Bigleaf maple occurs in the Pacific Coast region from just south of the
Alaska Panhandle in British Columbia south through the western portions
of Washington and Oregon to southern California. It is generally
restricted to the west side of the Sierra Nevada-Cascade crest.
Bigleaf maple's northern distribution is apparently restricted by cold
temperatures. Its southern and interior distribution seems restricted
by insufficient moisture and humidity At the southern end of
its range, bigleaf maple is usually restricted to canyons or riparian
habitats

Interesting question. I have generally considered this page to be a reliable reference documenting the native ranges of a number of tree species; the only problem is I'm not sure how to navigate these pages without searching for them individually through google.

Interestingly, bigleaf maple is native to a few locales east of the Cascade crest including just west of Goldendale, in the Pehastin Creek canyon south of Leavenworth, and in the Entiat River Valley. Collections from these areas ought to result in very cold hardy plants, USDA zone 5 at least, maybe 4. Thus, it is probably not restricted by cold winter temperatures at the north end of its range, but by competition from other trees that are better adapted to the year-round heavy rains.

Much colder Zone 4 climate comes across Washington way up in northeast corner, not sure nativity to central Washington equates to Minnesota hardiness.

"It prefers a climate with dry summers. In Europe, vigorously growing shoots tend to suffer in winter because they do not harden early enough" --MAPLES FOR GARDENS (Timber Press)

OK, I was looking at WA USDA map later and it was 5a I was thinking of that goes across the NE corner. They do have an arm of 5b dropping down into central WA, too, which must be what you are talking about.

Ron, I'm sorry your obsession with the faulty 1990 USDA zone map seems to impede your ability to make educated guesses about plant performance based on more specific climatic data available from the Western Regional Climate Center and other sources. Let's start with Leavenworth's all time low: -36F. Then consider that these maples occur at much higher altitudes (another factor that cannot possibly be considered by the map, since all the weather stations in that area are in the valleys), up to at least 4,000', so they can probably live through colder temperatures than what Leavenworth experiences. And then let's not forget that some plants have more vestigal cold hardiness than they need to survive where they are native, from a time when our climate was much colder. Considering all those factors together, I think it's a safe bet that bigleaf maples from central Washington can survive most, if not all winters in zone 5, and may be growable in parts of zone 4 as well.

Obsession, eh? Whatever, man!

*YAWN*

Aren't young people great?

Dear God, The Hardyness zones are the least of our chill factor worries. It is nice that some one is trying to help, and answer the question. Id rather some one "Obsess" a little, than never get my question answered. as well, Id think that sincere effort would comand some respect in itself. If I even knew half the places to look that BBoy does, Id not be lurking here.

What I started to say, is that micro climates have a lot to do with it when some things appear to be hardy in an area or not. Im sure we have all expierenced the thing where bad weather hits, and that one cool plant you just had to try makes it. Suprise!!!! or conversely, your friend accross town who bought one at the same time as you calls to say hers didnt make it. Some things are pretty set in stone, others could sneek by even ten years and 2 ice storms in just the right, miraculous little shelterd corner. on the other hand, some stuff that is suposed to do real well in my area cant seem to live coming through my garden gate. is it the little ravine I live in? the rocky river bottom soil? the cold sinking lower and heat rising? who knows? but the tiny individual climates even with in our own gardens do have a big effect on some things that are on the edge, or marginally hardy in a given area.

Sorry zzepherdogg, I'm not referring to this post alone, but to Ron's constant need to remind everyone what zone they are in, or what zone anything is in, without using any historical climate data to substantiate his statement. Other than that, I appreciate much of what he says. Yes, young people are great, if you're referring to me (do I dare assume this? I'm not sure... at this point there's a lot of serious plant people out there younger than me), thank you!

Hey Ian, Didnt mean to sound shrewish. I dont have any idea how old you are. I know that knowlege has not alot to do with age. I didnt mean to dis you. I can tell that you have a ton of intelligence in this area. As does BBOY. It hit a note with me because sometimes, if I have answered a question with perhaps not the most trendy or apparantly PC advice, people have jumped on it like I was sugesting rolling asphalt over the whole space and using silk flowers. I feel bad for the person attacked, because they were just trying to help, and I feel bad for the questioner, because it might make them feel wierd about this forum. Ive noticed that some forums are much worse than this one, and some are almost never like this. One I can think of, has kind and suportive remarks, even if the person is in disagreement. I have done this snappy response thing myself, and feel bad for it. trying not to any more, but again, its really the questioner who must find it off putting.