Thank you for the pictures. Those fruit on your little bush tree look good.

It would really help other members here if you would give a more precise location of where you live. (Like closest to what major city, Portland, Eugene, the oregon coast?)

Lucky you. I'm in zone 8a, Olympia, at least 2 hours (or more) north of you, and unfortunately I found that Sudachi seemed unable to permanently survive here, despite being given some light protection. (Even with a gallon water container right up against its base) It declined over time, then wasn't able to make it through the second winter, and by that time lacked enough vigor to resprout. On the other hand, I've planted several Yuzu outside, and some of them have managed to make it, and are surviving. (Though I think even Yuzu much prefers a more optimal protected spot up against a house wall here) So, from what I've personally observed, it does seem Yuzu is a tiny bit more cold tolerant, and more vigorous growing, and that is enough to make a big difference in this climate that's right on the edge. Changsha mandarin seems to be somewhere between the hardiness of the two for me, and I have one in a protected spot near the south side of the house that has been growing well, and is over 4 feet tall now. (Well actually, it almost seems that Changsha might be able to survive a tiny bit more cold without damage, but Yuzu has more vigor and can recover better from damage, whereas Changsha is not going to be able to recover as well, and needs a little more warmth before it will start pushing out growth)

From what I've seen, the Portland area seems better for trying to grow citrus than in Olympia. Though it apparently gets a little better when you go even a little further north, not too far away from the water of the Puget Sound, in Federal Way and Seattle.

I'm in the Cedar Hills neighborhood of Portland. Data I've seen suggests the banana belt of Portland, unsurprisingly, is the downtown core, adjacent to the Willamette river, followed by Lake Oswego. Cedar Hills is just west of the West Hills, about 250 feet in elevation.

Experienced gardeners here seem to blame exposure to the cold, dry, east winter winds out of the Columbia Gorge for plant failures, moreso than minimum temperature. I have yet to experience those winds, but all of my neighbors say it does happen here despite the West Hills being between us and the Gorge.

I've been muddling my Sudachi fruit in cocktails this December and they're quite nice.

I forgot to add that the plant pictured cruised through two Z8 winters, but they were both in my slightly colder former garden in Dallas Oregon. I had it growing in an inverted nursery pot with the bottom cut off so it could root into the ground, but when I moved the plant to my new garden, it had not. Tht first winter had a stretch of 16F, impressive top and root hardiness. This will be its first winter in Cedar Hills.

Per USDA hardiness 2023 map, in recent times, much of the Portland metro area has become zone 9a and this is mainly the low-elevation areas. Higher areas, such as Forest Park, Mount Tabor, and Cedar Hills remain in zone 8b. Downtown 9a is somewhat artificial because of the density of pavement and large, heated buildings. The Gorge east wind events may lower the daily average temperature, but they raise the daily low compared to calmer areas.