Last year I noticed that my day lillies did not bloom much after the first bloom.
This year I have thinned out and replanted my day lillies and still they have not bloomed after the first bloom.
Does someone know the reason for this?
I live in the Heights area of Houston,Texas and have these plants for approximately 5 years, are they just too tired to reflower?

Not all daylilies flower again after the first bloom, it depends on the cultivar (and the climate). In my climate rebloom is rare although there are some that will do it, but you should have better luck there in Texas with the ones that do typically rebloom. Do you know what kind of daylilies you have?

If you can provide a photo or two, that would be helpful.
How much water do they get? Also, it also depends on how deep they were planted. The crown (the point where foliage and roots join) shouldn't be planted more than 1 inch below the surface of the soil.

Yellow

There are thousands of different daylilies, many of then yellow. Do you have a photograph taken closer? Even then we may not be able to identify it to determine if it is one that is supposed to rebloom but we can try.

That's a nice mass planting...From what I see, they don't look like Stella D' Oro- but but I think that's the only yellow that can be eliminated.

they look like stellas to me

Frillylily, a close-up shot would help. To me, they don't look cupped enough. I don't know if I'm describing that well. Like, these blooms are opened too widely? Don't know if that helped...
I could be wrong : ) Happens often enough

yes the photo is not close enough for sure, I was just thinking the color, my stellas are fairly orange-people describe them as 'yellow' but mine aren't, more of a gold color I think

In my limited experience with re-blooming daylilies, they never produce as many flowers in re-bloom as in the first bloom. Also, the foliage around your daylilies has also grown over the years and may be robbing them of nutrients and water, and casting shade over them.

I once had to move several daylilies that were planted near our beloved hydrangea, because it was ribbing them of sunlight (and probably water as well.) They are flourishing in their new homes.

Frillylily said:yes the photo is not close enough for sure, I was just thinking the color, my stellas are fairly orange-people describe them as 'yellow' but mine aren't, more of a gold color I think

Apparently, Jablonski thought it was gold as well. That's probably why he named it, 'Stella De Oro'.