update on hardy citrus collection in PNW, April 2021

[SoCal2warm]

Ichang papeda


another Ichang papeda

This one came from a rooted cutting.

The leaves on both Ichang papeda plants have turned a very pale yellowish color.
They did this after the last winter too, but were later able to start putting out some new leaf growth at the start of June.

Dunstan citrumelo

Looks moderately okay. Leaves are still green but a little bit of a yellowish hue. The leaves will probably start to green up more later into the year.
I notice the trunk has gotten thicker than it was last year, so it is getting bigger.

Yuzu

This one is on rootstock.

Changsha mandarin

Leaves look a yellowish hue of green. This one is in a very protected location, so I'm surprised the leaves don't look more of a healthy color.

Keraji mandarin


Bloomsweet


Both the Keraji and Bloomsweet were covered with a paper grocery bag, with a one gallon water container up against them inside, just during the several coldest days of winter in mid February. They are also planted in an optimal location, not too far from the house, on the south-facing side.
You will notice the leaves on both look a surprising dark green color, a good sign because normally the leaves turn yellowish from the cold.

All pictures taken April 1, 2021
Olympia, WA, climate zone 8a

The plants are not too big, most of them I would say are around a foot and half tall, some more or less.

This might help give some of you a better idea of how these different varieties do in the Pacific Northwest climate.

[SoCal2warm]

Sudachi

This one is growing in the back up against a fence, far away from the house.


tiny little Keraji seedling in the ground, on its own roots

It is still alive, and has now gone through three winters so far, but has not grown too much. It's only a little over 2 inches high.
I am hoping maybe if it is able to put on a little more growth, it might be able to start growing faster. I do realize that trying to grow Keraji here on its own roots is probably very marginal. It was an experiment.

Ichang lemon, in a container on the deck

The leaves look a pale green color. This was left outside all winter.

This I believe is a "MIC", in a container

supposed to be a ((Temple orange/tangor x trifoliata) x Ichang papeda) x Minneola tangelo hybrid , although there is not much information about it
So far it does not seem to be proving very cold hardy. I had another one of these planted against the fence far away from the house and it was killed after an unusually cold winter 2 years ago.
The leaves look like a pale kind of yellowish shade of green. Those leaves are probably not going to be able to recover, although it will grow out new leaves.

I am hoping this might have potential for further breeding.

Ichangquat seedling, on its own roots

grew this from a seedling. This has been its second winter in the ground, unprotected.
I'm not sure it got the best luck of the draw when it came to cold hardy genetics. Most of seeds appeared to be zygotic. When it was originally first planted it looked very healthy and vigorous. Last year it wasn't able to grow a single new leaf. All those leaves that you see on the plant have been there for two years. I think the leaves may still technically be alive, but probably not very functional. The leaves look a very pale yellowish color. The thin little trunks of the plant still look green though, a moderately healthy color. It might manage to put out a little leaf growth later.

There's also another Ichangquat seedling (not pictured here) with leaves that look a great dark green color right now. I suspect that one might have been pollinated by citrumelo, however, so its hardiness might not be representative of Ichangquat.
Indeed, due to Ichangquat seeds being very zygotic, it could be the case that the seedlings would be expected to show a range of different cold tolerances.
(not a subject I want to get too much into here)

[tedburn]

very interesting Socal, thank you. Could you still tell us what have been the lowest temps and how long have been the time of consecutive frost days to get a better imagination of what the plants had to take - thanks Frank

[SoCal2warm]

This has been a cold winter, a relatively long winter too (although that's typical for this region), although this has been a relatively mild winter in terms of how far the temperature has dropped. I think it only went down to around 22 °F (-5 or -6 °C).

What it has felt like, this entire "winter" season has really been more like a cold spring (springtime season), with the exception of a week in the middle of February beginning the 11th or 12th. I mean one could find a few camellia and rhododendron bushes with some fresh flower blooms on them throughout the winter, except during that single time interval when there was snow. But that is not atypical for this area.

