Why is my houseplant wilting?

Wilting is the result of roots not being able to provide adequate moisture to the leaves and stems.  It can be caused by two completely opposite reasons, either under-watering or over-watering, which can make it difficult to diagnose and solve.  

Under Watering

Check for dry soil conditions.  If the root ball is dry too long or dries out very quickly, roots do not have access to water and plants wilt.   Water more frequently and thoroughly making sure the entire root ball is wetted.  If the container is too small and plants are rootbound, repot in a larger container.

Over Watering

If soil conditions are too wet, especially over an extended period of time, roots begin to rot and die.  With fewer roots, the stems and leaves do not have access to enough water and they wilt.  Always let the soil dry thoroughly between waterings. Check for water on a regular basis and only water when the soil is dry to the touch an inch or two down.  Make sure the container has a drainage hole and that saucers and outer pots and sleeves are not allowed to hold water.  If the soil is old and broken down becoming more compacted, it will hold more water leading to potential rot.  Repot in fresh, well-drained soil.