How do you get plants that have flowers to keep their flower blooms?

are they getting sufficient water?

What flowers are you referring to?

Have you tried deadheading the blossoms once they've faded? Flowering plants need to have the spent blooms removed in order to prevent them from going to seed and dying. Pick or cut off the dead blooms on the stem, below the dead flower and above the first healthy leaves.

What I have heard is that you cut off the flower tops when they begin to wilt or dry, so new flowers can bloom.

That is what plants do. Blooms only last for a period of time, then wither. Pinch off the dead flowers to encourage new growth and more blooms!

Dead-head 'em every morning