How to Water Dendrobium farmeri?
Keep potting medium lightly moist, airy, and never stagnant

Dendrobium farmeri · Dendrobium farmeri
Plants are best grown in a pot or a basket, 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 cool to warm-growing orchid with average temperatures between 12-25°C. Provide bright light (avoiding direct mid-day sun) and higher humidity by misting regularly in spring and summer, then move the plant to a bright but cooler place in autumn and winter. Reduce watering and feeding until warmer temperatures initiate new growth in spring. See indoor orchid cultivation
Keep potting medium lightly moist, airy, and never stagnant