There were a few light frosts before then and after then, of course, but those temperatures were barely just below freezing. Certain types of plant species were able to continue putting out some flower blooms despite those frosts.
But it was still a cold winter in the sense that we did not have any warm spells, and the temperatures were pretty much constantly and consistently cold.

Two years ago it did get down to 12 °F (between -11 and -10 °C), again in the early half of February. The Dunstan citrumelo and Yuzu shown in the pictures were in the ground then and survived that. The Bloomsweet was in the ground too then but had a covering over it, although with a vented fabric top, although since it was covered with a deep layer of snow that probably insulated it when the coldest temperatures came. It suffered some fairly severe bark damage at the base of the trunk but was later able to recover, even though I wasn't sure it would. The Yuzu suffered some moderate bark damage at the base of its trunk too. That was the same time when the tiny Keraji seedling was killed down to a half inch above the ground, although as you can see in the most recent picture it was able to partially recover.

[tedburn]

Thank you SoCal, very interesting, so we had much more temperature differences and a week with 5 days frost night and day and temperatures down to 3 degree Fahrenheit ( - 16 degree Celsius) and every day 100% full sun which made it worse.
But as far as I see I only lost my Dunstan, all other Citrus survived with more or less damage and some as Morton and  HRS899 a or Ivia and Prague start to get new buds.
If I can reliably report for sure damages and recoveries in some weeks I will make a short report with comparisons and pictures.
best regards Frank

[SoCal2warm]

a small update:

The Sudachi is beginning to put out a flush of leaf growth, which is surprising because its older leaves right now look scant and not really the healthiest.

Surprisingly the little Ichangquat seedling that hasn't seemed to be doing that well, a few of its leaves are starting to green up and are still alive/functional. Those leaves have to be three years old by now. These few leaves look more green than they did last year, when the plant wasn't able to put out any leaf growth. And I think I am seeing the tiniest beginnings of little green bud growth.

I guess both of these plants appreciated the mild winter temperatures.

[SoCal2warm]

Ichang papeda, some of the leaves are slowly beginning to recover their green color.


Ichangquat seedling, some of the leaves are beginning to recover, which is surprising. The leaves looked so pale before. It still has not grown any new leaves.


Bloomsweet beginning to put out some solid new growth now, looks good


Keraji, on grafted rootstock, looks very good. Some sort of insects seem to have taken some bites out of some leaves.


pictures taken May 13, 2021

[SoCal2warm]

The Keraji now has flowers on it.


The blossoms smell like a mix of the flowers of Satsuma mandarin, combined with the blossoms of a mild sweet lemon, with a little bit of honeysuckle.
I am surprised there does seem to be a little bit of distinct lemon blossom smell to it.

June 5, 2021


The Bloomsweet has also very quickly grown out a big new branch with leaves.


In case anyone is curious, I have smelled the flowers of Bloomsweet before. It doesn't smell like grapefruit blossoms, but smells much more like the blossoms of sour orange, very beautifully and potently fragrant like a perfume ingredient, with a hint of bergamot and pomelo blossom.
I think there are things that can be learned from smelling and carefully observing the smell of the flowers. One can gain inferences about the genetics of ancestry, or even gain some idea of how the fruits may be likely to taste.

[SoCal2warm]

The two Ichang papeda plants have begun putting out new leaf growth


Here is the Bloomsweet. It is looking good, leaves are a very healthy green color and it has recently grown out a big new branch, which grew out very rapidly. In the background you can also see a Yuzu plant (also doing well, grafted on rootstock) and the edge of a special hardy Parfianka hardy pomegranate plant.


The Sudachi put out three little blossoms, and you can see what looks like the beginnings of a little fruit druplet on one of them.
overall the Sudachi looks a little ragged, like it is not growing the most vigorously or putting out the most growth, but the color of the leaves look reasonably healthy.


