oops, this is better

These plants look like they have been growing in hardly any light. The browning is a result of too much moisture and/or fertilizer for the given light and temperature. Indoors, they need to be within a few inches of a window with good sunlight or just under a pair of 40 watt fluorescent gro-lights. Here they would like it cool as well, around 70 degrees.

If you have those light conditions, the overwatering and overfertilizing still applies. If you pull the plants out, you will find that the root system has rotted.

If I received plants of any Salvia species that looked as robust as these apparently did when you got them, I'd pot them in potting soil and place outside in a bright, but not direct sun situation. Gradually I would move them to a fairly sunny spot here in PA where it is cooler, or perhaps a few hours of direct sun in TX, where it gets pretty hot. I don't think a humidity tent, wick watering system, or daily spraying of the leaves is necessary. Most salvias tolerate the soil becoming somewhat dry between watering, although constant moisture is probably ideal for many species. Overall, I'd err on the side of too little moisture instead of too much. And as pointed out, bright light is necessary for all salvias.