Could I get a suggestion on what oaks to use for Bonsai? I was looking at a Northern Oak on line that has great fall colors but I really don't have a clue here and they don't grow wild here. Thanks for help, Peter
Quercus agrifolia (coast live oak) do great as bonsai. They tolerate root work, leaves reduce well, respond to pruning and develop quickly. I've seen them used as hedges near me. But, they won't tolerate freezes, they don't develop fall color, and they don't have stereotypical "oak" leaves. Oh, just noticed you're in northEAST Oregon. This may not be the oak for you.
I don't know much about the native oaks in the US, but English oak is widely used in Europe and I've seen a few here too (one was in the National
show in 2016 I believe). They seem to grow well for me in western NY - I have one in my nursery bed that I hope to harvest for bonsai use in a few years. You'd have
to start with a seedling though and grow it yourself if you have the time/space, or purchase an older tree from a nursery and work it down to size.
Fall color seems a rather drab yellow brown, not like some of the other oaks.
Cork oak and southern live oak aren't going to stand up to NE Oregon any better than Q agrifolia. All of these will need winter protection. I'm guessing it regularly freezes at the OP's location. For me the hardest trees to deal with are the ones that are not hardy in your zone, but are not good indoor tropicals either. Trying to get them through the winter can be a real pain.
Good oaks for bonsai that must be wintered indoors in your climate - Quercus suber the mediterranean cork oak. It will tolerate a light frost, but if the pot and roots freeze - it is toast. Leaves are evergreen and look a bit like European holly leaves.
Quercus agrifolia - coast live oak as noted above by Brian Bay 9. Again, no hard freeze. Leaves are evergreen and look like holly leaves.
These two will develop faster than Quercus virginiana. Q virginiana will have to winter indoors in your area also.
Oaks that would be fully winter hardy in your climate:
my favorite is the bur oak. Quercus macrocarpa - this oak has the most coarse, plated, fissured bark of any cold tolerant oak. On a young tree, with little or no ramification and grown in part shade leaves will be positively huge. But with branch development, more degrees of branching, and growing in sunrise to sunset full sun the leaves will reduce dramatically. Leaves might never get small enough for shohin size trees, (less than 8 inches tall) but should work well for medium to larger trees. Winter hardy to zone 3, no need for any winter protection - just set it on the ground.
White oak - Quercus alba - bark not as rough, leaves are smaller and reduce better, but still stay too large for small bonsai. Cold hardy to zone 4
Swamp white oak - I forget the species name - similar to the white oak, The fastest growing of the oaks that are hardy through out zone 4.
All oaks are slow growing. Most oaks are hard to find as partially trained pre-bonsai. They are not often available. The time you save spending a hundred or two bucks getting a trunk over 2 inches in diameter is worth it. It can take 25 years to go from a seedling or acorn to a 3 or 4 inch diameter tree.
I would consider using a faster growing tree to mimic the type of tree an oak would give you. For example a Chinese elm cultivar 'corticosa' or 'Sejiu' would grow fast, be winter hardy in your area (they survive outdoors into zone 6, with protection, probably zone 5) The bark won't show much cork until older than 10 years. Full sun helps develop corking. Also, when you slow growth by putting them in a bonsai pot, they will cork up quicker.
Buxus sempervirens - the northern European boxwood is hardy thru zone 4 and can be trained to look like an old oak tree. It is slow growing also (at least in my climate) but it is fully winter hardy. Somewhat rough bark. Not a bad choice and older pre-bonsai are occasionally available. Note, other species of Buxus are not as winter hardy as B. sempervirens, so be cautious, ask for scientific name if the tree you are considering is only labelled ''boxwood''. The 'Kingsville Box'' is not as cold hardy.
Quercus rubra - northern red oak, and any of the northern red oak-black oak group of species. All have bark that is relatively smooth until quite old. At best for bonsai the bark will have some vertical splitting, and plates, but it won't become fissured in our lifetimes.
So while not bad, and certainly fully winter hardy, I would skip the northern red and northern black oaks in favor of bur oak or other members of the white oak family.
They are all around you. To start with, Oregon white oak, Quercus garryana, second cousin to California's Valley Oak, Q. lobata, are terrific for bonsai, leaves reduce, vigorous growth, yellow fall color. They have typical lobed oak shaped leaves. If you want to go dwarf, there is Q. dumosa, scrub oak. Full size leaves are under an 1 1/2 and they reduce even more. Very slow growth, small internodes, but they are evergreen. Canyon Live Oak, Q. chrysolepis make terrific buttressed trunks even as shohin, evergreen. Coast Live Oak, Q. agrifolia are fine in your area as are all of these down to 15F (but they are a host to Sudden Oak Death syndrome SOD. I don't think this is a consideration for bonsai as long as you are not near the coast. There is also Cork Oak, terrific bark, leaves reduce, evergreen, also good to 15F. I have grown all of these and I am almost exactly the same climate as you. There are even more species native to the Northwest that would work, do a little reserach for some more dwarfs. I know there are a couple more dwarfs that grow in the Sierras. The only disappointing one is Black Oak, Q. kelloggii; it has wonderful fall bright orange yellow color, pink buds in spring, but the huge leaves do not reduce. Compared to Eastern Oaks, you are in Oak Heaven.
I have grown all the oaks I have mentioned above, including Cork Oak, outside without protection for almost 30 years, but 15F is the limit. Go under fifteen and the roots are toast on Cork Oak. This is from personal experience. I lost a whole crop about four years ago when it dropped just below 15F and I didn't have my overhead irrigation freeze protection on.
@Brent - Peter44 lives in the far northeastern Oregon, the ''High Plains'', he is in an area where it regularly gets well below zero every winter. He is in zone 5. He does have a spot where he protects some trees. I don't know how much space he has.
Yes Brent, thanks for chiming in here and Leo the same, Ok, I do have a place or two where I plan on protecting all my Maples I got from you Brent, and I could put the oaks there also. I'll just throw all that junk I never use anyway out on the ground. It does have controlled heat and that's where the maples are now. I would like to get an Oak with nice fall colors like Pin Oak or Northern Red Oak, but maybe there is a better suggestion?? I would also like one that is started maybe. We have no oaks that I have seen growing wild around here unless the squirrel got involved from a domestic tree. Help appreciated, Peter
I've got Quercus agrofolia, suber, lobata, garryana, wislizenii, douglasii, rober, ilex, faginea, canariensis. and polymorpha and they all do well as bonsai where I am in the Sierra foothills. (can you tell I love oaks) The pots freeze every winter with no ill effects but we seldom get below the upper - mid twenties. A bigger problem for me is keeping the roots cool in the summer.
Hi Paul H and thanks for the input. Do any of the ones you mentioned have good fall colors? Do you collect them or buy them? When you say you have trouble keeping roots cool, how hot does it have to be outside before you worry about that and what do you do to keep them cool if I can ask. Thanks, Peter
Hi, I have a couple of European oaks to throw into this discussion.
Portuguese Oak - Quercus faginea
Cool bark and one years growth 👍😁
Quercus rubra ( I think)
I know the leaves on the Portuguese oak will reduce, not so sure about the scarlet oak. Both have a few more years to get ready to try and grow branches