Oriental Maples ?
We all have quirks. One of my mine is that I use the collective descriptor Oriental maples. I do not use Japanese as a catchall for these maples because the attribution is often both inaccurate and potentially insulting. There are several Asian maples in use horticulturally but only some of them are native to Japan (e.g., Acer japonicum, A. palmatum, and A. shirashiwanum). What if the species is also found elsewhere, like the three just listed, or native in Korea, China or elsewhere, but not Japan? For example, A. griseum, or A. pseudosieboldianum, or . . .. I think the better approach, both more accurate and useful, is a more general descriptor. Before a sentimental traditionalist or one of my politically correct readers gets all bothered with use of the word oriental, allow me to explain. Oriental, as I employ it, simply means east (e.g., Platycladus {Thuja} orientalis) just as occidental (e.g., Thuja occidentalis) means west, although the common name for T. occidentalis is eastern white cedar (arborvitae). How's that for confusing? Perhaps an even better choice, more locational rather than directional, would be to call these maples Asian or Asiatic. Regardless, calling them Japanese is often inappropriate. It is all about perspective and, like so many words, oriental is a homograph. Oriental is a good word and I intend to keep it in my lexicon. BTW, one can differentiate between these two species of Thuja by checking the orientation of the foliage -- horizontal planes in T. occidentalis, vertical planes in T. orientalis. Uh-oh! Orientation, my word of the month for July 2022, has the same root. So, is it frowned upon, too ? :) But I digress.
I want to elaborate on several specific points concerning these maples, regardless of what we call them:
(1) ALL maples are woody and, like ALL woody species, maples exhibit indeterminate growth. For woody plants there is no stop growing (i.e., getting bigger) unless dormant or dead. Full grown (i.e., size mature) is a myth. A delusion most people seem happy to embrace. I could show you 'Bloodgood' (A. palmatum) specimens in Indianapolis 25+ feet tall with a trunk diameter of one foot, most of them planted too close to a building, walkway, or other woodies. Indeterminate ignorance.
(2) Maples have a shallow root system which makes them prone to develop roots exposed on the surface. The raised often pleated condition usually is the result of not having been planted at the correct depth relative to the root flare. The problem can be made worse by erosion or if the soil is compacted and clayey. Nature knows better, so when the problem occurs it is almost always anthropogenic. The shallow and often exposed roots also make it hard to grow plants under maples (including grass) but that does not stop the ignorant from trying. The aggressive maple roots will hog the available water and maples are well known for heavy shade production which exascerbates the difficulty.
(3) A common gardening omission mistake is not pruning one's Oriental / Asian maples. There are several reasons to prune your Oriental maples:
(a) the branches of most have a narrow divergence angle thus specimens benefit from corrective / avoidance cutting -- some species and cultivars moreso than others. For example, Acer palmatum 'Katsura' is a beautiful plant in spring through fall, esp. the stunning vernal color, but once the leaves senesce and fall the tree's structural deficiency becomes obvious. 'Katsura' is one of earliest maples to leaf out in spring which is appreciated since I find the branching (its naked look) marginally appealing, even though I spend considerable time trying to correct the normally clustered and comparatively thin branchlets in a manner that disguises my manipulation, the pruning. Moreover, the narrow crotch angle also serves to trap / catch leaves.
(b) to open the specimen, to reduce the plant's shade, both the interior of the canopy where shade induces self-pruning, and on the ground below. This reduction can also promote leaf formation in the interior of the crown.
(c) to shape (i.e., to form, to orient {OOPS, that root again}, to moderate size, to reveal, to keep off and away from, and to cleanup). Upon examination, I commonly find that the canopy of older maples have a high percentage of deadwood. Beside the excuse "I didn't know", I also often hear "I/we don't have the time." Do yourself a favor, learn how and find the time.
When to do the pruning is an important consideration. Moreover, the deadwood of woodies has a distinct color. For maples the deadwood on the smaller diameter branches is grayish -- they are also more susceptible to pressure snapping, leafless, and scratch brown. Maple deadwood, even the bigger branches on specimens that have been ignored for years, frequently can easily be removed by simple finger pressure. One can cut and remove maple deadwood at any time of the year, but DO NOT cut into living tissue from mid winter thru mid summer. Maples are prone to "bleeding". Spring sap flow will be excessive if cut at the wrong time. If you need to do finishing cuts on live tissue -- the snapped dead branch stubs usually need cleanup cutting -- wait until late fall to early winter when the canopy is dormant and the leaves have senesced and no longer obscure. If pruning to shape involving living branches, it is better done as progressive / ongoing attention -- when the plants are smaller and requires foresight. While cutting larger diameter branches is doable, it is not the recommended course. Finally, with respect to timing, there is another aspect of pruning one needs to consider. BEST LIGHT -- direction and/or intensity. Trying to prune without good light is challenging, especially with branches above head height. Less than proper light makes it hard to discern what to cut or where to cut.
Pruning requires concentration and imagination, is fun and easy, and you will want to thank me for the advice. I find pruning relieves stress. Moreover, you will discover that proper pruning also enhances the health and appearance of your specimen(s). But you will rarely find anyone available to or capable of doing the pruning, esp the fine/finish cutting, and if you could it would be costly as there is considerable time spent studying, deciding what to do. Pruning can be challenging, It involves more than tool and technique -- one must know the plants. Everyone is different and there are lots of them. Think of pruning as "tree service" on a much smaller scale. Learn the skillset while saving money, then share the understanding.
A feature of Oriental maples that frequently goes unappreciated is the potential magnificence of the exposed trunk (bole) and branches, especially when leafless -- moreso in some taxa than others and sometimes including color and markings. One of my favs is 'Ryusen' (a dwarf A. palmatum). This lovely is a shrub-sized weeping form cloaked with soft green, trending towards chartreuse leaves that turn brilliant red in autumn. The revealed form pops after a snowfall (see pic). Related, an important factor often overlooked when shopping for Oriental maples is the condition and shape of the bole, esp troublesome large crossing branches. See my Oct rant. The bole on mine (the one pictured) has been enhanced by selective pruning and training. Nearly half the branches have been pruned away, yet only one obvious crop. I was surprised to find the specimen, now six feet tall and with phenomenal bole curvature, at Menard's and at a great price a few year ago. Even box stores occasionally get interesting plants but don't expect the staff to know gardening. I have more to offer on this topic in Chapter 27 (Plant Sources and Lust) of my Rantings book. Lastly, it continues to baffle me why so many people dislike weeping and asymmetric form. Perhaps I will eventually discover a correlation, i.e., beyond their being philistinic and mimetic (monkey see, monkey do, or the reverse). Unfortunately, there are few good gardening examples to emulate in most communities.
I have more to say on maples as a group and about individual species and cultivars in Chapter 90 of my Rantings book and soon will be posting a related rant on native landscape trees, especially maples. I have more pruning advice in Chapter 44.
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PS This was my 78th posting (rant). It would be beneficial to hear what my readers think. I had thousands of unique visitors from 80 different countries during the past year but only two posted comments. Yes, the number of visitors would increase if I used social media platforms like Facebook. There are multiple reasons for why I will not. Mind you, I am not seeking celebrity or pen pals, and I might not respond to comments, but it would be useful to get some feedback. For example, why do you read what I have to say? Are my comments helpful or is it more how I say it (entertainment)? Perhaps there is a topic you would like me to consider. There are > 50 in the hopper, time permitting.