Tree for inside/ outside

You could try a dwarf variety of citrus. Dwarf Mandarins for example are listed at 8′-10′ ultimate height. Or Pomegranate. Dwarf varieties include Legrellei, Nochi Shibori, or Toyosho. 

Depth of planting hole should be as deep as the tree’s nursery container. Sinking the root ball too deep means water pools on top and could drown the plant. Here is a detail from the International Society of Aboriculture about proper tree planting: http://www.isa-arbor.com/education/onlineresources/cad/drawings/Planting/L_tree%20planting_24inch%20to%2036inch%20box_compacted%20soil_K.pdf

Preferably, you tell the concrete contractor to leave a planter hole with no bottom in the foundation slab.To prevent roots from heaving concrete, you put in a root barrier all the way around the sides of the planter space. If you’re nervous, specify something like Deep Root brand root barrier. They have depths of up to 48″ but I don’t think that’s necessary. 24″ down should be fine from top of finish grade, but 36″ could be used if you are nervous. It would be similar to this: http://www.isa-arbor.com/education/onlineresources/cad/drawings/PlantingSoils/L_site%20preparation_rootbarriers_diamond%20wells_I.pdf

And use root watering systems like Rainbird’s RWS root waterers, for example, to encourage roots to grow downwards. Don’t compact the native soil too much underneath the root ball and it should work. 

You can do that too. It is a buildable solution.

However, in terms of labor cost (which is the biggest variable that increases total project cost) the time it would take to excavate down, leveling and fine grading, build out the wooden forms, pour, wait for the thicker concrete to cure, and then remove the forms, would be much greater than simply doing a surface pour like for parking lot planting islands or foundations. 

And then there is the risk that comes from having an enclosed planter. Even above ground planters have some form of drainage. A solid bowl risks the plant drowning if the irrigation fails and runs continuously. And the containment for roots might in the end be too shallow and the plant dies from lack of root growth, aeration, etc. as seen in photos here from uprooted trees: http://www.deeproot.com/blog/blog-entries/how-deep-do-tree-roots-really-grow

To dig down 42″ extra inches would not be too bad for a concrete contractor. To dig down 4 to 6 extra feet would be much more trouble. 

Paul,

Also consider maintenance requirements. While I like the use of stone fruit consider the surrounding concrete and if any dropping fruit will cause any aesthetic issue. At your size constraints you are limited and might be more inline with a large shrubs verse tree. Some of the smaller crapes could work, Dr. Hurd Manzanita, Mexican Redbud (if you can find it), forest pansy red bud, or there are some scrub oaks coming into production at the moment.

Jamie is correct in that the planter will need some sort of drainage. If that is not possible you  will have to have a soil set up similar to a roof top garden and a irrigation system that can be controlled with moisture sensors as not to over water.

While the RWS have there uses they do not encourage roots to go downward contrary to what the manuf. states. In your case something with a gph emitter like a tree ring or point source emitters would be better so you have more control over the water.

That set up should be on its own valve and program as well.

Best regards,

Important issues that I believe have not been mentioned:

If the same tree species is to be used, it must thrive in the outdoor conditions but also indoor conditions: winter heat and dry air, summer AC, light level. If light is coming only from above then there will be leaves only on the perimeter of the canopy.

The type of glazing over the planter will affect the exact light quality and quantity available. It may appear “partial to full sun” but in actuality translate into “dappled shade.” The specifics of the glazing matter. Partial sun outside is far more light than partial sun indoors.

You need a species that is very adaptable as to light and himidity levels if you want the same one indoors and out.

The hole need be no deeper than 3′. There must be free drainage and there should be a clean-out for the drainage.

Consider how maintenance issues such as insect control will be accomplished. A citrus with scale permanently planted in a living room is a hassle. Using strong systemics inside has potential issues as well should that be considered.

How will it be watered?

What soil mix will you use indoors? Repotting a permanenet indoor tree is a real project

Think it through completely

That is Crassula ovata. My family grew it in filtered sunlight right next to the foundation of their house. Direct sun should be fine outdoors. 

The depth of the hole should 36″ to be safe. The plant does get to 6′ tall with age. 

in the 80’s I worked for a huge AE firm that designed many buildings with atrium spaces.

here’s a few tips I learned:

you must acclimate the tree going inside for much less foot candles of light. while the tree growing outside is getting maybe 50,000 foot candles of sunlight, the tree inside may only get 500 foot candles at best with artificial lighting. be sure to use red and blue spectrum lights.

Another big factor is that the tree inside may get no side light. this causes the tree to grow spindly and lean toward the light source…if a skylight is overhead, this will not provide adequate light…please do your research since none of the other issues of installation will matter if the lighting is not properly addressed….