Ask Mr. Smarty Plants

If you follow this plant link, Chilopsis linearis (desert willow), you will learn that this tree can grow to be 15 to 30 ft. tall, and  it can be expected to develop into a wider space than 5x5 ft. It needs full sun, good drainage and not a lot of water, and should do well in your part of West Texas. However, it does need room, and is not the sort of tree you would want to prune into a shape, or reduce its natural size. In spite of its name, it is not related to willows. The Desert Willow is valuable in reducing erosion on the side walls of canyons and has beautiful purple, pink and white blooms. We would suggest you find a larger space for your little tree, where it can grow up to be a big graceful tree. 

To replace that tree in your spot by the porch, let us suggest a few smaller shrubs that would probably work out very well there. We will go to Recommended Species, click on the High Plains on the Texas map, and select for shrub under Habit. From this we selected two shrubs, and then picked another one that we especially like and that we think would do well in your part of the state.

Mahonia swaseyi (Texas barberry) - 3 to 4 ft. tall, evergreen, blooms yellow February to April, needs full sun

Mahonia trifoliolata (agarita) - 3 to 6 ft., evergreen, blooms yellow February to Arpil, sun to part shade

Leucophyllum frutescens (Texas barometer bush) - 3 to 6 ft., evergreen, takes pruning well, blooms white, pink, violet, can bloom periodically year round, needs sun to part shade.

Chilopsis linearis

Mahonia swaseyi

Mahonia trifoliolata

Leucophyllum frutescens