Ask Mr. Smarty Plants

Silverado Sage is a cultivar of Cenizo Leucophyllum frutescens (Cenizo) which is a native Texas plant found mostly in southern Texas counties west of the Brazos River. (see distribution).  The Plant  Profile from the NPIN page says this abut its growing conditions.

Growing Conditions
Water Use: Low
Light Requirement: Sun , Part Shade
Soil Moisture: Dry
Cold Tolerant: yes
Heat Tolerant: yes
Soil Description: Rocky, well-drained soils. Limestone-based, Sandy, Sandy Loam, Medium Loam, Clay Loam, Clay, Caliche type
Conditions Comments: According to legend, Cenizo tends to bloom in conjunction with rainfall. Cenizo is easy to grow so long as it has good drainage. Though this species is the most irrigation-tolerant of the genus, it is susceptible to cotton root rot if soil does not have good drainage and remains moist. Humidity and high night temperatures are lethal. Cenizos should not be fertilized or over-watered. Drought- and heat-tolerant. During very cold winters, may lose a few leaves.

While it is difficult to diagnose plants from written descriptions, you have given a couple helpful clues. First of all, since the plants were planted only a year ago, they could be suffering from transplant shock. I’m including two links to northscaping.com that further explain transplant shock, and offer suggestions for correcting the problem.

Ten Tips for Minimizing Transplant Shock 

First Year Tree and Shrub Care

Secondly, since you are attempting to grow a “desert plant” in the Houston area, overwatering may be the problem. The key is to have well drained soil for the Cenizo to get its roots established.

Two links that might prove helpful:

davesgarden.com A forum discussing Silverado Sage.

greenthumbarticles.com  An article about over-watering