How to Fertilize Dendrobium antennatum?
Half-strength orchid feed every two to three weeks in active growth

Dendrobium antennatum · Dendrobium antennatum
Plants are best grown in a pot in an epiphytic, medium grade, bark-based potting mix with added perlite, moss, or coir. As with many orchids, they grow best when the roots are slightly restricted. Therefore, avoid over-potting or frequent root disturbance. It is a warm-growing orchid and the temperatures should not drop below 16°C. Provide very bright light conditions and 80% humidity throughout the year. See indoor orchid cultivation
Half-strength orchid feed every two to three weeks in active growth