I've got two cattleyas that haven't flowered in over a year even though they look healthy with lots of new growth. They're on a south-facing windowsill and I feed them monthly. Am I missing something about dormancy or temperature?
Cattleyas need a pretty significant temperature drop to trigger blooming - that's likely your issue. They require a 10-15°F difference between day and night temps, ideally with nights around 55-65°F in fall/winter. If your windowsill stays warm year-round or doesn't get cool enough, they'll just keep producing leaves instead of flowers. Even a south-facing window indoors might not give you that natural temperature fluctuation.
Also check your light situation more carefully. Cattleyas are hungry for bright light - south-facing is good but make sure they're not getting filtered through a screen or sheer curtains. They typically need 3000+ foot-candles. The monthly feeding is fine but honestly that's pretty basic nutrition; consider switching to a bloom-boosting formula higher in phosphorus during fall when you're trying to encourage flowering.
One more thing - if they're actively growing tons of new shoots, they might not be mature enough to bloom yet depending on how old they are. But if they've been established for a while, the temp swing is definitely your biggest culprit. Try giving them a cooler winter rest (around 50-60°F nights) starting in September and reduce watering slightly. Most growers see blooms within a few months of that treatment.
The temp drop thing is real, but also check your light - cattleyas are pretty hungry for bright light and sometimes a sunny windowsill isn't enough intensity-wise. You might also be overfeeding them; too much nitrogen pushes growth over blooms. Try dialing back the fertilizer to every other month or switching to a bloom formula with higher phosphorus, and if you can manipulate temps (like moving them near a cooler window at night during fall/winter), that should help trigger flowering.
both those answers are spot on - the temp drop is crucial but you might also be giving them too much nitrogen fertilizer, which pushes vegetative growth over blooms. try cutting back to every other month or switching to a bloom formula with higher phosphorus, and yeah those night temps really do need to dip into the 50s-60s range to set flower buds.
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