Orchids generally need a special plant fertilizer composition to avoid getting burn marks on the leaves. The plant fertilizer should promote good growth, good budding, rich flowering and for the plant to stay healthy. The nutrition ratio often varies between different producers, here is one example:
3% Nitrogen (N)
1% Phosphorus (P)
4% Potassium (K).
The rest of the fertilizer consists of other macro- and micronutrients, like Calcium, Magnesium and sulfur.
Nitrogen (N) - gives good growth and fresh green leaves Phosphorus (P) - promotes good budding and rich flowering Potassium (K) - helps the plant build strong stems and a strong root system