I second what Brazos says. Houston is simply way too HUGE a sprawling metropolis to not have field target.
The Arlington Sportsmans Club not only draws airgunners from all over the D/FW metroplex, but bordering states as well. I'd think a good airgun club in Houston might draw airgunners from as far away as Sugarland and/or the Woodlands. Of course that assumes there are any airgunners in those outlying areas that are not allergic to Houston (like this airgunner is).
While I realize not every airgunner is as rabid as I am, to illustrate the possibilities I must (reluctantly) use a couple rabid examples.
From the first time I learned about field target competition, I YEARNED for field target competition! When I grew tired of waiting for it, I (and two others) brought field target to Texas by founding the first FT club in Texas. From those beginnings have sprung not only at least FOUR other FT clubs in Texas, but also Texas hosting two FT National Championships, aforementioned rabid Texan bringing Pistol Field Target to the U.S., and creating long-range airgun Bench-Rest Silhouette competition, and, most recently, bringing Extreme Field Target competition to Texas. CORRECTION, bringing TEXtreme Field Target competition to Texas!
So if you want it enough, MAKE it!
Or wait for someone else to do it for you. Good luck with that.