I have recently planted 5 Lophostemon Confertus aka Tristania Conferta aka Brisbane Box, Vinegar Tree, etc. along the West side of my house. There is a block wall 10' West of my house with the CA required 2' wide and 2' deep reinforced concrete foundation. The 24" box trees were planted very close to the block wall foundation so the trunks of the trees are about 15" from the block wall foundation and about 24" from the wall.

I originally assumed these would give me the shade that I NEED for a few years while my West side shrubs grew up to replace the large ones that were destroyed by the morons that built the wall.

I need to dig a trench 20" East of the trees to run a drain line from the back yard. Since I will dig that trench with a mini excavator, installing a 24" deep root barrier (www.deeproot.com) would not be difficult. This would give me the effect of a 36" x 40' container with no bottom for the trees. My research on citrus trees has show that their size is severely limited when they are grown in containers. Am I crazy to think this would limit the size of these trees?

Here is a picture of one of these trees that has been growing in a local shopping center for 20 years since planting. This is about the maximum size that I would like to see these trees get before the would be a problem.