I'm wondering if I can make further use of a south-facing wall on a 12 foot wide, 8 foot tall block building (plus a wooden gable) that I've already got a cold frame built up against. It wouldn't need to be as flat as a true espalier, but in order to be compatible with the cold frame -- I may eventually build a green house, in which case I might be able to forfeit the cold frame, but for now the cold frame is much more important than playing with citrus -- the citrus tree would have to be pruned to a single trunk three feet tall before branching, and then the branches would have to be kept within about 18" of the wall so as not to cast significant shade on the plants in the cold frame below. Further complicating things, I'd have glass on the area that the trunk would be in from February-early May, so the trunk would have to be able to tolerate the extra daytime heat while the branches were still at regular spring temperatures. I'd be interested in something like an ichang lemon, an owari, a citrangequat, or a yuzu. I'm guessing the answer is probably not doable and more trouble than it's worth even if it is, but I thought I'd ask.

Eric have a look here : http://translate.google.com/translate?u=http%3A%2F%2Fwww.zitrusgarten.net%2Fhomepage%2Fcitrusspalier%2Fcitrusspalier.htm&sl=de&tl=en&hl=&ie=UTF-8

That's a great link. Thank you!