Fertilizer mainly comes down to 2 questions.
- "What kind of fertilizer should I use?"  
- "How often should I use it?"

"What kind of fertilizer should I use?"
          In general, a good all-purpose "balanced" fertilizer is sufficient for good plant growth.  What does "balanced" mean?  A balanced fertilizer is described as having equal concentrations of N-P-K (nitrogen, phosphorous, and potassium).  This is indicated on the label by the numbers 10-10-10, 14-14-14, or some similar combination.  For improved flowering, you should switch to a blooming fertilizer, high in phosphorous (P) when your orchid plants begin to bud.  (Blooming fertilizer will have a high middle number (P), such as 10-40-10 or a similar combination).  For more information on N-P-K, see the section on below.
          Fertilizer comes in many forms from liquid fertilizer that you have to to dilute to time-released pellets that fertilize when you water.  Liquid fertilizer provides more control in feeding, however, time-released pellets are the easiest.

"How often should I use it?"
          Fertilizing performs best when done in small amounts often.  Because there are so many kinds of fertilizer, it is difficult to recommend how much fertilizer and how often.  It is best to follow the instructions provided with the fertilizer.  Keeping that in mind, a liquid fertilizer generally is given in weak solutions every 2 to 4 weeks.  Time-released pellet fertilizer, the easiest method, is typically 1/2 teaspoon every 3 months.  Be strongly careful that you don't overfertilize.
    If you plan to use blooming fertilizer, you should alternate between balanced and blooming fertilizers based on the flowering cycle.  For example, you should switch between fertilizers every 6 months for orchid plants that bloom 1 time per year.  For plants that bloom twice a year, you should switch every 3 months.  "When do I start counting?"  You should start the balanced (growth) fertilizer after the plant finishes blooming.  Blooming fertilizer should not be used until there is sufficient new growth.