You can pile leaves or mulch over and around the blocks for insulation, and maybe a tarp during the realy cold snaps. Just make sure you don't pile them up on the trunk.

It looks good that way! perhaps a japanese stone lantern ornament on top of the wall.

Awesome...thanks for your feedback!

Only follow up is at what TEMP is a really cold snap...meaning if it is 20 degrees....do I need to worry. Also assume snow is an insulator...so if I have 1 ft of snow and then 0 Degrees I am fine, but no snow and 20 I am not.

Or should I quite having OCD issues and in the winter simply keep a tarp on at all times.

Well, the Tamukeyama is rated down to zone 5, which is -10 to -20. I'd pile up the leaves in fall and throw a tarp over it if temps are to fall below 0 for more than a few hours overnight.

Ok, great thanks!

I knew I said that was all my questions...but as I continue to read and learn....JM roots are shallow and tend to spread out vs. down.

Will my "enclosure" limit the growth or cause any issues ? Or am I just overthinking!

you might want to post this over in the tree forum.. for further discussion ... a tree is a tree ... there should NOT be many rules.. specific to JM ....

ground freeze.. roots getting cold .... are the least of your issues ..

in my world.. winter sun ... winter wind.. and going in and out of dormancy would be the killer options ... as compared to worrying about the roots ... [its those mid winter thaws that wreak havoc with dormant plants]

it appears this thing will be in open prairie.. no wind protection at all... all winter long ... correct???? ... some burlap on posts might be the best idea ... at least for a year or two ...

also.. what do you plan to use to fill the container???

finally.. tell them where you are... z5/6 is more than half the US... it MIGHT matter ...

ken

Oh ok, for some reason I thought JM were just a bit different...

Thanks for the tip on winter sun and wind....figured that would hurt as well....I also thought about burlap and now for sure I will.

The fill will be "Special mix" that I was told is optimal for JM - some peat moss, organic manure, sand and soil.

As for zone, I am in Northeast Ohio, and my exact city seems to be in the middle of 6a, 6b and 5b, so I was confused.

Pay no attention to Ken ;-)) First, he hates maples (what the heck are you doing here anyway, Ken ??) and JM's ARE different, especially in that configuration, which is essentially just a large container....although without a bottom.

Rather than the really unattractive little concrete block jail, why don't you just create a berm or mound of soil and plant the maple on that? Far more natural looking and if sufficiently large, you can select some other plants to keep it company. Even a landscape boulder or two!! Berms immediately afford good drainage, offer the ability to tailor soil specifically for plant needs and add some dimension and contour to a typically flat landscape.

Japanese maple roots are quite sensitive to cold and in that sort of tiny raised bed/container planting, the surrounding air temp can indeed get too cold for safety. Irreparable damage can be done at around 26F, which is not hard to achieve with only concrete and a small amount of soil to insulate the roots. Even in my very mild climate, I need to take precautions for container grown JM's in winter.

Here is a link that might be useful: creating berms

Sorry for the long delay in the response....

Ok..no worries on Ken :-) I do understand JM are different of course.

As for the mound/berm...that was my original course of action, but the soil drains SO SLOW I am just freaked out about it. Meaning if I create a mound, it will be 2 ft above the grade with the entire root ball sitting on the bad soil. But I guess that is the idea, meaning I will need to truck in a few yards of dirt to make the mound large enough.