Geraniums get the Chelsea Chop

A few years ago I heard about the Chelsea-Chop: at the time of the Chelsea flower show you chop down to about a third or a quarter certain plants so they don't get too tall and floppy. I have done this with the autumn seddums for the last 2 years and it seems to work. This year, despite all the rain making most things in the garden tall and lush, the seddums are quite short and stocky so I have left them. Instead I have cut down 2 of the 3 outdoor geraniums. The one left uncut is 18 inches to 2 feet high (45-60 cm) and I cut the other two down to about 6 inches high - it looks a bit drastic:

I will compare them and see which does best. On a lovely, warm evening I also sowed corriander, carrots, poppies and flower sprouts.