Above 38 I open to let them see the sun.
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Just for fun, here is a citrus tree growing north of Birmingham, AL. It does not get any winter protection.
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Citrus season is approaching! Anyone want Ichang lemon seeds? I’ll have some off and on for the next month or so. I only have these and Meyer lemons, so any potential cross pollination is probably ok. Great as a rootstock for something else too!
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Since a lot of citrus produces fruit over the winter season and citrus fruit isn’t very tolerant of frost at all, what is the benefit of cold hardy citrus? One will have to protect the fruit from freezing – 32F anyway to get any fruit.
I guess the cold hardy citrus that produces very early (before Frost) might be interesting.
Mature trees will take brief upper 20’s without any damage to the fruit.
Cold hardy Citrus refers to the pipe dream of crossing Trifoliate Poncitus with any other relation and develop a fruit to grow in temperate zones as cold as Zone 6.
This is a Trifoliate growing at my neighbor in Washington DC
This is the fruit from that tree 
What does that fruit taste like?
Don’t get me wrong the fruit is very redeemable. After picking if you let them sit on the counter for a week or two they will develop a bit of juiceable pulp. The flavor will mellow and 1 fruit as an addition to a pitcher of lemon aid will give you a flavor quite similar to Filipino Calamasi Orange Calamansi - Wikipedia
So crossing a Zone 5 Trifoliate with a Zone 9 is bound to get you a Zone 8 fruit right. No the cold hardness is lost in 1 or 2 generations and the Pine flavor never goes away. Lay sigh and whoo. Cold Hardy Citrus is a pipe dream a red mercury and anyone that tells you otherwise is a fool.
This is my Cold hardy Citrumelo I purchased from Logee’s 
As you can see from the photo that is clearly not doctored or anything and if of course using a person with normal size not very small hands. Citrumelo clearly displays its Trifoliate heritage and will absolutly grow in Zone 7
What do you mean the Kool-Aid is ready. Kool-Aid always gets a bad rep it was actualy Flavor-aid those cheep bastards.
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So none of these trees can handle the true Z5 down to -20F once in a while?
Tony
True Trifoliate can
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I’ve got a couple trifoliate in the ground here (in a warm pocket of Michigan) and this year I actually got 6 fruit from my largest poncirus. They are still hanging in the tree (though I should remove them in the next couple days).
Once these plants got larger than a foot I’ve had almost no dieback on them from winter temperatures…
Scott
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To clarify, I was referring to warm climate citrus I.e. limes, Washington navel, etc.
Most citrus is zone 9 and higher and will not grow in most of zones 5 to 8. There is the orange tree in Birmingham Alabama that is producing fruit. and there are a few varieties of citrus that can take temps down to the teens. Birmingham is definitely zone 7.
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Those thorns!
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indeed, I dont know if its true but its has been said Trifoliate Orange is used as a Hedge row around the NSA.
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Yeah at my parents home in 8b Louisiana I have grown many citrus for many years. Some of the satsuma cultivars can take to about 20F or so with little or no damage and 3+ year old wood to mid teens, and some of the kumquats can take mid teens and 3+yr wood even more. My Washington Navels and meyer lemon can take low 20s. All are grafted on trifolate. When i lived down there i used to drape a sheet over them with a heat lamp for weather in the teens and i think about 11F or so was my coldest temps. The only trees I ever lost totally to cold were key and persian lime and grapefruit, those are less hardy.
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In 7b North Carolina, we move our Key lime, Meyer lemon, and Ichang lemon in and out depending on the winter temps. We’ve had 8 key limes and 10 lemons on our 3 year old trees this year. The lemons are still ripening on the tree and they will probably do some ripening indoors.
In Raleigh, there’s a huge cold hardy citrus tree in Raulston Arboretum, I’ve never asked what the variety is, but it’s at least 15 feet tall and always covered in big lemons in the wintertime.
@PaulinKansas6b, is your Meyer lemon in the ground?
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Yes it is inground. I havent done anything to it in years. But the ground will get a lot colder in 7b than 8b so if you put in ground in 7b it may need more warmth than 8b needs.
Sour citrus can be harvested much earlier than sweet citrus. Citrangequats are juicy enough by August or September. So those are earlier, and I’ve never had to protect fruit until the low 20s. Even sweet oranges can handle 32 degrees easily. I have had ichangs with lemons in the past ignore 21 degrees with no leaf drop.
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@manfromyard, where are you located? I see you’re also in 7b, do you have Ichangs in the ground? Don’t the lemons get ruined in the 20 degree weather?
kdegs, the orange tree in Birmingham Alabama is routinely exposed to temps below 20 degrees. There is no reason to bring Ichang indoors until temps are below 20 and probably would be ok down to 12 degrees. This applies to larger trees. Seedlings might be injured though less likely with cold hardy varieties.
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There was a trifoliate tree growing here in southern west-central KY, in-ground, in an open courtyard on the campus of Hopkinsville Community College, across the street from my former office…probably planted around 1970, it fruited heavily for the 10 years or so that I knew of it until the Easter Big Freeze Disaster of 2007 killed it…but not the ‘lawn’ of closely mown seedlings growing underneath it.
I gave a couple of Flying Dragon seedlings to a coworker here several years back…they’re growing rampantly and fruiting prolifically in her backyard garden.
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