The Keraji (on grafted rootstock) has put out an abundance of blossoms, despite the plant not being that big, and it looks like it is doing very well.

The flowers right now I would say smell like orange blossoms mixed with Satsuma mandarin blossoms and regular mandarin blossoms.

The special Ichangquat seedling (which I suspect may be a hybrid with citrumelo) is also starting to put out a flush of new leaf growth.


pictures taken June 12, 2021

[SoCal2warm]

Here is a update picture of the Bloomsweet. It is growing and starting to reach some size and establish itself.




Here is the very tiny Keraji seedling that has survived in the ground for a few years without protection. It lost its leaves earlier in the year (perhaps due to slugs eating the leaves) but it has now regrown some new leaves. The leaves are small and not too big but look decently healthy. This thing is very small, about an inch, less than two inches high. I'm not sure if it will ever eventually be able to put in some size. It seems to suffer a setback after each winter, but then very late into the season, around late July, it starts to recover but then there is not much growing season time left in the year. It looks about the same now as it did the same time of year last year, and the year before that. But it is amazing such a tiny seedling is surviving and not declining.




Here is the bigger Keraji, more medium sized like something newly planted, that's grafted on rootstock.



It is doing well. It had tiny little fruit druplets begin to form but it looks like most of them dropped off.

pictures taken August 10, 2021

[Millet]

Nice pictures, thank for sharing.

[SoCal2warm]

Here's the latest update
October 3, 2021



sorry for the low resolution images, was trying to fit 4 images into one picture to help reduce data space

A - tiny keraji seedling
B - Ichang papeda
C - Sudachi
D - ichangquat seedling (regular seedling)

The coloration on the tiny keraji seedling looks green and a very healthy color. However, this seedling just overall does not seem to be putting on any growth. It was the exact same size this time last year. The winters seem to set it back and then it recovers, but it does not seem to be able to grow to a size bigger than it was before. Those little leaves are all new. (There are five leaves, two of them very tiny)

Most of the leaves on the Ichang papeda are still very light in coloration, yellowish-green. I would say more yellow than green though they are still obviously alive. It seems they were never able to green up much since the winter. If you look carefully, there are a small number of newer smaller leaves that are a little bit more green in color but even those leaves do not look a healthy green. There are two of these Ichang papeda plants right next to each other and the leaf coloration on both looks exactly the same. Perhaps this variety begins to put out its new leaf flush too early in the year, when it is still too cold, and so the newer leaves do not develop the most healthy greenish color. When the very small new leaves initially start growing, they are a dark reddish color. I have never observed this growing them inside. It probably is a natural response to growing outside, either to the ultraviolet light of the sun or the cold.

The color of the leaves on the Sudachi look just okay. Not really the healthiest deepest shade of green, but okay, still definitely green and not yellowish. This little plant has not been able to put on much growth. It is a slow grower.

I may be mistaken about this but the Ichangquat seedling has not been able to grow any new leaves. All of those little leaves you see on the seedling are all old, from 3 years ago, the leaves that did not fall off (most of them did). But amazingly those leaves look like a healthy deep green color. It seems obvious those leaves have been able to recover. I think this seedling has almost not been able to put on any new branch growth. Yet the recovery of the leaves and the fact they have fully recovered their color since turning very yellowish during the winter is a good sign.

(This is the normal Ichangquat seedling, not the other one that seems to be hardier that I suspect is a hybrid)

I would say that all four of these are managing to survive, but almost not putting on much growth. Very slow growing. It seems they are marginal growing in this 8a Pacific Northwest climate. None of them were protected or covered this winter.

Bear in mind these are not big plants.
I took some measurements. The tiny keraji seedling is only 2 inches (5 cm), the Ichang papeda is 14 inches high (35-36 cm), the Sudachi is just a little over 16 inches (41 cm) high, and the ichangquat is 13 inches (33 cm) high but very narrow, with only 3 leaves.


