Citrus tolerant of 0 degrees

All you have to do get the 3lb bag of sugar instead of the 1 pound. When you make the lemonade. Ha :lemon:


@evilpaul This is a neighbor’s tree growing in Washington DC. Survived several polar vortexes unharmed. it has to be 30+ years old. Trifoliate official hardiness is Zone 5

The flavonoid that interacts with medication is Bergamottin. largely found in bergamont orange the one used to flavor earl gray tea, but also in grapefruits and pomelos.


All Things Cold Hardy Citrus, news, thoughts and evaluations - General Fruit Growing - Growing Fruit

I personally like syrup made from the fruit. Diluted you get a juice simular to Yuzu or Calamansi


Bifoliate citrus anyone.

Citrus Pepeda, The other true citrus family. Korean and Japanese largely. One of the most popular hybrids of it is Citrus Hystrix, eg Markut/Thai lime, formerly Kaffir(derogatory) lime. And Yuzu.

Thais obviously didnt desire the cold hardyness of Pepeda’s but there many many tasty flavonoids.

ITs like when Citrus evolves cold hardyness it grows an extra leaf.
Ichang papeda x trifoliate orange - Oscar Tintori - Nurseries Worldwide - Citrus Plants


I have markut… :blush:

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@fruitnut … that 5 deg of protection he got was with 1 string of incandescent lights… he said he was going to double the lights…

I also know that since that video he has added 60 gal black pickle barrels in between his citrus and avacado… to soak up heat during the day and release it at night.

I have my lettuce hot bed (cold frame) where i can cover it with floating row cover… or even add extra covers on very cold nights. And have 2 strings of white incadescent christmas lights (300 small bulbs total) suspended over my lettuce crop. Just before Christmas it survived unharmed with low of 3F and 4 days below feeezing.

I think that most lettuce can survive mid 20s.
But i expect there would be some damage.

Mine had no damage at all.

It seems that my heat gain in the hot bed must have been 10-15 F ??

Not sure… but we are still eating fresh lettuce greens after a low of 3F and 4 days below freezing (mostly in the teens and low 20s).



Lettuce is very winter hardy for sure. @fruitnut has some great techniques as shown here Chilling my greenhouse

Turnips are also hardy.

Cloches were used many years ago when people needed to live off the land all the time. In my childhood i was blessed with no trash service in my area it taught me this when i was young. One day i was walking where a neighbor dumped garbage in their ditches and came across an old glass jar in the winter. Much to my surprise everything was green inside that jar. That was something to look at given it was snowing outside. Saw several more in that same dump with green grass in them. Didn’t take me long to think about bigger jars and vegetables. When i saw my first aquarium at a neibors property i watched those fish a long time realizing there was not much we couldn’t do. A few years later i saw my first green house.


@clarkinks … i will read thru that when i get some time… thanks.

I do not have a greenhouse and doubt i ever will.

I do like the idea of having a much nicer cold frame… and plan to work on that this next year and have it ready by fall.

One advantage to a cold frame seems to be… all it takes to get greens to survive our winters here is turning on a few Christmas lights a few nights each winter.

Well that and covering.

I can do that.

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Sounds like you have excellent lettuce. You dont really need a greenhouse. Your doing fantastic as it is in my opinion. If you want to have something fancier later you always can. Much of the time with turnips or lettuce we did nothing more than covered them with plastic.

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I have no doubt that there are citrus that can reliably live and fruit in zone 8a.
Despite the fact that most “cold hard” ones aren’t sweet, I’ve been looking for a truly hardy citrus for a long time, but hardy is a little daring, what’s cold to some isn’t so cold to others.

I have a small collection of “cold hardy” citrus and poncirus hybrids myself. time will tell how hard they are in the cold.
but from what I’ve found out, most hybrids are hardy to a maximum of -15-18C and have this unpleasant poncerin (turpentine/resin, don’t know how to describe it) taste

and that there have been so many attempts to breed a cold-hard citrus with poncirus, I thought of going other ways, such as breeding out the poncerin and related substances, so that at least one can do back crossings with poncirus. It’s not just sour, it’s resin/turpentine…like

if you can breed sugar beet from 1% “sugar” to 20%, you could also reduce the poncerin and increase any existing sweetness to 200%.
but i won’t die for this argument, it’s an idea,


Check out this accession in the USDA collection. It is believed to be a chimera between trifoliate and satsuma with the leaves being trifoliate and the fruit more like satsuma. No mention of hardiness, but is anyone growing this? I imagine if the fruit look more like satsuma then there’s a good chance the flavor is more like satsuma too since that’s the part of the chimera more dominantly expressing in the fruit.

Here’s a trifoliate clone called ‘Frost’ with low average seed count (3-10 per fruit). This would potentially be good breeding material.

Here is an un-named selection that produces monoembryonic seeds (most of the C. trifoliata produce polyembryonic seeds). Monoembryonic Citrus are good for breeding because their seeds do not simply produce clones of the mother tree.


I have Citsuma Prague. But there were solid arguments why it should be not more cold hardy, it is partiell poncirus and satsuma genetically, why should the satsuma genetic part be more cold hardy…
There was something that it makes more cold hardy, but I can‘t find the link to explain it reasonable.
Not all parts of genetic is equal less cold hardy, intimate metabolism… or something, and personal experience shows it is a bit more cold hardy…

But not a break through to cold hardiness

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I think 10-15 degrees is a good rule of thumb for plants protected with plenty of lights and a tucked-in fabric cover. In Dec I had an outdoor low of 7F for 2 days. The max/min thermometer underneath covering read 26F during that time.
My set-up had a polycarbonate top since I was afraid the weight of wet snow might rip off loquat leaves. The polycarbonate probably gave a few extra degrees.

Most Citrus are not sweet. Most of the sweetness genes come from Citrus reticulata and Mandarin Orange and Citrus Maxima Pomelo. But 30 years ago Lemons and Oranges were just as sweet as each other. Oranges are now typically twice as sweet as lemons. Its more the acid levels that render one sweet and the other sour to our preceptions. Lemons being 2-3 ph and oranges 3-4. Grapefruits have 12 calories per OZ and Oranges 14, but GF ph is 3.3.

But I digress. Sugar beets got sweeter not just from selective breading but from chromosome doubling. Citrus are notoriously resistant to chromosome doubling. Not only that they have a long juvenile period up to 20 years to fruit. At least working with Trifoliate is fun because those hybrids can flower in 3 years. You can select citrus for size, flesh and rind but turning on or off the biochemical factories seems to be difficult.


I think that is reasonable related to topic citrus tolerant 0 degrees…

It gives some important information to some 0 degrees „Citrus“ and the „character“ about that hybrids…

Check out this write up on ‘Dunstan’ citrumelo. I haven’t fruited mine yet, but I have three in ground which have overwintered well repeatedly in 8a with zero protection aside from good drainage.


Dunstan is one I want to get growing.


Interesting tasting video


In the video you can see that yuzu isn’t juicy. I first found out about yuzu while living in Korea. Over there they would make a preserve from chopped up yuzu mixed with sugar & honey (looks a lot like marmalade). Then you would just stir a spoonful of it into hot water. I loved it and will probably use mine this way if I ever manage to get a harvest. I think the low moisture content of the fruit helps to make the preserve more stable/less perishable.


If yuzu acts anything like Trifoliates. Then the amount of juice you can obtains grows several times after the fruit rests on the counter for a week.


I think yuzu is a good candidate for radiation treatment to reduce seeds like has happened with other citrus, especially since it’s used for juice. I wonder if it’s been tried, or why not

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