I've tried a few times to grow potted herbs in my apartment with varying success, and I suspect it is related to the potting soil. I have basil and rosemary that are thriving in pots filled with MiracleGro Potting Mix, but I planted chocolate mint, spearmint, ginger mint, thyme, and tarragon in pots with MiracleGro Moisture Control potting mix, and those all died extremely quickly (within a week - one of the mints turned completely brown and shriveled within two days).
I followed the directions from the tags the seedlings came with (regarding sun exposure and watering), and I was careful not to damage the root bundles when I potted them, so the only thing I can guess is that the Moisture Control potting soil did not get along with these plants.
Does anyone know why that is? Is there something about the pH level or nutrient levels in this particular soil that make it ill-suited for herbs? Are there certain things I should look for on the labels when purchasing potting soil in the future? (I live in a city and have a very limited selection of potting soil types and brands in my local hardware stores/target.)