Eithieus,

I can only speak from my own experience, and it may (quite probably) not be relevant to your own experience, given that I'm farther north with fewer heat units than you have in the Willamette Valley.  My formative early years were in the southern hemisphere and I love citrus fruit, most especially "tangerines".  Later, I spent 18 years in southern California where fresh citrus fruit was "a given".  Now, here, north of Longview, WA, we have far fewer cumulative heat units, so citrus of any sort are virtually non-existent unless one has a greenhouse.  ......

Before I waste too much of your time, might I mention that the hardiest rootstock which is used for grafting citrus fruits onto is Poncirus trifoliata.  That being said, among the various un-grafted, edible citrus is "the mandarin", known to some of us as the tangerine.  Supposedly, the mandarin is the "hardiest" of the citrus fruits (--with, preferably, the Poncirus trifoliata as a rootstock) which is hardy down to 28 degrees F.  ... This, of course, is not a good guideline, given that such a numerical figure is given as the "low" and yet (--it seems to me--) that the assumption is that the very next day, and subsequent days, will again be considerably above freezing temperatures.

If you want to successfully grow citrus fruits in the Willamette Valley, I can only suggest (--for the sake of success--) that you have the trees under greenhouse cover.  Even in southern Florida where so many of the citrus fruits are grown, there have been freezes that have destroyed the crops.

I can only wish you the very greatest of success.  Proper prior planning might help to prevent potential disappointment.  ..."Gawd, what I'd give for a freshly picked ripe tangerine straight from the tree!"

Reinettes.

Note that the name of the fruit is Meyer lemon, not Meyer's, that is a hand soap.

We had one week of winter (so far) this year PDX with +21 degrees twice. That would defoliate most citrus.

I wonder if defoliation affects the next bloom cycle.

You would be better off trying ciitrus in large pots on wheels for cold-weather storage in a 40-50 degree garage.

Then you have the luxury of wheeling it anywhere in the yard in the warm seasons, or into the shade during "heat domes".

I did get a fair amount of tangerine and calamondin fruit via potted plants some years ago.