Posted: 23/08/2016 at 16:34
Just imagine how tall your cosmos would have been if it wasn't pinched kitty However,,if it has "more of a trunk than a stem" it wasn't pinched back enough or early enough. Pinching would produce several fairly equal stems
it has been a cosmos year though, hasn't it? My white cosmos....pinched several times...is also well over 5' but they is self supporting despite the stiff wind last weekend. If they were not pinched they would have blown over.
not quite pinching but cutting back in May has given me sturdy self supporting and fully flowering sedums now too. .
So pinching and cutting back are ...usually..worth it