Carol,
fertilizing is so much easier in Summer when everything is outside. I like Peters fertilizer the best. About once a week I use 20-20-20 and switch to blossom booster like 10-50-10 when I see spikes. I always look for formulations which contain some Magnesium and Calcium, the label on the package usually mentions micronutrients.
Now before I bring my plants inside in the fall, I drench some of the plants which are extremely susceptible to Mealies and Scale, with the Bayers triple treatment which also includes fertilizer.
Feeding inside during the colder season is not as easy, since my greenhouse has glass panels which would be gummed up/dull with salts in no time flat. So in Winter I feed about once a month using a sprayer, fertilize everything and then immediately rinse off the glass panels with a good shot of rain water. A few months ago I have started to add Magnesium Sulfate ( Epsom salt) at 1 teaspoon /gallon to the fertilizer. Plants which are growing in very bright light tend to have a bit of yellowing on the leaves, that should help with that. ( see especially Cattleyas)
I use the amount of everything as indicated on the label, I don't do the weekly weakly routine on my Orchids, that would be too time consuming for me.
