Phalaenopsis orchid (or moth orchid) is a beautiful flowering, easy care plant, and blooms annually for a long time. It sounds like you are caring for it well.

An orchid needs to have all its needs met to generate the energy necessary to flower. Adequate light, proper watering, and proper temperature and humidity levels all contribute to a flowering Phalaenopsis. In nature, orchids experience a 10ºF. temperature difference between day and night. This differential is important when trying to initiate flowering, particularly in autumn when several weeks of 55ºF. night temperatures are helpful. After about two weeks of cooler nights, a vigorous plant will initiate a new flower spike that lengthens slowly and buds emerge a few months later. Take care with providing enough light and humidity.

You can read about the correct care routine to give your orchid the strength it needs to flower in our Guide to Phalaenopsis Care.

When were they re-potted? What is the sun exposure? Do you test the moisture level first before watering? Fertilizer weekly, weakly, with the 20-20-20 food at 1/4 to 1/2 the recommended strength, weekly. Maybe every 6 weeks, only use clear water for the week to leach out any built up chemical fertilizer salts. Water early in the day, not at night. Are the plans sturdy in their pots? Usually a wooden stick is secured to the plant with a clip to keep it from moving around. If in the eastern window, which is good, keep right in the windowsill. Southern sunlight is more intense, so the plant may need to be back a bit, and more watering.

Courtesy of NYBG Plant Information Service