Its from two 3' thick old trees in front yard. I have messed around with tiny ones and a big collected one and I want to bring this down to an inch or so above notchNo, you won't. It will thwart you at every turn. You can do your thing, and it will do its thing. Mother Nature will kick your ass. Remember, you heard it first here.
Could cut to first node in spring and it'll have full feeders out in no time...semi sun.The trunks can be nice on them I have one with a 12" elephant foot base but not sure what my plans are for it. Hard cut too late possibly for cut to blend in
no he doesnt lol i have not scene any good examples of this species as far as getting the leaves or nodes to reduce. field maple is a better choice.You know, as soon as you say something can not be "bonsai-ed" you know sure as **** someone will post a magnificent example.
Actually I vaguely remember seeing a few images out of Europe of well done Norway maples, Acer platanoides. It has different "common names" in EU as it is native to all of the EU, not just Norway. If memory serves me right, the examples are all of fairly large trees as bonsai go. All were over a meter tall. Check Walter Pall's website, good chance he has one in his collection.
My suggestion would be move your "seedlings" to wide but shallow grow boxes. You want the boxes large enough to hold more than 5 gallons of media, but you want the depth to be less than 6 inches. Wide, flat nebari is what you need. You also need enough media to support a tree that is allowed to get to 10 or 15 feet tall, then cut back, then allow to get to 10 or 15 feet tall then cut back again. You need to develop a substantial trunk before you really begin the "bonsai techniques phase". Leaves and leaf petioles will reduce only some, maybe 50%, so the large size tree is needed to keep proportions correct. Walter Pall's "Hedge Pruning Techniques" will work to develop Acer platanoides. But go big, a hedge 3 or 4 feet in diameter might be your developmental goal until the trunk is large enough in diameter to begin to think about initial styling. For a 3 foot tall bonsai, a trunk over 6 inches in diameter is not unreasonable. This is the problem with platanoides, most beginners don't think about a large enough diameter trunk.
Notice you often have long internodes, then a segment with short internodes. Always cut back to eliminate long internodes. Keep branches that are mostly short internodes.
Their native range runs through zone 4. There should never be any issues with winter hardiness. If you loose one over winter it is likely because the tree was replanted or heavily pruned too late in the summer. New growth did not have time to harden off. Don't transplant after August 15, and no hard pruning after Aug 15, until first frost. After leaf drop pruning can be resumed. If you do prune or repot out of season provide winter protection.
I will admit I have not worked seriously with this species. I dabbled while I was a beginner, and stopped when I did not get good results. As @Forsoothe! said, it will frustrate you. But I will add that it can be done if you follow the European's lead, and go big.