I would opt for Calamondin.

don't think that one is hardy enough for me zone 7a against wall.

A Thomasville would be worth a try. Not sure about Ichang Lemon, I do not have any experience w/ them. You might also consider a Yuzu, but they aren't super juicy. Whatever you choose, some form of winter protection will probably be advisable for at least the first few years until the tree is established and may even be necessary long term it all depends on your local climate. Best of luck! and let us know how it turns out.

Thomasville citrangequat purchased from Stan McKenzie have grown in 6b. see link below

Here is a link that might be useful: http://forums.gardenweb.com/forums/load/citrus/msg0413465229079.html?10

mckenzie-farms of stan mckenzie click below

Here is a link that might be useful: http://mckenzie-farms.com/photo.htm

I agree, Mckenzie farms is a good place to look for hardy citrus. I still don't know that I would recommend planting a Thomasville outside w/o protection in a zone 6b or even 7a if you want it to be healthy and fruit reliably in less than 10 years. However, I'm not saying it can't be done... I'm sure it can (the thread poncirusguy links to above proves that), but rqhansen's Thomasville, at least early on, completely defoliated every winter:
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RE: Winter hardy citrus (Follow-Up #13)
posted by: rqhansen on 06.17.2008 at 12:56 pm in Citrus Forum
I have a Thomasville that I got from Stan McKenzie that is 3 years old now and growing quite well. WE have had 2 winters in a row with consistenly cold temperatures here in Louisville, KY. It has lost its leaves every year so far but springs back with now problem. This year it has reached 6 feet tall with only a bit of Tip die back and this was with no protection. Now it is up against a south wall and I am sure that helps too....
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If your goal is usable fruit in a reasonable period of time, I would recommend some sort of moderate protection (more than just burlap or a frost blanket) irrespective of which variety of citrus you choose. But, if you just want to experiment, I'm sure many people here would be quite interested to see how it does w/o any protection! There are at least a handful of other examples of Poncirus hybrids doing reasonably well outside w/o protection in zone 7a areas.

I recommend a Nippon Orangequat as an excellent lemon replacement.

I gave up on nippon orangequat as I never could find fruit despite a 14 month search. Nippon orangequat trees grow well on their roots and I wanted to plant them for rootstock for my meiwa tree. Poncirus trifoliata is virtually un-graftable unless you are an expert, so I gave up on mine.

Another tree is the Nameiwa kumquat. It to goes to colder temps than most any other citrus

The link below gives data on cold tolerance of the hardiest citrus trees for comparison. Nippon orangequat wins

Here is a link that might be useful: http://www.walterreeves.com/uploads/pdf/coldcitrus.pdf

How about a harvey lemon They go down to 10 F

Thank you all so much for the input, appreciate it.

I think I am more interested in knowing the specifics of the fruit traits.

I want to use as a lemon/lime/Seville sour orange substitute for the juice for salad dressings, drinks, seafood seasoning. I can definitely wrap it up in burlap and such even xmas lights for the first couple seasons or bring it indoors like the rest of my citrus the first couple winters. Eventually though I want to plant it in warm microclimate spot I have for it in zone7a.

I assume all these have fragrant blossoms typical of citrus which is also a requirement? I did get to speak with Mckenzie farms forgot to ask if these all have fragrant blossoms or if any stand out for blossom fragrance. I think Ichang may have the largest and most fragrant blossoms. But the others should have fragrant blossoms too?

So basically the most important thing to me to is: juice quantity, juice quality (no offtastes/bitterness/astringency or extremely little), and blossom fragrance.

Here are my notes based on sleuthing:

Yuzu- Only real problem is here is juice content is so small- sounds like a teaspoon per fruit due to both small fruit (think 4,5 cm diameter tangerines as standard size) and also very thick peel, lots of seed, and occasionally dry. I am confident the QUALITY of the sour juice is good--as it is a classic culinary juice. Aromatic, zesty juice. The rind is awesome on these, but I have no interest in rind. It sounds like per fruit it's almost a 1:6 ratio Yuzu juice to lime. Do I really want to be juicing 6 fruit every time I can just a lime or one of the below 2? Maybe if the juice is that awesome--which it could be.

