Question
I planted a wide variety  of day lillies about 5 years ago and have divided them several times and they have always bloomed. This year the majority of them have not sprouted flower buds, and I wonder why? They were looking full and healthy earlier in the season, but now the centers of the plants are looking yellow and unhealthy. Some are crowded in among other flowers (such as hollyhocks) but some are not.  I put down Preen near the plants to keep away the weeds every year, but this has not affected their bloom in the past.  I also sprayed Round up on nearby invasive grasses, but again I have done this in the past and it has not affected their blooms.  I watered them during dry spells.  Any answers?

Answer
Hi Carol,
Thanx for your question.  It could be a type of crown rot.  Has it been very wet this year?  Also, the cold spell that most of the country (if you're in the U.S.) received late this year, caused a lot of the flowering plants to reduce blooming (very few of my irises bloomed this year) or caused late blooming.  If you are regularly dividing, that's not the problem.  Are you sure you didn't get a little Roundup on them?  That's all I can think of.  I hope this helps.
Tom