digits below freezing a plant can withstand but also how resistant it is to late frost in spring. To those fearing late frost I would recommend thinking about Yuzu. It is sometimes less susceptible to late frost than Poncirus and my Yuzu x Poncirus grows as late in spring as pure Yuzu.

Pure Poncirus has different tastes. Some varieties have mainly a Lemon taste while others also have stronger orange notes. Good Poncirus types are already hardy substitutes for Lemons as long as you are only interested in making lemonade from them. (Let the juice stand in a glas for some hours and throw away the bottom fraction.)

[mikkel]

Hello Till,

just some random comments from my side

I have Limequat Tavares x Yuzu two seedlings. They are only 30cm high so far. Let's hope they will taste good. I have also Red Fingerlime x Ichang Papeda. The seedlings are only one year old but grow well so far. They look very similar to pure Fingerlime seedlings.

I once had a Faustrime x I P seedling that looked like a Faustrime, but with a leaflet like I P.

Ichang Papeda is very sour but also bitter. When bitterness is not dominantly inherited (there seems to be hope) than a Lemon substitute is not far from possible on the basis of Ichang Papeda.

There is at least one I P which is not bitter, no, actually 2; IVIA is the better known, then a seedling here in Germany, in the Rhineland which is also seedless as long as it is not cross-pollinated.

Has somebody tasted Citrumelo x Yuzu? There is such a cross in Frensh nurseries and is much praised for its taste. And Ilya has also produced such crosses. Perhaps a good Lemon substitute already exists.

There are different ones, the one at Adavo, a hybrid from Zdenek Cernoch, is not so tasty. I didn't like it, but it is very hardy.

[bussone]

My impression is that Pumelo is a good source for Lemon taste besides Lemons, as others have already noted. I think citrumelos should receive more focus in our brain storming. They have the poncirus taste that we don't want but also have a strong lemon taste.

This may be another difference between the US and Europe -- the US doesn't have much in the way of pumelos and they are nearly absent from mainline grocery stores. (You might see one variety, seasonally, if you see it at all) I get the sense that Europe has more variety here.

As to an earlier point you made that I didn't quote, sometimes there is value in just growing 1000 seedlings like kumin did and seeing what survives and has value. It can even be worthwhile to regenerate old crosses, because we are looking for different traits than Riverside or the University of Florida were looking for.

[mikkel]

I get the sense that Europe has more variety here.

it just seems that way. Seen from Europe, it feels exactly the other way round   There are no specifically european varieties, especially not in commercial trade.  I would even say that all European varieties are actually from the US.
At least in the Riverside collection you can find everything that is available in Europe.

[Till]

Regarding Pumelos, I think of Pumelos because they have the typical citrus taste but not the orange / mandarine taste and are closer to lemons in that regard. Fingerlimes are also extremly sour but their taste is not so complex as Lemon taste.

We have in fact not many Pumelos in our stores in Germany. They only sell one variety with luck two, a red one and a white one. They are called Honey Pumelo which is, I think, a cross between grapefruit and pumelo with bitter segment walls but non-bitter juice sacks. The same with grapefruits. They only sell Star Ruby. You may find one other variety in Turkish shops. So the stores are really boring. But you can buy many other varieties as plants.
Regarding hardy stuff we got almost everything from the US but have meanwhile bred a number of varieties by ourselves. We envy what you have but sometimes we have things that you don't have. It is a pitty that plant exchange between Europe and US is close to impossible. It should, however, be possible to legally exchange pollen. I think we should use that much more in future.

Just an afterthoughts to my comments on possible breeding partners: Limes and Lemons have both the citron as their father. That makes Limequats interesting. While any kumquat hybrids that I know have a thin peel it is not clear to me what happens when you cross a Kumquat hybrid back to citrus. It might be that the peel is bigger then AND edible.

Is anybody aware of "Violetta Voss"? That is a lemonlike variety with medium hardiness (around -8°C). It is probably a cross between a citron and Ichang Papeda. It grows very well.

[mikkel]

It is a pitty that plant exchange between Europe and US is close to impossible. It should, however, be possible to legally exchange pollen. I think we should use that much more in future.

Unfortunately, this is also no longer legal.

I have a Violetta, which bears reliably even as a small plant, is undemanding and quite acceptable as a fruit. The seeds give many zygote seedlings.

I got some interesting fruiting Violetta seedlings from Bernhard Voss. One is almost a pomelo-like type. Large, almost huge fruits and also hardy in South Tyrol. The other is more like a grapefruit, but I can't say much about it yet.

[Till]

Interesting the seedlings of Violetta! I did not hear about them before.

Regarding pollen, hmm, it is of cause difficult for a citrus enthusiast to avoid any pollen contamination whatsoever when he wants to write a letter to the US....

[mikkel]

of course, it is simply common dirt of an untidy writer...

[Till]

At least we two can shamelessly exchange plants  Nice to hear that your Violetta is well. I remember the young plant.

[Till]

Has anybody experience with crosses between Lemon and Pumelo or Citron and Pumelo? There are some such crosses around. I saw them in the catalog of Agrumi Lenzi. But I have never seen or tasted one. I wonder if the peel is edible or not.