Ask Mr. Smarty Plants

When you say you "are planting" Quercus fusiformis (plateau oak), please  tell us you are not planting it now, in the August furnace of Texas. Apparently, it is being planted as far north in Texas as Denton County, not just on the Escarpment of Texas, for which it is named. Also, we hope you have not already purchased it and have it sitting in a black plastic pot waiting to be planted. If so, it's roots are probably fried.  Woody plants should be planted in late Fall or Winter in Texas, when they are somewhat dormant.

Much as we love this oak, we want to try and discourage you from planting it in the residential setting you have indicated. In the first place, this tree, although relatively slow-growing, will mature to about 50 ft. in both height and width.  The roots beneath the soil can reach up to two to three times the size of the crown of the tree.  15 ft. is not nearly far enough. Take a look at these pictures from the University of Texas Archive of Central Texas Plants.  Probably these are older than 20 years, but nevertheless, sooner or later, either the tree or the house will have to go, not to mention the house next door. 

Another thing we would like to mention is Oak Wilt, to which Quercus fusiformis (plateau oak) is extremely susceptible. If you look at this  Texas Oak Wilt Partnership site, you will see that Oak Wilt is present in North Texas and is very difficult to deal with.

If, as we said, you have not already committed to the planting of the tree, we would suggest a smaller tree more suited to a residential situation, and not as likely to contract a deadly disease.