I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
The growth habit of a Japanese maple tree is due in part to the growing conditions and any training/pruning you do. Most will form a dogwood like form quite naturally. The ultimate size of a Japanese maple can be determined by tying the variety name and "Japanese Maple" into the search box on Google.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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