Author Topic: kumquat seedlings cold hardyness  (Read 217 times)

incubator01

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kumquat seedlings cold hardyness
« on: April 07, 2021, 01:58:14 PM »
I have some very nicely growing kumquat seedlings (the standard kumquat, not meiwa or anything else peculiar).
I would like to know if anyone knows how different in cold hardiness they are compared to the grafted ones.
I will keep these in containers of course and place them in a greenhouse in the winter but if they're not as cold tolerant as their grafted comrades then I must place them in a warmer location.

Speaking of which, perhaps not related on this topic but if I have to keep these in a warmer location, I want to make a air humidifier by putting expanded clay grains in a terracotta dish, soak the grains in water except for the top layer and place my seedling container on top of that (so it won't get wet). The purpouse is that the wetness in these expanded clay grains would evaporate. Has this been done before and does it work or am I doing a fool's errand?

SoCal2warm

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Re: kumquat seedlings cold hardyness
« Reply #1 on: April 07, 2021, 03:24:28 PM »
Well, this is not specifically about kumquat, but I experimented with planting an Ichangquat (kumquat x Ichang papeda) seedling growing on its own roots, in the US Pacific Northwest, climate zone 8a. Probably about the same latitude as France and a comparable climate.
It has not done so well. Technically it is still alive, the stems are still green, but it did not manage to put out any new leaves last year, for the entire year.
I would expect this seedling has to be at least as hardy as kumquat. (I know growing seedlings from hybrids though can yield unpredictable results)

I also read about an attempt at growing a kumquat near Atlanta, Georgia (which is in the South of the US), climate zone 7b. Even though it was covered by frost cloth, it did not end up able to survive.
I think normally kumquat can grow in the US South down to zone 8a, but probably not in zone 8a in parts of the world further north.
I also read one person report that they had a kumquat surviving in Seattle (supposedly zone 8a) but in a very optimal location on a warm south-facing slope, and that is in the middle of a big city.

swincher

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Re: kumquat seedlings cold hardyness
« Reply #2 on: April 07, 2021, 06:22:53 PM »
I also read one person report that they had a kumquat surviving in Seattle (supposedly zone 8a) but in a very optimal location on a warm south-facing slope, and that is in the middle of a big city.

Seattle moved from 8a to 8b when USDA put out their 2012 growing zone map, but the heat units are the lowest of basically any 8b in the world, so citrus is tough. I've heard of people growing kumquats here but never seen them with my own eyes.

Galatians522

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Re: kumquat seedlings cold hardyness
« Reply #3 on: April 07, 2021, 09:52:41 PM »
I would expect grafted and seedling trees of the same size to be very similar in cold tollerence (unless the tree is grafted to a root stock that is imparting additional cold resistance). To my understanding, much of the increased cold tollerence in mature trees comes from their larger mass. A larger tree simply holds more heat and has thicker bark than a small one.

incubator01

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Re: kumquat seedlings cold hardyness
« Reply #4 on: April 08, 2021, 05:37:12 AM »
ok, I'll see how they survive but from the looks of it it wont' be that good.
As experiment I put one seedling in the full soil of my greenhouse, just for the fun of it (I had too many anyway) :)

SoCal2warm

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Re: kumquat seedlings cold hardyness
« Reply #5 on: April 08, 2021, 09:43:58 AM »
Seattle moved from 8a to 8b when USDA put out their 2012 growing zone map, but the heat units are the lowest of basically any 8b in the world, so citrus is tough.
Well, that may be true compared to the US Southeast, but that is a little bit of an exaggeration to say the world.

There are some islands between Vancouver Island and the city of Vancouver (the Gulf Islands in the Salish Sea) that have lower heat units.
Even Whidbey Island, just a little north of Seattle has notoriously low heat units, definitely worse than Seattle. People there complain they need cold frames to be able to grow many types of vegetables.
The west coast of Scotland has some very low heat units, in zone 9. There are some parts of Iceland on the peninsulas that are surrounded by sea that are zone 8a with heat units that are so low it is nearly impossible to even grow an apple tree out in the open.

I'm about an hour south of Seattle, and the summers here actually get as hot as they do in coastal southern California, it's just that the time period of that heat is much shorter, maybe only lasts for a month and a half, and it's a much shorter growing season for citrus, maybe only a little more than a third of the year with temperatures high enough that the citrus can put on any significant growth, and I would say nearly half the year with the citrus in a state of complete dormancy.


To my understanding, much of the increased cold tollerence in mature trees comes from their larger mass. A larger tree simply holds more heat and has thicker bark than a small one.
That is what I've seen here (or actually closer to the Portland area, to be more precise) on a large Yuzu tree that looked like a hedge. The outer layer of leaves were almost fried, but the inner ones looked like they had not been affected as much.

I would guess that the outer leaves help block the movement of air. And also the water content in the outer leaves might release some heat energy as they freeze, helping to protect the inner part of the canopy.

That is why, to try to mimic that protective process, I cover a few of my more vulnerable varieties with a paper bag covering and put bottles of water inside, up against the plant. As little protection as this actually provides, I think it provides at least some, maybe 2 or 3 degrees of temperature difference.

Wind actually does make a significant difference. Citrus will freeze much faster in wind than with no wind. Plants usually maintain a temperature that is just a little bit warmer than the air surrounding them.

