Gladiolus are early to mid summer and if you stagger the planting that helps lengthen the blooming times.
Zinnias will bloom from shortly after they are planted through the first frost without a problem.
Carnations will also bloom from late
spring Blackberry Lilies will bloom through the summer as well.
Here is my list for fall plants, you'll have to check which will do well in your
zone.
Fall Blooming
flowers categorized by bloom colors available
The perennial grass miscanthus requires full sun and regular water.
The following are examples of colorful flowering plants:
Blue
flowers: monkshood, globe thistle, pale-blue flax, bottle gentian
Pink
flowers: Aster novae-angliae 'Alma Potschke' or 'Honeysong Pink', Japanese burnet (Sanguisorba obtusa), Sedum 'Vera Jameson',
roses, Aster, Suprise Lilies
Yellow
flowers: black-eyed Susans, dahlias, perennial sunflowers, ligularia, chrysanthemums, Patrinia scabiosaefolia, goldenrod, marguerite, golden asters
Purple
flowers: Joe-Pye
weed, asters, Russian sage, ground-hugging spiderwort, autumn crocus, Mexican Sage, Aster, Panzies
White
flowers: dahlias, chrysanthemums, sweet autumn clematis, Aster, Suprise Lilies
Warm Color Combinations: Helenium autumnale (red, yellow, orange, combinations)
Red: Pineapple Sage, Suprise Lilies
I hope this helps.