I have a beautifly peace lilly. I only water it when it droops. The edges of the leaves are yellowing. There is also some dried brown edges mixed in with the yellow. Why are they like that?

You should water your peace lily when the top inch or so of soil is dry. Allowing our plant to dry out to the point of drooping on a continuous basis is damaging to the plant. Here is a very informative article on peace lily care you may want to read:

Spathiphyllum , Peace Lilies
There are very few plants that really do well in a low light situation and this is the best of them. Spathiphyllums are commonly used in homes, offices and shopping malls because they are so easy to grow and will adapt to a wide variety of conditions. They are also one of the few low light plants to bloom reliably. Spathiphyllums are also called peace lilies, named for the creamy white spathes that look very much like a calla lily. Botanically, a spathe is a bract (modified leaf) enclosing a flower cluster or spadix (fleshy spike). The elegant white spathes on peace lilies are referred to as their flowers.
Spathiphyllums are clump growing tropical plants with many stems emerging from the soil. The different varieties may vary in the size of the leaves and overall size of the plant. A new compact version has become very popular in the past few years. Their foliage is always glossy, green, long and narrow. Different varieties now offer darker greens or narrower leaves and some also bloom more than others.
To select a good, healthy spathiphyllum, look for a plant that fills out the pot. It should have new foliage emerging within the mature leaves. If you are buying the plant for the blooms, be sure to select a specimen that has at least one flower open because they do vary greatly in size and color.

Tips for Growing Healthy Spathiphyllums (Peace Lilies)
What are the light requirements for spathiphyllums?
They are low light tolerant plants. If you can comfortably sit and read in the spot, the plant will do all right. Winter sun is fine, but avoid direct afternoon sun in the summertime.

How much water do they need?
Keep the soil evenly moist all year round. Do not allow it to stand with water in the saucer for more than an hour or two.

Do they have any special temperature requirements?
They are well suited to average indoor temperatures. If they are kept where it is warmer, be sure to keep the soil moist and raise the humidity around the plant.

Do peace lilies need much humidity?
They need high humidity and should be misted daily or kept near a humidifier or on a humidity tray.

How much fertilizer do they require?
During the spring and summer, when the plant is most actively growing, feed them every two weeks with a liquid or water soluble fertilizer such as Excel Gro. In fall and winter, cut back to a half strength solution once a month.

What type of soil do they prefer?
Use a peat-based potting soil such as Bachman's Exceloam.

When should I repot my peace lily?
Repot them each spring. They like to be a bit crowded in the pot and require excellent drainage.

Will they need any grooming?
Give them an occasional shower to remove any accumulated dust from the foliage. Also, as flowers fade, clip off the stem as low as you can reach.

How are they propagated?
Almost all spathiphyllums are now propagated through a laboratory procedure called tissue culture. They can also be divided.

Troubleshooting Problems with Spathiphyllums (Peace Lilies)
Why won't my spathiphyllum bloom?
The most common reason a peace lily doesn't bloom is a combination of too little light and too little humidity.
Sometimes very mature plants don't bloom well. Try increasing light, humidity, fertilizer and dividing if it is severely root bound.

What caused spots on the blooms?
Sprays, especially leafshine or insecticides, will spot the blooms.

If the whole plant looks wilted, what it the problem?
Too much or too little water will cause wilting. So will temperatures that are too cool.

What make the leaves look dull?
When a spath is kept too cool (below 60º), it tends to get a dull look to the foliage. Extended periods of too much cold will lead to problems with stem rot.

What causes brown tips or edges on leaves?
Most brown tips are caused either by low humidity or a build up of salt in the soil from fertilizers and alkaline tap water.

Why do some stems seem too weak?
This can be caused by drought or high temperatures. Spaths can stand higher temperatures if they are kept moist and the humidity is high.

If some of the leaves are yellow, what it the cause?
Yellowing, especially on inner leaves, usually indicates that the plant is being kept too wet. Too much sun might also result in a few yellow leaves, but they will usually be outer leaves.

Are there insect problems with spathiphyllum?
Watch for the occasional outbreak of aphids on the young succulent growth. If the humidity is low and the temps are high, they may have problems with spider mites too.

Are they prone to any disease problems?
Except for root or stem rot from too much water, spathiphyllum rarely have a disease problem.

Saying the plant will tolerate low light means that it won't die if that is the only light source you have. But bright light will increase your chances of blooms. Try raising the humidity for the plant by misting it every other day or so. During the spring and summer, when the plant is most actively growing, feed them every two weeks with a liquid or water soluble fertilizer. In fall and winter, cut back to a half strength solution once a month. Increasing the light and humidity, as well as feeding the plant, should help with the blooms. Hope it works!

If you use hard-water, that can cause the brown/yellow tips. Other causes, dry soil, wet soil and/or over-feeding, light not right. The brown tips are really no big deal if it's from hard-water, it's common, like with spiderplants. You can cut the brown areas a little to make it look nicer if you like.
You can use chemical free rainwater or distilled water which should help.
Keep the soil basically semi moist, not watering everyday, but maybe once a week. Let the top inch or two dry first, then water it throughly.
It's also important to not over-pot, let the plants roots get semi root-bound, over-potting can cause the brown tip problem to worsen. Feed sparingly now and then using only half strength, none in late fall-winter.

I have my Spath drooped since two days. I was worried. I was watering it but it still looks dropped and the stems appear so weak. I took it to the flower shop in our town and they felt it needs more water.(I thought it was over watered) So I added more water until it drained out of the pot. It is still drooped....as though its going to die. The leaves look fresh and green. None of them turned yellow.
Please suggest how to save it. It worries me.

I have a peace lilly that I have had for two years. It was quite cold last winter since I lost my heat for a while. Most of the leaves turned brown and those that still exist are brown about half way down. As the weather warmed up, I decided to resurect it and repotted it in soil from a worm bed. I also separated the roots a bit as is usual for repotting. I have it in a southern window and it seems to be holding its own, but changes are so slow I am scared. I read the other articles and will decrease the water in the saucer and only fill it weekly. Any suggestions?

I read in another article on this plant that they like to be somewhat crowded in the pot, but that you should repot each spring. Going on that I would leave it in the pot you received it in for this year and repot next spring. There is really a wealth of information on this plant on the web just type it into any search engine and browse the articles. I'm finding something new in each article I read!