The bigger keraji plant (not shown in the 4 images in this post) has one small yellow fruit on it, which seems not to have been able to ripen in time. It is less than an inch in diameter. (I mean it is completely yellow in color, not the slightest hint of orange-yellow)
It is still a small plant, so maybe the fruits will be able to ripen in future years. It is 17 inches (a little over 43 cm) high right now.

[SoCal2warm]

Here's the latest update from Christmas morning, December 24, 2021

Bloomsweet grapefruit


Keraji mandarin


Changsha mandarin (that's an Escallonia bush in the background)


Although you can see some snow and ice, temperatures had not really gotten that cold at the time of these pictures. Ambient air temperatures had not actually gone below the freezing point yet. The leaf coloration still looks pretty good in all three pictures. I'd say the leaves on the Changsha look the best, but it is somewhat protected by being half engulfed by that big bush.

However, temperatures tonight (December 26) are expected to go down to 18 °F, and the temperatures are not expected to rise above freezing for the next 4 days, which is an unusual thing for this climate. (It more often stays just right above the freezing point) Apparently there is Arctic air coming from the interior of Canada. It's actually colder here right now than in Minneapolis or Buffalo (although of course that will not last too long).
I put some paper grocery bags over both the Bloomsweet and Keraji with containers of water under there as well. They are not too far from the house. Right now there's about 6 inches of snow on the ground.

[SoCal2warm]

Here are two pictures to give you some idea what the snow is like here.

Yuzu on grafted rootstock


Not citrus, but a (somewhat) rare Rhododendron yuefengensis


December 31, 2021

[SoCal2warm]

From what I am noticing, going by the appearance of the leaves right now, the covering with the plastic bag and gallon container of water under there really helped protect the plant from the cold. The Bloomsweet that was covered looks better right now than the Yuzu that was left uncovered. Even though the Bloomsweet was only very haphazardly covered. The plastic bag only covered the top of the plant, although I pushed a little bit of snow up against the bottom to help provide a little bit of additional insulation. There were still plenty of big gaps between the bag and the ground. The temperature only went down to 18 °F. The leaves on the Yuzu look a little bit "fried" and pale, while the leaves on the Bloomsweet (which is supposed to be less hardy than Yuzu) do not look too bad.

[SoCal2warm]

Some additional (low resolution) pictures, so you can see how some of these look in the winter.
Pictures taken January 15, 2022

Here is what the leaves on the Sudachi look like


Ichang papeda


I planted a rooted cutting of Changsha right next to a Yuzu seedling to see how they would do. They are right next to each other. Both are less than 10 cm tall, and they are planted not too far away from the house.

small Changsha (on own roots)


Yuzu seedling (on own roots)


There's another Changsha that's planted in a more protected spot that is bigger and has leaves that look just fine right now. (I believe that one is on grafted rootstock) Interestingly, the leaves on 2 of the other Yuzu bushes (on grafted rootstock) look fried, while another looks bad but the leaves look slightly less than totally burnt. It seems inexplicable, except maybe these Yuzu bushes were just more exposed, did not have the benefit of snow cover.

The leaves on the Bloomsweet are starting to show the effects of the earlier cold now, do not exactly look healthy, but they look like they will survive.

[SoCal2warm]

I can provide an update. Not good news. Almost none of the hardy citrus seemed to do well this winter. The temperature dipped down to 9 degrees F on New Years Eve, despite the temperature not dropping too low for the rest of the winter. (Although it did dip down to between 16 to 18 in the early morning of February 23 and 25)

The only one that was completely undamaged and looks great was the Changsha mandarin, but that was planted in a more protected location and surrounded by a big bush that probably helped insulate it.

Keraji, with a gallon container of water right next to it and covered with a paper bag, died down to the rootstock.
Why did it survive fine through last winter but was killed this winter? I do not know. Maybe it ran out of energy?

