Question
My peace lilly is leaning to one side and is rather long on the stem and not growing well.  Can this plant be pruned to encourage new growth.  If so when and how should it be done.  In advance thank you for your help.

Answer
Sounds like your Peace Lily needs more light and/or water.  How are you watering this plant?  What kind of light does it get?

Sunlight reduces stem cell Auxins -- Plant Hormones that makes cells grow.  With lots of Auxins, Plants get long-stemmed and leggy.  The leaves become way too heavy to be supported by the long, wishy-washy stems.  You want to STOP those Auxins and get more Sunlight onto those Stems, into those Spathiphyllum leaves, but you DON'T want to give it too much Sun -- which could burn it.

Fertilizing will only make more Auxins.  Without adequate Sunlight, the Spathiphyllum will never be the thick, dense houseplant you really want.

Please correct me if I have this wrong and we'll go over the other options.  My money is on the light/watering detail.  Thanks for writing.