Q: I have grown cattleyas for many years. They grow well but do not flower or even make sheaths. I grow under an array of eight 40-watt bulbs year-round. I believe this is enough light. How many hours per day should they be on in spring, summer, autumn and winter? Maybe seasonal day-length variation is my problem. My phalaenopsis flower throughout the year.

A: The amount of light should be approximate outside light – 10 to 12 hours in winter and up to 18 hours in summer. Many cattleyas will not bloom if not given seasonal change. Also, too much fertilizer could affect flower initiation. If you are applying a high nitrogen formula (the first number in the three-number ratio on the fertilizer label) all year, you could be encouraging growth instead of initiation of flower.