Approximately 1000 foot candles. Leaves should be glossy medium green, and should increase in size with each new leaf. Prone to moisture problems. Mature plants should not full dry out. Seedlings need more moisture.
Improper humidity can cause bud drop.
Use pebble trays. Do not use fertilizers containing urea on orchids, because urea requires breakdown by soil microbes that aren't generally in orchid media. Toxic salts can build up and damage roots. You should use both inorganic and organic fertilizers, and alternate your brands of inorganic fertilizers regularly to offer your plants the widest possible array of trace nutrients. To prepare your own organic fertilizers, place about 3 handfuls of poultry manure in a 3-5 gallon bucket.