Bloomsweet, which also had a water container next to it and was haphazardly covered with a plastic bag through the worst part of the winter, suffered severe die back. One two little branches down towards the bottom are still alive and green. I am not sure if it will be able to recover.

The Dunstan citrumelo lost nearly all of its leaves, except some towards the very bottom near a branch that was weighed down against the ground by the weight of snow. Those leaves will survive. Most of the branches look green and fine, but there were just a few segments of branches that have turned grey and look like they were very damaged. Fortunately it is a vigorous grower and I am sure it will recover and survive.

Sudachi survived, but only because almost the entire little plant was bent down against the ground and so was burried under the snow and insulated under the winds. It does not look great and looks somewhat tattered but the leaves are still alive.

The two Ichang papeda plants seem to have been very much killed back. Only the base branch very close to the ground is still alive.

Three Yuzu plants, all on grafted rootstock, appear to have finally died. They survived through several winters before, so maybe they gradually ran out of energy and then were not able to recover? It is interesting.

One tiny little Yuzu seedling in the yard close against the ground survived, though it has no leaves.

Another Yuzu seedling, 3 feet tall, that is in another location that is in more of a developed area near the downtown has survived. It lost all its leaves but the branches are still all green and it looks like it will recover just fine. It is growing on its own roots.

The Ichangquat seedling (the one that I thought might be a complex hybrid and be more hardy) was killed down to 3 inches above the ground. The other Ichangquat seedling only has one narrow little branch that is surviving, seems like the other two were killed back, and even that one surviving branch was killed back to only less than 2 inches above the ground, no surviving leaves. I do not know if it will be able to recover.

That tiny little keraji seedling is still alive and has a tiny healthy colored green leaf, but it was completely buried under a layer of mulch and was very close to the ground.

[poncirsguy]

I transplanted a Fukushu kumquat tree outside from a 30 gallon container.





We dropped to 3F this year and average below 0-F 10nout of 30 years.  Those 10 years often have multiple night below 0-f

[Millet]

You have done well growing that tree.  It looks very healthy and balanced.

[Melenduwir]

I'm so sorry to hear about all the losses this year, especially the ichang papedas.  I'm making sure to keep all my citrus in pots, brought in as defense against my 6a winters.  Some of the very hardiest plants (C. trifoliata) may eventually go in the ground, but the plants I'm hoping to use to generate seeds will be pampered - it's their seeds that will face relatively harsh conditions.

We're currently in the middle of a cold snap that took nighttime temperatures from low 50s to mid-20s.  I only hope I brought them all inside in time.

SoCal2warm, have you considered pruning your plants into forms that resist cold?

[kumin]

  I'm making sure to keep all my citrus in pots, brought in as defense against my 6a winters.  Some of the very hardiest plants (C. trifoliata) may eventually go in the ground, but the plants I'm hoping to use to generate seeds will be pampered - it's their seeds that will face relatively harsh conditions.

We're currently in the middle of a cold snap that took nighttime temperatures from low 50s to mid-20s.  I only hope I brought them all inside in time.

Melenduwir, trifoliata may survive outdoors for you. I've seen it survive with some damage at -20 deg. F. Being located 140 miles Southeast of your area, I don't see subzero temperatures every Winter. In January 2019 our lowest temperature was -12 deg F. the lowest temp since then has been repeated +5 deg. F this Winter. Poncirus+, with reduced off flavors might work for you, especially in a micro climate.

[Melenduwir]

Oh yes, trifoliata is considered suitable well into Zone 5, although it's not reliably winter-hardy there.  If I had access to land, I would put my upcoming seedlings right into the ground.

I don't have much hope of creating hybrids capable of surviving outdoors, I'm mostly just hoping for hybrids that can be potted and left outdoors as early and late as possible without having to worry about an unexpected frost.  I could probably generate a trifoliata variety that could tolerate even colder temperatures if it wasn't for that pesky transposon screwing up their reproduction.

