Question
My Phalaenopsis orchid began to loose it's leaves pretty much right after I got it.  Now 1 month later they have now all turned yellowish/brown and "floppy" and have fallen off.  The flowers are still blooming and look good.  Looks sort of like too much water and/or not enough sun?  I have heard different views on how much filtered sun and direct sun for these as well.  How often too fertilize too?  I have been fertilizing about once a week (little less) with weak solution.  Thank you in advance for your time!
JoAnne

Answer
JoAnne, let me first address the issue of yellowing and floppy leaves as that is the most critical here.  Your leaf loss is due to root rot.  When roots are rotted, the parts of the plant they serve cannot survive.  Here are the steps I recommend:  First, purchase a bag of orchid potting mix.  Be sure it's specifically for orchids.  Most garden centers such as those at Home Depots or Lowes should have this.  Once you have this home, remopve a portion and soak it.  While it is soaking, remove the plant from its pot and wash most of the old potting mix from the roots.  You will find roots ant are mush or stringy.  Those are dead and need to be removed.  Hopefully, you have some healthy roots remaining.  These are firm.  The root exam will give you an idea of your chances of plant survival.  You need some of the healthy roots to generate new growth.  Leaves that have not fallen but are floppy or yellowish will be lost.

Unfortunately, your plant suffered root rot long before you got it.  This is usually the result of poor potting media which holds water and reduces air flow in the potting mix.  I know that some places (eg Home Depot) will replace your plant if you explain what happen and return the plant.  If the potting mix does not let water and air flow freely through it the result is root rot.  Orchids also need to be repotted every year to keep the roots healthy.  The mass marketing of orchids results in plants being provide to retailers for a quick sale.  The long term condition of the plant is often not considered.  To compound the problem, mass marketers usually do not have staff experienced in orchid plant care, making a bad situation worse.

Watering healthy plants in fresh potting mix should be done weekly and should be fed weakly weekly (about 1/4 tsp per gallon of water.)  Morning sunlight is best.  Indirect or filtered light is also good for phalaenopsis.  Please let me know if I can be of further assistnce