I am trying to find specific information on the minimum temperature bigleaf maple will survive. So far I have found lots of interesting stuff on the ecology and distribution of the species, but information on hardiness varies from zone 5 to 7. I live in southern Norway, and bigleaf maple is extremely rare here. I´ve seen a cople of healthy young trees along the coast, and I´m hoping to find seed from a northern source to try this magnificent maple myself.
The hardiest Bigleaf Maple stock should be found near the northeastern edge of its range, as at Pemberton and Seton Portage. In the Fraser Canyon, it is abundant at Boston Bar; northward, it occurs more sparsely up to about 10 km south of Lytton (along the railroad). USA specimens of similar hardiness may be found around Lake Chelan in Washington, and at the confluence of the Lochsa and Selway Rivers in central Idaho. -Tony
I've seen Acer macrophyllum grown on a creek bank survive down to -2°F. Supposedly the tree can live down to -10°F. Jim
In Norway there could also be the problem of the Northern European summer conditions. The van Gelderens (Maples for Gardens) say It prefers a climate with dry summers. In Europe, vigorously growing shoots tend to suffer in winter because they do not harden early enough. Zone 6 (Europe 7).
Apparently certain coastal areas of Norway are much warmer than the inland areas are. Even still, Oslo's climate is not that much cooler than Berlin's average temperatures are. I suggest you join this forum and tell us how cool you do get in Norway and I'll figure out a way for you to grow this tree. If you can keep it alive for 5 years in the ground you should be okay with it. Most sources consider this Maple a Zone 4 at a minimum but with Winter protection and other safeguards this Maple can handle Zone 2 temps. The point that the newest growth will not harden off is quite valid. I know that is true from the plants I've grown in a Zone 2. What people do not fully realize is the growth cycle of the tree in such a cool zone when the length of the growing season is more of an issue than the actual cold is. What happens to me with most of my Conifers is that I will get an initial spurt of growth in late Spring, which is May at that location and then the growth about a month later will gradually stop. Long periods of sustained temperatures without dramatic evening temperature reductions will initiate a second growth spurt, about the same thing that happens in most areas in mid-Central to upper Oregon. It is the second growth spurt that may not harden off in time for the onset of cold, not the first growth spurt but as the tree better acclimates itself over time it will know when to send out a second growth spurt and when not to. People have not paid attention to where we see this Maple grow naturally and what the surroundings are for this Maple. Grown in a Zone 6 out in the open with no Winter protection, yes indeed this Maple can suffer but we generally do not see this Maple in areas all by its lonesome. Even in a Zone 2 we will see the Maple growing on creek banks or in a dense thicket whereby the tree is generally protected from cold winds by some Conifers or lush growing large shrubs. Dry locations is a misnomer for this tree as most of the areas I've seen get ample rainfall with mid to late Summer rains becoming quite important for this tree. A sustained water source is probably the most important facet as to whether the tree will survive in the wild. Notice where we find these trees in cool climates, a primary water source for the root systems is not too far away from them. We can find this Maple growing in pockets in Alaska with an average length of growing season of 100 - 120 days. Oslo has a 190 day length of growing season which means if this Maple can handle Alaska's sustained cool weather that this Maple has a better chance of being grown in Oslo in that respect. The dilemma is how do we keep this tree alive long enough for the trees root system to grow and develop in order for it to adapt to its unnatural and new environmental and climatic conditions? We do it or better put we can help with knowing how to culturally aid this tree to make it better adapt to where we want to grow it. Can you grow a Big Leaf Maple in southern Norway? If you take enough precautions and with proper site preparation you have a decent shot at being able to grow it there but it may not be easy for you to do. It will be a challenge but your reward may outweigh the overall risk. Anyone can grow a tree that everyone else can grow but not everyone can grow a tree that others have failed at or have not ever bothered to try growing for themselves. Where we learn is by trying as opposed to our not ever knowing for sure could we have fulfilled our quest to grow a tree we like in an area where it is not natural for it to grow and prosper. Jim
Sometimes a species sold in Britain and/or Northern Europe is from one or a few introductions, assigning a single hardiness rating to an entire species can be based at least partly on this.
Thank you for some interesting comments. The climate of coastal Norway is similar to that of coastal BC, from around northern Vancouver Island and north. There is no "dry season" in summer. The climate of inland Norway (and BC) is complex and not as easy to compare. In the southern lowlands where I live, average temp. in July is +16 C and in January -7 C. Precipitation is around 700 mm (28 inches), and summers are relatively dry. In normal winters the temperature drops to -25 or -30, the record low is around -40 C. I dont expect bigleaf maple to survive this, so I plan to grow it on the southern coast where we have a cabin. Minimum temperature in that area is around -20 C, precipitation 1500 mm (60 inches). From the data I have found, the extreme winter lows in the inland areas of BC where bigleaf maple grows are -25 to -30C. However, these areas have much higher temperatures in summer than any place in norhtern Europe. Our cool summers will maybe limit the hardiness. On the other hand, many plants grow well under conditions different from those in their natural range. Where I live, species like norway maple, linden, ash and oak are at their northern limit of natural distribution, but still they are considered hardy much further north.
Likewise, native western North American native trees that die out naturally well to the south of here are cultivated in our area. In nature they have to endure a much longer span of winters to persist in a region. Many of our current landmark trees do not date back far enough to have been present for a really serious winter. For example, one of Washington's most impressive Sequoiadendron giganteum was planted in 1920. Other environmental factors can influence natural distribution of trees as well, such as summer climate, fire history, soil composition, and glaciation. Competition from other tree species also plays a role. This latter influence appears to be manifested in the local distribution of slow-growing, shade-intolerant Quercus garryana, which is quite scattered north of the Tacoma prairies, presumably because it can only grow where moisture conditions are too severe (wet or dry) for other trees to crowd it out. At Three Tree Point, near Seattle the three trees (oaks) grow only out near the extreme tip of the point, with a solid bank of Arbutus menziesii starting immediately inland from them and completely dominating the rest of the ridge.
Hi Frodo: Thank you for joining the UBC forums. I’ll get back to you later. In time I will need to know more of your soil type, water holding capacity and what kind of coastal setting you have. Protection from cold winds and help in keeping the roots from being frozen for too long a period of time will be our main, central issues to overcome. I will say this now that you will want to start off growing seedlings, not starting from seeds. I am feeling, if you can pull it off to grow your Maples in containers at home until they’ve developed a root system, then transplant them later to your coastal location. I would want to baby them at home and get them to acclimate to your cold and then move them to a little warmer location. That is similar to what I did. I transplanted my Big Leaf Maples to their location in a Zone 2. They were not there to start with. The seedlings were initially grown in a micro-climate in between a Zone 7 and a Zone 2 and then I brought them to a Zone 8 to grow them on to a 7 gallon root system sized plant then transplanted them where I wanted them. You will probably lose a few of these so you may want to double your original estimate of how many of these trees you want to have. That is how we worked things when we brought in plants that have not ever grown here or were not supposed to grow here at all. We tried to grow them on, fully expecting a 50% loss the first couple of years, until we learned how to overcome our over zealousness in learning how to grow them. Hi Ron: < Sometimes a species sold in Britain and/or Northern Europe is from one or a few introductions, assigning a single hardiness rating to an entire species can be based at least partly on this. > Precisely, I agree completely. Transplanted Maples can be a whole different growing issue than native Maples generally are in their natural settings. You saw right through the hidden point I was trying to make. Thank you for your valued input in these forums. Your last informative post is what I’ve been waiting for as I know little or nothing about growing plants, other than some Agronomic crops, in your state of Washington. Best regards, Jim
