Lack of water will do that, so will lack of fertilizer. If the soil is really sandy you need to fertilize more often. I use Milorganite generously around the plants I think the values are 6-2-2 and it's cheap a 30 pound bag is less than $15.00. I noticed the blooms getting smaller here, but it is because it has been dry. I began watering some of the beds each day and the bloom size is going back up so it could be one or both factors. I have been told that the reason all the plants from Florida are so large is because the soil is so sandy they have to fertilize heavily and use fertilizers that are absorbed by the foliage. Thats why when we get them up here they shrink we don't feed them as heavily.

How much milorganite do you use and how often do you use it?
jim

I use a 8oz yogurt container and go all the way around the clump and between the fans. I try to get a thin layer all the way around the plants. I am doing it spring and mid summer. It is weak enough that you really can't over do it.

Darien, bambi too is correct. I live in FL and have very sandy soil. I water every other day and it is not enough for my daylilies. They'd be happier with water every day. I could fertilize every week with Miracle Grow and they'd be happy...but they don't get that. Instead I fertilize every 3-4 months. Also, in my opinion, repeated infections of rust weakens the plants. I throw out the ones that are most heavily infected and keep the ones that show the most resistance. Hope this helps.
Kathy

Amending your soil with compost will help a lot with your sandy soil as well, and therefore helping your plants. And I would agree with the rust as well, but I think if you try to improve the soil, you'll see an improvement in your plants.

Karen

Growing up on Galveston Island where it's nothing but sandy soil, I learned that to have a successful garden I had to add a lot of well-composted manure, leaf mold, and compost. It's a wonderful soil to grow things in, but you do have to add organic material to it.

Nancy