I don't chop back too many things, mostly due to time constraints. I think the one thing I consistently try to chop is my shasta daisies.

I do deadhead a few things though, although again not always consistently. My cosmos I deadhead here and there almost every time I'm in the garden. Zinnias, I cut for bouquets so that's like deadheading. Same with dahlias.

I didn't know phlox would rebloom if cut back - I'll have to try that! Another thing I just heard about two weeks ago (haven't confirmed whether it's true or not yet) is that you can cut back - or deadhead, really, I guess - hibiscus moscheutos and they will rebloom! That would be great if true.

I do cut back some things for height BEFORE bloom though - or at least I try to lol. Mainly asters and monkshood, to keep them from flopping. I have had some asters in my garden for 25 years. I bought them as Purple Dome, but they get to over five feet tall so I think they were mislabeled lol.

:)

Dee

I usually cut back perenniala that grow tall to prevent them from flopping or shading other plants. U have noticed they bloomed later because of it. I spwnd more time deadheading in order to get rebloom. I would deadhead Zinnia, Asclepias tuberosa and Verbena bonariensis. The verbena would probably only grow 1 or 2 new stems. You can experiment with cutting back some Echinacea. You could also grow some of the other Echinacea species native to Missouri. They may bloom at different times compared to Echinacea purpurea. I've just added Echinacea pallida and Echinacea paradoxa to my garden.

Pale Purple Coneflower, Echinacea pallida

Echinacea paradoxa

Echinacea tenneseensis

Echinacea sumulata

Verbena bonariensis

Zinnias respond favorably to getting cut back, but honestly, succession sowing is the easiest approach to keeping them fresh-looking throughout the season. They do well direct sown at 2 or 3 week intervals.

I have read that asclepsia should be cut back right after it blooms, not because it will rebloom, but because monarch cats prefer the fresh tender new growth.

I do get rebloom on phlox with deadheading.

For Echinacea, I agree with Jay. Variety helps. It is also very easy to start a bit from seed each year (I lose some plants ti various fungal yuck every year so new plants refresh the stock and they bloom late the first year. You can often get this same effect through dividing plants in spring.

Another strategy to consider for next year is the Chelsea chop where you cut some plants back by half in May before they bloom. This creates shorter, bushier plants abd pushes the bloom time out a but later. If you have a good sized clump of phlox, you can chop back a portion of it in May and the shorter bushier part will help support the taller stems and bloom later.

Just know that you are not alone. Late summer garden melt down is a common issue and heat, drought, and damaging storms take there toll.