Cattleya sheaths turn yellow

Q: The sheaths which form on the new growths of my cattleyas turn yellow and wither instead of producing flowers. Why?

A: There are two distinct growth types for cattleyas. There are those that produce their new growth in the spring and flower shortly thereafter while the sheath is still green. The other type also produces its new growth in the spring, but does not flower until late fall or early the next spring. In the later case, the sheaths are often dry and papery by the time the plant flowers. Also, sheaths sometimes abort for a number of physiological reason; e.g., not the right night temperature or too much nitrogen applied in the fertilization program.