Question
I have stellas and they are beautiful and bloom. I also have prairie blues and strawberry candy. The foliage is turning yellow and some are not blomming, they get at least 90% sunlight. Do I need to use bone meal, and when do I apply If so.

Answer
Hi Virginia,
Thanx for your question.  Are they getting regular water?  Is the soil draining well and not overly moist or soggy?  Too wet or too dry can cause yellowing of the leaves.  Too much fertilizer can do this also.  I do not recommend putting any fertilizer on at this time, even bone meal.  It could be rust, a fungal disease.  Please look at this website which has pictures and then get back with me if you would please?
thx,
Tom

http://plantclinic.cornell.edu/factsheets/daylily%20rust/daylilyrust.htm