And your interpretation of my remark is just as subjective. Concrete curbing is unnecessarily limiting in any landscape, as this situation clearly outlines. If one wants to open up to the potential plant choices available, then one surely does not want to be limited by awkward concrete curbing holding one back by artificially defining and unnecessarily restricting the available planting area. Often these concepts are not even considered until it has be pointed out, in much the same way homeowners are inclined to save all plants just because they are already there - the need to retain should be the only justification in maintaining and concrete curbing just doesn't have a justifiable place in the landscape. As to the 'budget' involved in removal of the curbing and/or enlarging the bed, the only cost involved is elbow grease! It is far better to take the time to layout the garden correctly to begin with and prepare the proper planting areas than prematurely spend money on plants that will rapidly outgrow the area or be too large to begin with. That's just money down the drain. That area in the photograph outlined currently with the curbing is simply too small to accommodate much of anything - certainly not a tree, not even most reasonably sized shrubs. Call me blunt or rude or whatever but I see no reason to not to call a spade a spade when it so obviously affects the outcome of the design. Pussyfooting around such glaring obstacles does not benefit anyone, the OP included.

Yes, I have seen the three tree method that some growers use to produce multi trunk ornamental trees. I even planted a paperbark maple tree that had been handled like that. One of the paperbark trunks dominated and the other two died off each at different times. It did not seem to matter what I did to try and save those, they still died while the dominant one thrived as if no stressors of any kind existed for it. Also planting three young trees together is the technique I myself had tried to get a multi trunked River Birch tree. Five years later, one of those trunks thrived and now has a 3 inch wide trunk with beautifull pealing bark, and which has grown to about 10 feet tall. The other two trunks are currently about 4 feet shorter, also with some bark pealing and with only about 1 inch in trunk diameter. This drastic imbalanced look is why I dug the two shorter trunks, and now have them in bare root form. I have seen other reports of people having success at growing a new single main leader by the cutting back nearly to the ground of the damaged main leader. Of course those damaged trees are usually fairly well established. So I do not know why I could not do the same thing with my single trunked birch trees. That is, as long as I do it at the right re-established root development point. Is this truely a bad idea? I do think that my trees are nearly twice as mature than what past growers generally used for clumping out multi trunk birches, but if I do not begin the process to eventually prune out the current one inch wide trunks for these two trees; they too will likely dominate too much over any new sprouts which I might get to pop up out of each of their own root balls. I have also seen what you suggested concerning the trunks of clumps spreading to far; that is on a neighbor's birch that has only two leader trunks, and which is almost 30 years old. Is my only other option to keep them as single trunked trees. Is this delima, also why I have had such a difficult time finding young multi-trunked Heritage birch trees at my local nurseries. Also am I wrong in thinking a three trunked rootball would tend to grow more slowly and end up with less height potential if all three trunks emerging from one rootball grew at a relatively well balanced rate, and no trunk is allowed to remain, which seemes to so drastically dominate over the other two.

Chaste trees, here, are about $13.00 for a 3 gallon plant. Inside of two years they will be fifteen feet high and wide if planted in decently prepared soil. To look their best, they must have afternoon shade, which you'll have on the northeast side of your house (not on the south east). I love them; however, they require alot of ongoing maintenance. They are really a large shrub, so to keep them in tree form they must be pruned several times a season, not difficult, but time, just the same. Also, they are very difficult to get rid of if you change your mind once they are established, sending up suckers forever. That being said, they never have an "off" season, they are highly drought tolerant, are forgiving if you "muff" a pruning job, and when they bloom, they are real show stoppers. I am not familiar with that particular River Birch, but the ones commonly planted in our area, though lovely when small, tend to get rangy looking once they are more than fifteen feet tall or so. They also drop an awful lot of limbs, and appear to be short-lived for trees. If faced with a choice, I'd go with the vitex, but that's just me. Your opinion is what counts. (I would refuse to pay for a fifteen gallon size plant. They grow so fast, that it would be a waste of good money, IMO.)

It will rebark itself for protection right? ==>>> are you asking if its genetically capable of surviving without your interference ... lol .. one would hope so ... e.g. bark of young maples is smooth ... maybe upwards of a decade ... but sooner or later.. and we always have to think in tree time ... the bark matures and changes ... it doesnt necessarily mean anything is wrong ... its not a great link.. but see the differences https://www.google.com/search?q=bark+of+young+maples&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjciu_bzP_NAhXix4MKHe4KBgYQ_AUICCgB&biw=968&bih=745&dpr=0.9 i am still wondering about being planted like a telephone pole.. and wonder how deep the root flare is ... another link ... https://www.google.com/search?q=bark+of+young+maples&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjciu_bzP_NAhXix4MKHe4KBgYQ_AUICCgB&biw=968&bih=745&dpr=0.9#tbm=isch&q=root+flare sooo ... my bottom line ... its not some hundred foot tree hanging over your house.. so no immediate need to do anything proactive.. unless you are interested enough to pull back some of that soil and grass around the trunk and find out about that ... but again .. in tree time.. it may or may not be an issue... within a decade or so ... ken