[kumin]

At present I have a few hybrids of high trifoliata content that survived 6b Winters in fair to good condition. It's disappointing to see them survive Winter, then show injury during the last Spring frosts. I have one selection that has a later bud-break and appears to escape late frost injury.

[Melenduwir]

With the way the climate is expected to become more unpredictable, surviving last-minute cold snaps is going to be a pretty crucial trait to have.  And that's not even considering freak occurrences like Houston freezing over.

It's part of why I want to eliminate nucellarity as a citrus trait - it prevents adaptation.  Since it seems to have resulted from a transposon landing next to a key gene, I don't know if it's truly possible to get rid of it permanently.

[pagnr]

It's part of why I want to eliminate nucellarity as a citrus trait - it prevents adaptation.

The genome is probably not as fixed as many think, there are other mechanisms such as recombination and repeats,
i.e. swapping segments of chromosomes, repeating copies of genes to increase traits. Moving genes around can change how and when they are expressed.
Nucellar polyembryonic Citrus can still throw quite a lot of variants, not all seem to be zygotic, only slightly variable. Some others are distinctly variable.
Other plant species also reproduce by this method. There may be some advantage in producing fairly uniform offspring.
One may be numbers alone, that are not limited by outcrossing events, i.e. pollination?
Highly variable outcrossed offspring will also include a lot of adaption failures.
If as you say, if the environmental conditions are becoming unpredictable, then increasing variation could be like rolling the dice on a moving chess board.
Clonal reproducing species may be better suited to moving into suitable niches, or spreading as climate zones move ??

This Australian plant Syzygium paniculatum is highly polyembryonic, now rare in the wild.
It has also produced quite a few horticultural variants.
It is also widely grown as a garden ornamental all over Australia in very different conditions to its natural coastal range.
Polyembryony doesn't seem to limit it to a narrow environmental window.
http://aff.org.au/wp-content/uploads/Wilson_Szygium_final.pdf

[Melenduwir]

What you've said is very true.  And there are a lot of domesticated plants (not just citrus) that reproduce in non-standard ways, especially with formerly non-self-pollinating crop plants adopting self-pollination as a strategy.

But in the long term, plants that don't prioritize crossing tend to be evolutionary dead-ends.

[SoCal2warm]

Everything I had outside was killed, with only three exceptions. The Yuzu bushes all died. Except for a tiny own-root Yuzu seedling that was very close to the ground, which doesn't even have any leaves but is trying to bud out some growth.
The Changsha mandarin survived and kept all its leaves, but it was planted in a more protected spot surrounded by bush growth from another plant (escallonia).
The Dunstan citrumelo survived and looks good now, though it lost nearly all of its leaves except for the branches very near to the ground. Even it experienced some die-back if a few smaller branches.
The last was a surprise, the Ichang lemon managed to recover and is sending out some good growth now, even though it was growing in a container. It suffered heavy damage. This Ichang lemon plant has not seemed to be very cold tolerant in previous years. Maybe it is inexplicable luck. The container was not too far away from the house. It survived while a Bloomsweet right next it died.

The other Yuzu plant which is located in the downtown area survived but lost all its leaves. The branches look a healthy green, with only a few grey damage areas on the branch farthest away from the trunk. It is now sending out leaf growth.

Both Ichang papeda plants appear to be dead.

July 1, 2022

[SoCal2warm]

Two small updates

One of the Yuzu bushes that I thought was killed seems to be sprouting a few tiny leaflets from its base, right above the graft line.

A seedling that I grew from US-852 citrandarin (poncirus x Changsha) seems to be sprouting up from the ground. I had presumed it was killed back to the ground by the winter, but it is possible my gardener carelessly wacked it down. It is planted in a shady colder part of the yard where hardy citrus has not seemed to do well.

It does appear that I see some green at the very base of one of the Ichang papeda plants, close to the ground. I don't know if it will be able to grow out.