Shangjuan/Ichang lemon- Large fruit with 1/2 cup sour juice! Very seedy, thick peel, but still gives 1/2 cup sour juice which is a lot. The quality is suspect--some say it can used as lemon, some say it is way too sour and caustic like straight up vinegar with no citrusy flavor/zest/aroma. So maybe juice quantity over quality on this one. Also I think I read it doesn't keep well?

Thomasville Citrangequat- seems like the best option and a compromise. A 4cm x6cm fruit rough standard size (close to size as Yuzu, but oblong shape) but is juicy, not insanely thick skin, not insanely seedy. Not sure how much juice it offers per fruit--but is described as juicy and I'm sure it is more juice at least than the Yuzu. The quality sounds good too and may be like the Seville sour orange with some orangey flavor in the sour juice.

My main concern with this one is if it's only juicy when RIPE--to my knowledge citrus gets juicier as it gets ripe. Most people suggest using underripe Thomasville as lemon substitute--are these relativey DRY sour wedges though? The descriptions of juicy are surely describing the truly ripe fruit which I will not count on getting in zone 7a nor do I desire. I want something that is juicy when it is sour (like a lemon/lime/Seville sour orange), not dry when it is sour because the sourness is due to underripeness (like an underripe standard sweet orange--those are a bit dry.).

So overall, I think thomasville wins for me, but a taste test would help since I'm nitpicking on the quality traits--I may try to taste test some in November. Also thomasville sounds like it's a half notch hardier than Ichang.

If anyone else has anymore info or thoughts that would be great.

Remaining questions-

Blossom fragrances?
How much juice can you get from a sour underripe thomasville?

Don't expect edibility with any poncirus hybrids unless you are a smoker with no taste buds left. I've tried them all. They range from horrible to "I think I'm going to die." I once thought there was a better thomasville, but not really. Harvey lemon to 10F, dream on baby! The duration of the freeze has more to do with it than the minimum temperature. 24 hours of below 20F kill them ALL. I found yuzu less hardy than satsuma. I pulled up my mature yuzu tree as I couldn't figure out what all the fuss was about on the fruit.

Here is a link that might be useful: mrtexas

"Poncirus trifoliata is virtually un-graftable unless you are an expert, so I gave up on mine."

I haven't found that to be the case. There are lots of important details to get right but budding or grafting citrus is no harder than any other fruit tree IMHO. Best thing to do is find someone successful(not easy) propagating citrus and quiz them in person until you can do it. I did that in 2000 and have budded thousands since them. The only problems I've had budding citrus since 2000 is budding kumquat on trifoliate. Chip budding works well however. I don't do cleft grafting of citrus since in my experience budding and bark grafting are much easier and more successful.

See the attached link for my budding tips.

Here is a link that might be useful: budding tips

By edibility do you mean fresh out of hand eating?

lemon, lime, seville sour orange most don't consider edible perhaps either by that definition but have great value in kitchen? think verjuice vs ripe table grape?

By edibility do you mean fresh out of hand eating?

lemon, lime, seville sour orange most don't consider edible perhaps either by that definition but have great value in kitchen? think verjuice vs ripe table grape?

PersianMD,
Looks like you have put a lot of thought into this. Regarding trees w/ Poncirus genes, MrTexas is more or less correct, they will likely never taste as good as commercial citrus. However, whether or not they are good enough for for you really depends on your personal taste preferences and expectations. I know some people (who are not smokers) that say Thomasvilles taste fine, and even eat them fresh. Others think they are more or less useless. I personally do not have any problems even with the taste of straight Poncirus trifoliata, but you have to be careful to get only the juice! The smell on the other hand... awful, kind of like a mix of citrus cleaner and turpentine. Also, the resin is tenacious.

I would say that Thomasville is a reasonable first choice, if you don't like the taste, then you can always graft something better tasting (but likely less hardy) on it.

Orangequat juice is like a slap in the face. You either like it or you do not. I love it in soda. It is great in beer. Strong citrus flavor and zesty.

Here is a link that might be useful: nippon orangequat

Try a Citrandarin if you can find one.

Thanks a lot for the rec--I checked out the video of the citrandarin harvest--it is awesome!!!

Vegetable juicer should make plenty of juice from any citrus fruit