Hi guys!
Allow me to answer this one (I have an orchid business and am really involved in the orchid community...). There is no magic recipe for fertilizers. It all depends on the species/hybrid grown, its age, the time of year, the growth cycle the plant is in, the light levels the plant gets, etc. A rule of thumb would be to use half the recommanded strenght of the label. If it says 1 tbsp per gallon, go half!
ALWAYS wet the medium first, then water with room temperature water with the fertilizer dissolved in it.
Rule of thumb:
For plants in growth mode, use 30-10-10. This will allow the plant to use maximum Nitrogen.
For plants ready to bloom, use 10-30-10 for about 3 to 5 waterings.
For plants with extended blooming periods like phalaenopsis, use a balance fertilizer like 20-20-20.
Note that the numbers don't have to be the same, as long as the ratio stays the same.
There's sooooo much more to talk about here but that's the basic.
Side note: The effectiveness of any fertilizer might be impeded by the dissolved salts in the water. Some micro-elements of the fertilizer might precipitate (go to the bottom of the container) when mixed with "bad water" hence reducing the effectiveness.
If you have more questions, feel free to write back!
Jo