When I've had that problem, it was because of not enough water. And by that, I mean currently (within a week-10 days or so before bloom), not a year ago.

Are the blooms or scapes smaller?

I was thinking not enough water also but that is only a guess.

The first thing I thought of was heat, but I'm in a hotter zone. Everything shrinks around here during Summer.

I have had some very tiny ones also, and I don't think it is a water problem. Happy Returns and Early Days both had very small flowers compared to previous years. And some others growing nearby have normal size or outsized flowers. Another manifestation of the strange weather?
Christine

When they came out of dormancy this spring, the clumps were smaller, leaves were thinner, and now the scapes are shorter. No blooms open on them yet.

Since they started out that way, that's why I thought it was a result of last year's heat and drought. They went into winter not being the healthiest. Most of my hostas are smaller too because of last year's drought.

However, they're the daylilies I've had the longest, which is what made me wonder if it's because they need to be divided.

Deanna

Deanna - It might be a combination of last year's drought and the clumps needing to be divided. I have some (mostly early evergreens and tender semievergreens with very short scapes this year. I'm not sure is this is an effect of the strange weather or the lack of rain in April.

Debra

Smaller clumps indicates needing dividing? I thought when they get big and crowded the blooms would decline and that means divide?! I have my property edged in day lilies and they are getting so thick I probably need to divide but the task will be so huge I didn't get to it early enough. I have had lilies just disappear on me and it wasn't because they needed division..they just did not survive. I would be inclined to wonder what is eating the root system.

I live in St. Louis and I have several hostas that are way smaller than they were last year. I cant tell about daylillies. I think it is d/t drought last year.