Yes definitely, I pinch my Helianthus 'Lemon Queen' in June along with other large perennials like Aster and Solidago. This tends to make them shorter and bushier, and does seem to delay bloom time somewhat.

I just got a division of Helianthus maximiliani at plant swap this Spring which is supposed to grow huge and bloom late in the season. I definitely plan to whack it back next year!

Thanks, Terrene. Your new plant sounds like the one I have. It must be 9 feet tall now, and the first bloom is only thinking about opening!

I wanted to add - Helianthus seems to be a favorite of critters - which munch on it, and it grows back - so I would think they are well-adapted to this type of pruning.

There are a lot of species that get huge - do you have a picture? Here is a link on Helianthus maximiliani.

Here is a link that might be useful: Helianthus maximiliani

I have Swamp Sunflower here (Helianthus angustifolius) and it's absolutely necessary to severely prune them early in the year to control their height...this year I cut them back in June and they still grew huge and flopped over. I think it's all the rain we got here in the east this summer...

Anyone have any experience with pruning Western Sunflower(Helianthus occidentalus)? The literature says that these plants only grow to 2.5 to 3.5 feet. Some of mine are now over 6 feet tall. I was trying to keep this section of plants all in the 2 to 4 ft height range and that is one of the reasons I bought this sunflower. Thanks for any replies.