I recently cut or pinched these back for height control:

Leucanthemum x superbum 'Alaska'
Helianthus maximiliani (will do these again later)
Solidago rugosa 'Fireworks'
Echinacea purpurea
Rudbeckia hirta 'Burpeei'

Just about everything for rebloom except late summer early fall bloomers. Usually I just prune out spent flowering stems on most everything until there are very few or no buds left and then cut back by half or more. I stop deadheading/cutting back in early August on anything I plan to get seeds from.

Nepeta musinii (This one just get whacked back to about 4" when flowers are more faded then fresh and before seed set)
Coreopsis lanceolata
Coreopsis tinctoria
Linum lewisii perenne (back to about 8" from ground when flowering slows way down)
Gaillardia
Marigold
Maltese Cross
Ratibida
Rudbeckia
Sweet Alyssum (sheered lightly around top and sides...will continue blooming and clump will double, triple in size after each sheering)
Feverfew 'Flore Pleno'
Knautia
Lavender ( light pruning 2-3" sets of leaves in from base of wands as I harvest all at once)
Dianthus sp.
Thymus sp. (sheered all at once)
Salvia officinalis
Snapdragon
Columbine
Digitalis ambigua
Petunia (pinching out flowers and forming pods)
Nicotiana (cut back to basal leaves)

I'm sure I'm missing something!
Plants I cut back before they bloom to get them bushier:
Helianthus maximilliana
Heliopsis helianthoides
Hollyhock (depending on where they are located). I like the bushier round look with lots more flowers in mixed borders. As they first send out flowering stems I cut all these back down into the foliage.

I think I will try that this year on Aster laevis...last year they were flopping out from weight. Matter of fact I believe I better do that today so I don't set them too far back.

Nothing - - that's why I'm in trouble

Carrie

I just cut down some Asters to keep them from flopping, not for reblooming.

Wait, I forgot:

I cut back my Autumn Joys plants - I replant the cuttings every year. I could have a plant sale and make a fortune just on sedums.

cut back? huh? Nothings even big enough yet!!

:)
zone 5 here....

Coreopsis. Almost all of them will get a trim at some point. Moonbeam and full moon especially.

I've cut back my bee balm, to see if it will rebloom. I want to cut my Mountain bluet, but I want to collect a few seeds first.

I pinch my Joe Pye because it grows taller than I've seen it grow in the wild.
The deer help me with the rest.

Does anyone pinch back cosmos?

Donna Mae

Phlox when 1' tall. Will cut my coreopsis back after blooming also deadhead meadow sage. Thanks for the ideas here. I always deadhead petunias but never cut back. Never thought of cutting my marigolds back, like them the way they are, get better all season.

I've been wondering if it's too late to pinch the Joe Pye Weed. It's Eupatorium maculatum and is as tall as I am already which is 5'8".

Vera, the flowers are all just about spent on Columbine Winky Purple. I should cut all stems to base and leave basal foliage? When you say "then I cut back by half or more" do you mean basal foliage? I got Winky Purple because I wanted that color but true to the warnings they're plagued by leaf miners. The foliage could use general clean up but I remove anything showing leaf miners immediately.

At least the flowers are pretty...LOL.

Hardy hibiscus and lobelia cardinalis.

I don't have to cut back sedums- the stupid rabbits do it for me. This time the little sob left his calling card- a pile of rabbit turds beside the plants.

Karen

... oh karen, I know... but I did read your post way too fast and thought you called that rabbit a "slob"... :0/

Carrie

Carrie: OK, he was a slob too. He left a pile of poop, not socially acceptable.

Karen

"I cut back my Autumn Joys plants - I replant the cuttings every year."

Carrie..any special instructions about rooting Sedum cuttings?

Karen - I am interested in cutting my hardy hibiscus back too. They get almost 6ft tall and I was going to move them out of the beds and to the property edges this spring but I had difficulty digging them and gave up.

How hard do you cut them? half? Third? Just once or more often?

Thanks,
Nancy

I just pinch them back by a few inches, anytime after they're about a foot tall, maybe even a foot and a half. That will cause each stem to divide into two (or is it 4?) and therefore you get way more flowers. Limits the overall height, too.
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Karen

Gorgeous, Karen!

Carrie

donn: About the sedums:

All I have ever done is to pinch off about four or five inches, take off a couple of leaves at the bottom and stick the stems into the dirt. I usually like to place four in a circle and one in the middle, but have also done just one at a time.

carrie

Karen - so just pinching out the center growing tip will reduce the height? OK, I am going to try this tomorrow. Most of mine are about a foot high right now. I want them t0o look like yours - - full and lush!

I hacked my helianthus Max. back by a third this past weekend - clip clip clip with the snippers. This will be a more delicate operation!

I cut back my Althea Rose Hibiscus tree in the spring - cut it down all the way.

For a good bit of time, nothing was growing back and i got scared because I never whacked it down before but it was just way too tall last year.

Now it is a wonderful height and still growing but not out of control... so you see I DID cut back something else this year - - I am SO proud of myself... heh heh -

Tomorrow the Helianthus Angustifolius is getting cut down by half. They get ridiculously tall if they are not cut back in May or June.

Carrie

I forgot about my butterfly bushes and hardy hibiscus. Last year I had a couple of blooms on the Turn of the Century. This year, I chopped it back just as soon as I saw new growth. I have lots of stems this year and hope to have lots of blooms. The Luna Red got the same treatment and is covered in buds.

Turn of the Century.
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