Even on the coldest nights here, most of the night is only slightly below the freezing point, but then it just dips down for three or four hours, and it will not dip below 15 °F for more than about half an hour (really rough approximation just for example). So I think protection from wind can be crucial.
The leaves of hardy citrus are not going to literally freeze if the air temperature is only just a little bit below the freezing point.

I don't know if this is specifically true of kumquat, however.
« Last Edit: April 08, 2021, 10:15:24 AM by SoCal2warm »

swincher

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Re: kumquat seedlings cold hardyness
« Reply #6 on: April 08, 2021, 12:00:30 PM »
Seattle moved from 8a to 8b when USDA put out their 2012 growing zone map, but the heat units are the lowest of basically any 8b in the world, so citrus is tough.
Well, that may be true compared to the US Southeast, but that is a little bit of an exaggeration to say the world.

Yes, it was definitely an exaggeration! I didn't necessarily mean Seattle alone, more that the entire Salish Sea basin is zone 8 but heat zone 1-3:



Yes, Iceland/Scotland likely have us beat, so I'll amend that from "the lowest basically" to "among the lowest" 😄

Plantinyum

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Re: kumquat seedlings cold hardyness
« Reply #7 on: April 09, 2021, 03:28:26 AM »
I have tree  small kumquat seedlings along with a pomello seedling,  they are s single summer old, that overwintered successfully in my basement with very little light and low temps to the point the soil had froze one time , but general temps were around 2-3 c .

incubator01

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Re: kumquat seedlings cold hardyness
« Reply #8 on: April 09, 2021, 06:53:46 AM »
I have tree  small kumquat seedlings along with a pomello seedling,  they are s single summer old, that overwintered successfully in my basement with very little light and low temps to the point the soil had froze one time , but general temps were around 2-3 c .

I heard people putting them in a basement before, I assume the air is more humid there, unfortunately our basement has no window with direct light, as as dark as hell there (perfect to grow mushrooms though xD) so I don't know if they'd survive 3 months in total darkness.

brian

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Re: kumquat seedlings cold hardyness
« Reply #9 on: April 09, 2021, 10:14:37 AM »
I recall that others have successfully overwintered citrus in the dark in their basements.  I think the key is keeping the soil between 32F and 55F so the roots are not active, but also not frozen.

I don't think they need any watering if done this way.  Maybe a tiny bit to keep the soil from completely drying out.

poncirsguy

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Re: kumquat seedlings cold hardyness
« Reply #10 on: April 09, 2021, 12:26:03 PM »
I have 2 Fukushu seedling 6 years old  and 4 Meiw seedlings 4 hears old.  I am listening.

Plantinyum

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Re: kumquat seedlings cold hardyness
« Reply #11 on: April 09, 2021, 01:41:39 PM »
I recall that others have successfully overwintered citrus in the dark in their basements.  I think the key is keeping the soil between 32F and 55F so the roots are not active, but also not frozen.

I don't think they need any watering if done this way.  Maybe a tiny bit to keep the soil from completely drying out.
yes, all my citrus are in there and I have watered them two times with very small amount of water, its cold, and is not very bright there so they use very little amount. The kumcuats I havent watered whatsoever , their soil still has moisture from the last watering in the fall ...
I will be taking all my citrus plants and others in a few days and will give them all a nice shower and watering....

incubator01

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Re: kumquat seedlings cold hardyness
« Reply #12 on: April 09, 2021, 01:49:44 PM »
yes, all my citrus are in there and I have watered them two times with very small amount of water, its cold, and is not very bright there so they use very little amount. The kumcuats I havent watered whatsoever , their soil still has moisture from the last watering in the fall ...
I will be taking all my citrus plants and others in a few days and will give them all a nice shower and watering....

That's very interesting to know. I would think the soil would get some sort of fungus from the moisture if it stays wet that long but apparently not :)
Will definitely try this out next winter!

Plantinyum

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Re: kumquat seedlings cold hardyness
« Reply #13 on: April 09, 2021, 03:15:20 PM »
yes, all my citrus are in there and I have watered them two times with very small amount of water, its cold, and is not very bright there so they use very little amount. The kumcuats I havent watered whatsoever , their soil still has moisture from the last watering in the fall ...
I will be taking all my citrus plants and others in a few days and will give them all a nice shower and watering....

That's very interesting to know. I would think the soil would get some sort of fungus from the moisture if it stays wet that long but apparently not :)
Will definitely try this out next winter!
they may get a problem if the soil is wet, mine is just slightly moist at best, most of the time they stay on the drier  side , today I watered the two lemons since one of them was having its leaves drooping, it has done this before and after watering they perk back up. I have some loquat seedlings in the same conditions that have some leaf drying from the dryness of the soil , the ones with the moistest soil dont show any  problems.
Only possible casualties may be two strawberry guavas that seem to be in a slow dying process ,involved wilting and dying of off branches, I am curious about this since I have a third one which is alive and ok and even has a fruit that formed in the fall still holding on the plant ....
« Last Edit: April 09, 2021, 03:19:41 PM by Plantinyum »

SoCal2warm

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Re: kumquat seedlings cold hardyness
« Reply #14 on: April 09, 2021, 03:43:28 PM »
I heard people putting them in a basement before, I assume the air is more humid there, unfortunately our basement has no window with direct light, as as dark as hell there (perfect to grow mushrooms though xD) so I don't know if they'd survive 3 months in total darkness.
That's not important. Plants don't need light to overwinter in the garage, so long as the temperatures do not get warm enough for them to grow (typically if the temperatures do not get much above 45 °F or 7 °C for citrus)