grown herbs / cut herbs?

[paolow]

Whenever a recipe I cook needs real 'live' herbs I face a little of a quandry. When I look at the options at XYZ supermarket there are inevitable ingredients for fish (parsley) or curry (coriander) to name a couple of obvious ones that present themselves. I do love the idea of properly fresh herbs and in a supermarket there is usually a vacuum packed version of the above, a powdered version and a living in the pot version. I like the idea of the living plant and usually you get a whole pot of whatever aromatic herb it is for the same price as a prepped and wrapped smaller version of the same thing.
I usually go for the plant alive in a pot and snip away for the voulume of the herb needed to cook the meal happy that come the same problem in the future there will be a ready supply waiting to be harvested.
But, it never works like that! the living herb ALWAYS dies! Whatever I do, in the sun, out of the sun, water, no water, god knows but the herb always gives up in short order. Am I doing something obviously wrong? Am I barking up the wrong tree trying to tap such small source of herbs as an indefinite supply? Should I just buy the vacuum packs? I have toyed with the idea of window boxes (Jamie Oliver has them and they work)(whatever) but is there something I am missing? - other than getting out more?