About a month ago I bought cilantro and parsley. I decided to celebrate their beauty by putting them into a vase instead of tossing them in the refrigerator drawer.
So for about five days i got to enjoy the beauty of these babies while I incorporated them into my recipes. The parsley did much better than the cilantro. The cilantro got kind of mucky. I changed the water every day, and still got less than a week out of them. It was so fun to have them "in" the house though!
A few weeks ago I purchased, once again, the necessary fresh cilantro and parsley for my week's worth of meals. This time i threw them in the refrigerator drawer (like usual). They lasted forever, and ever. Not exactly, but they lasted over a week. But I usually forget they are even in there - that's my fault, not pertinent to the experiment.
So just in case you are ever compelled to leave your herbs out in the open in a vase, know that they won't last long. The fridge is your friend, my dears.