I apologize for this delayed reply to your gardening question and hope it is still helpful to you.
Very strange. It must be something to do with their growing conditions. Things that come to mind include too much shade or overfertilizing. You might try speaking to your local County Extension Office for any possible factors unique to your area that we are not aware of which might cause Lily of the Nile to not bloom well.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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