How long does fresh parsley stay good if kept in a refrigerator?
You can also preserve herbs by wrapping them in damp paper towels (either completely or just around the stems) and then placing the bundle in an open plastic bag (or one with holes poked in) Replace or re-wet the towels when they get dry. It's the equivalent of a vase without the worry about it spilling.
If you stand it up in water like a flower, these guys say 7 to 10 days. I say 2 weeks, even.
That link has a freezing technique, but I think thawed parsley is worthless. Dehydrated is okay when you've no option, but it's very bland and too earthy, to me. Where I live, it's cheap, so I just stay stocked up on fresh stuff. Both parts of this advice goes for bundles of cilantro leaves as well.
Here's a variation of Martha F.'s answer: discard any brown leaves, wash the parsley, shake dry to remove as much of the water as possible, wrap in a dry, clean, cloth dish towel, place in a supermarket plastic bag and store in the refrigerator vegetable bin. The parsley will keep for 2-3 weeks. Few people use the stems--although they can be finely chopped and sauteed in olive oil with garlic and onions as a base for sauces--in which case, cut off the stems and use to create a stock. www.menwholiketocook.com
Usually, it can last about three days, or four if you're lucky. This is for normal fridge temperatures (about 4 degrees C), and normal parsley.
If I'm not mistaken, the optimal temperature for leafy greens is about 12 degrees Celsius. That'll get you a few more days.
If you're worried about being able to tell when it's spoiled, it's quite simple. The leaves will become sort of gooey and discoloured. The other option, for different humidity situations, is that the parsley will dry out. Either way, it's obvious that the parsley is no longer fun to eat a lot before it becomes a problem, there's little danger of it passing its use-by date unnoticed, like with meat products.
Parsley can last up to a week, if you keep the leaves dry and weed out any leaves that are starting to turn, and are not put off by the decaying parsley matter. Putting a dry paper towel around the leaves will keep the moisture level down, and cause the parsley to last longer, this also works for lettuce.