Tom, I never cut them back, unless, of course, you have a shrivelled one.
Some of them will grow to enormous strength and height, and put out prolific
spikes. Others stay compact, but still add wonderful splashes of color.

To keep them growing upright, they need even sun all day. Some people down
here just plant them in the garden and let them go. Keikis are plentiful.

HTH

Diana